JP7237475B2 - Power modules and switching power supplies - Google Patents

Description

The present invention relates to a power module and a switching power supply for heat dissipation and electromagnetic wave absorption structure.

In switching power supply devices, the speed of switching is increasing along with the development of next-generation devices. Higher switching speeds tend to generate noise, and there is a problem that the operation of power supplies and peripheral devices becomes unstable.

For noise reduction, there is a prior art such as Patent Document 1. In Patent Document 1, noise generated by each circuit of a module IC in which a circuit for analog high-frequency processing and a circuit for digital logic processing are mixed is prevented from affecting other circuits in the module IC. An integrated circuit is disclosed. In this integrated circuit, at least one of a digital logic circuit and an analog high-frequency circuit is sealed with an electromagnetic wave absorbing resin and housed in an integrated package. The electromagnetic wave absorber resin absorbs noise from the electromagnetic wave, thereby reducing the influence of the noise on other circuits in the integrated circuit.

Since communication devices use frequencies in the GHz band, they are likely to generate electromagnetic waves, and are generally provided with electromagnetic wave absorbers. The electromagnetic wave absorber can be arranged in a part of the microwave IC package or directly arranged so as to cover the device.

In Patent Document 2, in a microwave IC package, a microwave signal wiring, a grounding wiring, and a DC bias supply wiring are formed on one surface of an insulating flexible substrate, and the one surface of the insulating flexible substrate is opposite to the other surface. An electromagnetic wave absorbing material is arranged on at least part of the side surface.

Patent Document 3 relates to an inter-element interference electromagnetic wave shield type high frequency module and an electronic device. Of the multiple active element chips mounted, the active element chip that operates in a high frequency band of millimeter waves or higher is sealed with an insulating resin layer in which metal particles that have an electromagnetic wave absorption effect are dispersed in the operating frequency band of the active element chip. ing.

In addition to electromagnetic waves, Patent Document 4 also focuses on temperature, can efficiently absorb electromagnetic waves generated inside, can suppress radiation of unnecessary electromagnetic waves, and the inside is locally high temperature. It is possible to prevent it from becoming hot, and to reduce the rise in the internal temperature. A communication module containing a heat-generating electromagnetic wave source, comprising: an electromagnetic wave absorber that absorbs electromagnetic waves from the electromagnetic wave source; and a sheet-like heat conductor sandwiched between the electromagnetic wave source and the electromagnetic wave absorber, A plurality of bar-shaped heat transfer members penetrating the electromagnetic wave absorber and reaching the heat transfer member are arranged in an array so as to transfer the heat generated by the electromagnetic wave source to the heat conductive base material arranged outside the electromagnetic wave absorber. I have to.

JP-A-2002-134679 JP-A-6-188322 Japanese Patent Application Laid-Open No. 2003-298004 JP 2007-251639 A

However, as in Patent Document 1, the conventional technology is effective for ICs with small power (about several W), but let's apply it as it is to high-speed high-power conversion modules (several kW range modules) equipped with next-generation devices. Even so, it is not possible to suppress large noise caused by high dv/dt, high di/dt, parasitic inductors, etc., which occur in switching of several hundred volts and several hundred amperes (for example, 400 volts and 100 amperes). In addition, the prior art has a problem that it does not have a practical level of resistance required for power modules such as thermal stress cycle tests and high-temperature and high-humidity tests.

Power modules are required to switch high voltage at high speed, and in recent years, with the development of next-generation devices, the switching speed of chopper circuits is increasing. High-speed switching may cause stress when a large surge voltage is applied to the switching element at, for example, the turn-off timing of switching. Sometimes it got out of control.

Next-generation switching elements will use elements such as SiC (silicon carbide) and GaN (gallium nitride) that are capable of high-speed switching at high voltages and large currents. Switching at . Therefore, there is a problem that high-frequency noise due to parasitic capacitance and parasitic inductance of the switching element affects other electronic devices as electromagnetic waves.

As the switching frequency increases, noise due to dv/dt is unavoidable, and a parasitic inductance back electromotive force proportional to di/dt is generated in wiring due to current i, and is radiated as electromagnetic waves. .

Conventionally, electromagnetic waves are shielded by using an electromagnetic wave absorber in communication equipment and arranging it in a part of the microwave IC package, or by directly arranging it so as to cover the element. The signals at are much lower in voltage compared to power switching devices. Furthermore, the electromagnetic waves in communication equipment are noise due to the frequencies used, and the frequencies at which electromagnetic wave countermeasures should be taken are clear.

On the other hand, power modules, etc., which involve high-speed switching operations at high voltage and large current, generate electromagnetic waves due to parasitic inductance and parasitic capacitance rather than the switching frequency corresponding to the frequency used in communication equipment. . For this reason, the corresponding frequency for electromagnetic wave countermeasures is also unclear, and electromagnetic wave absorbers such as electromagnetic wave countermeasures in communication equipment are arranged in a part of the microwave IC package or directly arranged so as to cover the element. Methods alone were not enough. In addition, although countermeasures for elements inside communication equipment are disclosed, nothing is suggested for internal wiring.

The present invention suppresses the generation of noise, generation of electromagnetic waves, and heat generation due to parasitic inductance associated with high voltage and high-speed switching of switching power supplies without being limited by input/output conditions and design conditions, and suppresses generation of electromagnetic waves and low noise.・The purpose is to provide a power module and a switching power supply that enable highly efficient and stable switching operation. A power module is a component that combines a plurality of power semiconductors and integrates power supply-related circuits. Here, power modules that involve switching operations are mainly targeted, and their wiring patterns are included. A switching power supply is a power supply using a power module with switching operation.

In order to suppress the generation of electromagnetic waves in a power module and a switching power supply in which mounted electronic components are packaged, the present invention reduces parasitic inductance and effectively releases heat by means of a wiring pattern that connects elements. It is carried out. Furthermore, the generated electromagnetic waves are absorbed by covering the wiring pattern with an electromagnetic wave absorbing material.

(1) A power module of the present invention is characterized by comprising a switching element and a wiring pattern having a heat radiation portion having a heat radiation wiring width wider than the wiring width of a wiring line.

(2) In the power module of the present invention, it is preferable that the wiring lines and the heat radiation portions are alternately connected.

(3) In the power module of the present invention, it is preferable that the length of the wiring line is not more than twice the width of the wiring line.

(4) In the power module of the present invention, it is preferable that the connecting portion connecting the wiring line has a connecting width equal to or less than the width of the wiring line, and the connecting length of the connecting portion is smaller than the connecting width of the connecting line.

(5) In the power module of the present invention, the width of the wiring pattern may be divided in the direction of current flow.

(6) In the power module of the present invention, the heat dissipation part can be provided so as to protrude into the space between the leads.

(7) In the power module of the present invention, it is preferable that the heat radiation portion between the leads is wider than the length.

(8) In the power module of the present invention, the heat radiation part is preferably covered with an electromagnetic wave absorbing material.

(9) In the power module of the present invention, the electromagnetic wave absorbing material may have a two-layer structure with the insulating resin on the wiring pattern side.

(10) In the power module of the present invention, the electromagnetic wave absorber may be a conductive electromagnetic wave absorber, a dielectric electromagnetic wave absorber, or a magnetic electromagnetic wave absorber.

(11) In the power module of the present invention, the electromagnetic wave absorber may contain an electromagnetic wave deflector that changes propagation of electromagnetic waves.

(12) In the power module of the present invention, the electromagnetic wave absorbing material is preferably an electromagnetic wave absorbing material that absorbs electromagnetic waves having a frequency corresponding to dv/dt or di/dt generated when switching elements are turned on and off.

(13) In the power module of the present invention, when the package of the switching element is connected to the wiring line by wire bonding and there is a parasitic inductance caused by the wire and a parasitic inductance caused by the wiring pattern, the parasitic inductance caused by the wire A wiring pattern is provided at a position where one or more wires to be bonded are the shortest, corresponding to the position of the wire bonding pad of the IC package of the switching element, so that the inductance is minimized, and the wiring pattern is located on the heat dissipation part. is preferably provided.

(14) In the power module of the present invention, the switching elements are preferably semiconductor elements made of gallium nitride, silicon carbide, gallium oxide, or diamond.

(15) A power module of the present invention includes a plurality of power modules in one circuit, and the power module is any one of the power modules described in (1) to (14) above.

(16) A switching power supply according to the present invention is a switching power supply including a power module, and the power module is any one of the power modules described in (1) to (14) above.

(1) According to the power module of the present invention, since it is equipped with a switching element and a wiring pattern having a heat dissipation portion having a heat dissipation wiring width wider than the wiring width of the wiring line, the width of the heat dissipation portion can be widened. As a result, the parasitic inductance can be reduced and the heat dissipation effect can be improved.

(2) According to the power module of the present invention, since the wiring lines and the heat dissipation portions are alternately connected, it is possible to reduce the parasitic inductance and enhance the heat dissipation effect. Since the heat radiating portion is wider than the wiring line, the parasitic inductance is small and the area of the heat radiating portion is widened, so that heat can be effectively dissipated.

(3) In the power module of the present invention, the length of the wiring line is twice or less the width of the wiring line. Here, as the length of the wiring line increases, the parasitic inductance increases, but the parasitic inductance does not increase in proportion to the length, but increases exponentially. Therefore, if the length is the same, the parasitic inductance can be reduced by dividing it in the length direction and connecting it in series. Therefore, in order to reduce the parasitic inductance, it is effective to set the length of the wiring line to twice or less than the width as in the power module of the present invention.

(4) In the power module of the present invention, the connection portion connecting the wiring line has a connection width equal to or less than the width of the wiring line, and the connection length of the connection portion is smaller than the width of the connection line. The parasitic inductance of the wiring pattern of the heat radiating section is smaller when the wiring patterns have the same length and are divided and arranged in series. Therefore, it is possible to reduce the parasitic inductance by limiting the length. can be suppressed.

(5) In the power module of the present invention, the width of the wiring pattern may be divided in the direction of current flow. This is because the parasitic inductance of the wiring pattern can be reduced by dividing the wiring patterns in the length direction in which the current flows and arranging them in parallel if the wiring patterns have the same length and width.

(6) According to the power module of the present invention, since the heat radiating section is provided so as to protrude into the space between the leads, the space between the leads can be effectively used as the heat radiating section.

(7) In the power module of the present invention, the width dimension of the heat radiation portion between the leads is larger than the length dimension. Here, the parasitic inductance of the wiring pattern of the heat dissipation part becomes smaller as the width becomes wider. Therefore, as in the case of the power module of the present invention, the parasitic inductance can be reduced by making the width dimension larger than the length dimension.

(8) In the power module of the present invention, the heat radiation part is covered with the electromagnetic wave absorbing material. By widening the heat dissipation portion, heat generated by the switching element can be easily dissipated, but on the other hand, noise caused by parasitic inductance can be easily radiated to the outside of the power module as electromagnetic waves. Therefore, as in the case of the power module of the present invention, by covering the heat radiation part with an electromagnetic wave absorbing material, electromagnetic waves can be absorbed and radiation to the outside of the power module can be suppressed.

(9) According to the power module of the present invention, the electromagnetic wave absorbing material has a two-layer structure with the insulating resin on the wiring pattern side. A wide selection of electromagnetic wave absorbers is possible.

(10) According to the power module of the present invention, since the electromagnetic wave absorbing material is any one of a conductive electromagnetic wave absorbing material, a dielectric electromagnetic wave absorbing material, and a magnetic electromagnetic wave absorbing material, a wide range of electromagnetic wave absorbing materials can be used. , the material can be selected according to the properties of the electromagnetic wave. A plurality of conductive electromagnetic wave absorbing materials, dielectric electromagnetic wave absorbing materials, and magnetic electromagnetic wave absorbing materials may be combined.

(11) According to the power module of the present invention, since the electromagnetic wave absorbing material includes the electromagnetic wave deflector that changes the propagation of the electromagnetic wave, the electromagnetic wave deflector scatters the electromagnetic wave and improves the absorption efficiency of the electromagnetic wave. can be made

(12) According to the power module of the present invention, since the electromagnetic wave absorbing material is an electromagnetic wave absorbing material that absorbs electromagnetic waves having a frequency corresponding to dv/dt or di/dt generated when the switching element is turned on and off, Electromagnetic waves can be efficiently suppressed by an electromagnetic wave absorber corresponding to generated noise.

(13) According to the power module of the present invention, when the package of the switching element is connected to the wiring line by wire bonding and there is a parasitic inductance caused by the wire and a parasitic inductance caused by the wiring pattern, the parasitic inductance caused by the wire In order to minimize parasitic inductance, a wiring pattern is provided at a position where one or more wires to be bonded are the shortest, corresponding to the position of the wire bonding pad of the IC package of the switching element, and the wiring pattern dissipates heat. Since the portion is provided, the wire on which the parasitic inductance concentrates can be made the shortest, and the parasitic inductance can be suppressed.

(14) According to the power module of the present invention, the switching element is a semiconductor element made of gallium nitride, silicon carbide, gallium oxide, or diamond. can provide a power module that enables

(15) The power module of the present invention may be a power module in which a plurality of power modules according to any one of (1) to (14) are combined in one circuit, and low noise and stable switching are possible. A power module can be provided that enables operation.

(16) A switching power supply of the present invention is a switching power supply equipped with the power module according to any one of the above (1) to (14), thereby enabling stable switching operation with low noise. can provide.

It is a figure explaining the wiring pattern of this invention. It is a figure explaining the approximation formula 20 of the self-inductance of a flat plate. FIG. 10 is a diagram showing the results of calculation of the self-inductance (length) of a flat plate using an approximation formula, where the width is fixed and the length is used as a parameter. It is a figure which shows the result of having calculated the self-inductance (width) of a flat plate from the approximation formula. FIG. 10 is a diagram for explaining an example A of a wiring pattern for reducing parasitic inductance that can be considered from the result of calculating the self-inductance of a flat plate; FIG. 10 is a diagram for explaining another wiring pattern example B for reducing parasitic inductance that can be considered from the result of calculating the self-inductance of the flat plate; It is a figure explaining the approximation formula 40 of the self-inductance of a cylinder. FIG. 4 is a diagram showing the result of calculating the self-inductance of a cylinder from an approximation formula, in which the diameter is fixed and the length is used as a parameter. FIG. 10 is a diagram showing the result of calculating the self-inductance of a cylinder from an approximation formula, where the length is fixed and the radius is used as a parameter. This is the basic circuit of a synchronous rectification step-down DC/DC converter. This is an equivalent circuit considering synchronous rectification step-down DC/DC converter parasitic inductance and parasitic capacitance. FIG. 4 is a perspective view illustrating a power module in which a wiring portion including switching elements is covered with an electromagnetic wave absorbing material; FIG. 4 is a diagram illustrating a schematic cross-sectional view A of a power module in which a wiring portion including switching elements is covered with an insulating material and an electromagnetic wave absorbing material; It is a figure explaining typical sectional drawing B of a power module. It is a figure explaining the electromagnetic wave absorber containing an electromagnetic wave deflection body. FIG. 4 is a plan view of a cascode element used in Examples; FIG. 4 is a diagram explaining an equivalent circuit of a cascode element; Fig. 13 shows a power module equivalent circuit 138 for implementing the present invention; It is a figure explaining the example of the typical wiring pattern for power modules. It is a figure explaining the power module example A which concerns on an Example. FIG. 10 is a diagram illustrating a power module example B according to another embodiment; FIG. 10 is a diagram for explaining the concept of Kelvin connection of power module example B; FIG. 10 is a diagram for explaining a power module example C; This is an application example of a power module to a step-down DC/DC converter. This is an application example of a power module to a step-up DC/DC converter. 164 shows an application example 164 of the power module of the present invention to a three-phase inverter.

An embodiment of the present invention will be described below with reference to the drawings. In addition, in each of the following embodiments, portions that are the same or equivalent to each other will be described with the same reference numerals.

In recent power modules and switching power supplies, the switching elements have become higher voltage and higher frequency, and the reduction of parasitic inductance in wiring has become even more necessary than before. In addition, heat dissipation from wiring patterns has also been required. Switching elements include semiconductor elements made of gallium nitride, silicon carbide, gallium oxide, or diamond, etc. Higher voltages and higher frequencies of switching elements pose a serious problem of electromagnetic wave noise. The main object of the present invention is to solve these problems by reducing parasitic inductance and heat radiation with wiring patterns, and suppressing electromagnetic waves generated by noise with an electromagnetic wave absorbing material for wiring patterns.

First, a wiring pattern for reducing parasitic inductance and heat radiation will be described.

FIG. 1 is a diagram for explaining the wiring pattern of the present invention. The wiring pattern 10 is a conductor that electrically connects the element A 16 and the element B 18, and is composed of a wiring line 12 and a heat radiating portion 14. As shown in FIG. A conventional wiring pattern has only the wiring line 12, but in the present invention, a heat radiation portion 14 wider than the wiring line 12 is provided. By widening the width of the heat radiating portion 14, the area is widened and the heat is easily radiated.

The width _Wh of the heat radiating portion 14 is wider than the width _Wp of the line to widen the heat radiating area and reduce the parasitic inductance at the same time. The length _Lp of the wiring line is limited within a certain range with respect to the width _Wp of the wiring line. The length L _h of the heat radiating portion is also limited within a certain range with respect to the width W _h of the heat radiating portion 14 , and the length L _h of the heat radiating portion may be narrower than the width W _h of the heat radiating portion 14 . Therefore, it is preferable that the wiring lines 12 and the heat radiating portions 14 are alternately connected in series. If the distance between the element A 16 and the element B 18 is short, the number of heat radiating parts 14 may be one.

The self-inductance of the wiring line 12 and the heat dissipation portion 14, which are parasitic inductances, can be calculated from an approximation formula, and the shape of the wiring pattern 10 can be theoretically considered based on the calculation results. The self-inductance of the wiring line 12 and the heat radiating portion 14 can be obtained from an approximation formula as the self-inductance of a flat plate, and will be described below.

FIG. 2 is a diagram for explaining the approximation formula 20 of the self-inductance of a flat plate. Assuming that the flat plate has a shape of height H, width W, and length L, the self-inductance Ln can be calculated by the approximation formula shown in FIG. From the approximation formula, it can be seen that the self-inductance Ln is determined only by the shape of the height H, width W, and length L without being affected by the material because it is premised on conductivity. In the wiring pattern 10, the thickness, that is, the height is about several tens of μm to 100 μm, which is sufficiently small compared to the width and can be ignored. calculated the degree. Although this approximation formula can be applied to the wiring pattern 12 and the heat dissipation portion 14, the wiring pattern 10 will be described below as an example.

FIG. 3 is a diagram showing the result of calculating the self-inductance Ln of a flat plate from an approximation formula. It is the self-inductance (length) 22 of the flat plate whose width is fixed and whose length is a parameter. The width W is 1 mm, and the change in self-inductance (length) 22 of the flat plate is calculated when the length L is from 1 mm to 10 mm. The dashed line indicates the self-inductance when the self-inductance when the length is 1 mm is assumed to be proportional to the length.

The self-inductance Ln when the length is 1 mm is 0.14 nH, and when the length is doubled to 2 mm, it is 0.51 nH. Furthermore, when the length is 6 mm, it is 2.77 nH. The longer the length, the greater the self-inductance.

From this calculation result, for example, if the distance between elements is 2 mm, the self-inductance Ln of the wiring line 12 connecting the distance of 2 mm with a width of 1 mm is 0.51 nH. On the other hand, if two wiring lines 12 with a length of 1 mm are arranged in series, the self-inductance Ln is 0.28 nH, which means that the self-inductance is about 55%.

Similarly, if the distance between elements is 6 mm, the wiring line 12 connecting a distance of 6 mm with a width of 1 mm has a self-inductance Ln of 2.77 nH. If they are arranged side by side, the self-inductance Ln is 0.84 nH. Even if three wiring lines 12 with a length of 2 mm are arranged in series, the self-inductance Ln is 1.53 nH, which is about 55% of the case where the wiring lines 12 are simply connected.

From this result, it can be seen that the self-inductance Ln of the wiring line 12 becomes smaller when the wiring line 12 is divided into a plurality of parts and connected in series. If the width of the wiring line 12 is not more than twice the width, the self-inductance is preferably halved, but at least the division can reduce the self-inductance.

FIG. 4 is a diagram showing the result of calculating the self-inductance of a flat plate from an approximation formula. The self-inductance (width) 24 of the flat plate calculated by the effect of the width W of the flat plate with the length L fixed and the width W as a parameter, and the self-inductance Ln in the width range from 0.1 mm to 4.5 mm is the calculation result of For example, the self-inductance is 2.8 nH when the width is 1 mm, 2.18 nH when the width is 2 mm, and 1.82 nH when the width is 3 mm. As for the width, for example, in order to halve the self-inductance Ln at a width of 1 mm, the width must be increased about five times.

The idea of division can be introduced also for the width. For example, assuming that the width is 2 mm and two wiring lines 12 with a width of 1 mm are arranged in parallel, the self-inductance Ln is 1.4 mH. The wiring line 12 with a width of 2 mm has a self-inductance Ln of 2.18 nH, which is about 64%. Therefore, the self-inductance Ln can be reduced by dividing the width and arranging them in parallel.

In the above, the calculation results of the self-inductance of the flat plate were considered. Self-inductance is a parasitic inductance for the circuit. Expandable.

FIG. 5 is a diagram for explaining an example A26 of a wiring pattern for reducing parasitic inductance that can be considered from the result of calculating self-inductance of a flat plate. In FIG. 5A, the width of the wiring line 12 is extremely shortened with respect to the basic wiring pattern 10 shown in FIG. For example. The connection portion connecting the wiring line has a connection width equal to or less than the width of the wiring line, and the connection length of the connection portion is smaller than the width of the connection line. FIG. 5B shows an example in which a notch portion 30 formed by cutting the connection portion 28 of FIG. In both cases, the wiring pattern 10 is basically connected in series by division.

FIG. 5C is an example in which the wiring pattern 10 of FIG. FIG. 5D shows an example in which the wiring pattern 10 of FIG. The width of the wiring pattern is divided in parallel with the direction of current flow. The separation slit 32 is sufficiently thin and has a width that minimizes the effect on heat dissipation. In both cases, the wiring pattern 10 is basically divided and connected in parallel.

FIG. 6 is a diagram for explaining another wiring pattern example B for reducing the parasitic inductance that can be considered from the result of calculating the self-inductance of the flat plate. Since the power module is equipped with various electronic components including switching elements and requires leads, it does not mean that there is a free space in the wiring area for arranging the wiring pattern. Under such restrictions, as shown in FIG. 6A, there is a case where the heat dissipation portion 14 is provided so as to extend only in one direction of the wiring line 12 . Also, as shown in FIG. 6B, the connecting portion 28 may be biased to one side.

As shown in FIGS. 1, 5 and 6, it is important that the wiring pattern 10 has the smallest parasitic inductance and a high heat dissipation effect within the constraints of the wiring area in the power module.

A switching element mounted on the power module is integrated and may be connected to the wiring pattern 10 by wire connection from a pad for wire bonding. In this case, a parasitic inductance occurs in the wire. The wire is cylindrical and can be calculated from the approximation of cylindrical self-inductance.

FIG. 7 is a diagram for explaining an approximation formula 40 for obtaining the self-inductance of a cylinder. Assuming that the cylinder has a shape of radius R and length L, the self-inductance Ln can be calculated by the approximation formula shown in FIG. From the approximation formula, it can be seen that the self-inductance Ln is determined only by the shape of the radius R and the length L without being affected by the material because it is premised on conductivity. The wire diameter for wire bonding is about several tens of μm to 100 μm. Self-inductance Ln was calculated for the length L and radius R.

FIG. 8 is a diagram showing the result of calculating the self-inductance of a cylinder from an approximation formula, in which the diameter is fixed and the length is used as a parameter. The relationship between the self-inductance (length) 42 of the cylinder and the length L is shown when the radius R is 15 μm (diameter 30 μm). In the case of a cylinder, when the length is 2 mm or more, the self-inductance increases almost linearly. At a length of 2 mm the self-inductance Ln is 1.93 nH and at 4 mm the self-inductance Ln is 4.42 H.

FIG. 9 is a diagram showing the result of calculating the self-inductance of a cylinder from an approximation formula, in which the length is fixed and the radius is used as a parameter. The self-inductance (diameter) 44 of the cylinder is obtained by calculating the relationship between the self-inductance 44 of the cylinder and the radius R with the length L fixed at 3 mm. When the radius R is 15 μm (diameter 30 μm), the self-inductance Ln is 3.14 nH. Even if the radius R is 30 μm (diameter 60 μm), the self-inductance Ln is 2.73 nH.

From this result, it can be seen that shortening the length of the wire is effective for reducing the parasitic inductance because the wire is difficult to split. Also, it is clear that connecting multiple wires in parallel is more effective than increasing the diameter. Therefore, when wire connection is required, it is necessary to arrange the wiring pattern 10 at a position closest to the wire bonding pad so that the length of the wire is short.

The means for reducing the parasitic inductance caused by the wiring pattern 10 has been described above. Next, the relationship between the parasitic inductance and the cause of noise generation will be described using a specific step-down DC/DC converter.

FIG. 10 is a diagram showing a basic circuit 50 of a synchronous rectification step-down DC/DC converter. An input capacitor 54 is connected in parallel with the input voltage 52 . In the step-down DC/DC converter, the average value of the input current decreases according to the transformation ratio, but the same current as the output current instantaneously flows, which is averaged by the input capacitor 54 . The input voltage 52 is connected to the chopper circuit, and the first switching element 62 and the second switching element 64 are alternately turned on/off by pulse signals from the controller. As a result, the output waveform at the intermediate point between the first switching element 62 and the second switching element 64 becomes a pulse waveform corresponding to the switching frequency. An output waveform at an intermediate point between the first switching element 62 and the second switching element 64 forms a smoothing circuit together with the output capacitor 60, becomes a DC voltage through the output inductor 58 connected in series, and is supplied to the load resistor 66. .

Noise in a step-down DC/DC converter is mainly generated by the parasitic inductance of wiring and the parasitic capacitance of switching elements, and will be explained using an equivalent circuit.

FIG. 11 is a diagram showing an equivalent circuit 68 considering parasitic inductance and parasitic capacitance. The switching elements are power MOSFETs, the first switching element 62 is a high side power MOSFET 80 and the second switching element 64 is a low side power MOSFET 82 .

Parasitic elements in the input capacitor 54 are a parasitic inductance 70-1 and an ESR (Equivalent Serial Resistance). ESR also exists in the wiring, and is collectively designated as ESR72-1 in FIG. In the power MOSFET, the body diode and the parasitic capacitance were taken as parasitic elements without considering the Miller capacitance and the gate capacitance. In the high-side power MOSFET 80, the body diode 76-1 and the parasitic capacitance 74-1 are shown in the equivalent circuit, and in the low-side power MOSFET 82, the body diode 76-2 and the parasitic capacitance 74-2 are shown as parasitic elements.

A parasitic capacitance between windings of the inductor and a parasitic capacitance of the substrate pattern occur in the output inductor 58 , which are shown as stray capacitance 75 . In the output capacitor 60, like the input capacitor 54, the parasitic inductance 70-5 and the ESR 72-2 are parasitic elements. Parasitic inductances also occur in wiring, layout, vias, etc., and are indicated by wiring parasitic inductances 70-2, 70-3, and 70-4 in FIG.

The on/off of high-side power MOSFET 80 and low-side power MOSFET 82 is controlled by switching waveform 78 of controller 56, but high-frequency noise is mainly generated when high-side power MOSFET 80 and low-side power MOSFET 82 are turned off. When high-side power MOSFET 80 is turned on, current flows from input voltage 52 through high-side power MOSFET 80 and into low-side power MOSFET 82 so as to cancel the return current of low-side power MOSFET 82 .

Even if the current of the low-side power MOSFET 82 becomes zero, the recovery function of the body diode 76-2 of the low-side power MOSFET 82 reverses the current from the cathode to the anode of the body diode 76-2 until the accumulated carriers disappear. current flows. This recovery current is the short-circuit current i that flows through the input-side loop (see the broken line in FIG. 11) composed of the input capacitor 54, the high-side power MOSFET 80, and the low-side power MOSFET 82, and energy is supplied to all parasitic capacitances present in the loop. is accumulated.

This energy is released at the moment the recovery stops working, and at this time resonance occurs in the parasitic inductance and parasitic capacitance in the loop, resulting in ringing and high-frequency noise. At this time, since the high-side power MOSFET 80 is conducting in the ON state, the parasitic capacitance 74-1 of the high-side power MOSFET ₈₀ is irrelevant _. is the resonance frequency f _r of , and is expressed by f _r =1/2π(L _p ·C _p ) ^1/2 .

The noise of several hundred MHz when the high-side power MOSFET 80 and low-side power MOSFET 82 are turned off circulates in the high-frequency ringing loop of the input capacitor 54, high-side power MOSFET 80 and low-side power MOSFET 82 as a high di/dt current surge. As a result, a spike voltage dependent on di/dt is generated in the input capacitor 54, and a ringing voltage of dv/dt corresponding to the voltage v is generated in the high-side power MOSFET 80 and the low-side power MOSFET 82. FIG.

Since a ringing voltage of _Lp ·di/ _dt is generated at the parasitic inductance Lp, the ringing voltage increases as the parasitic inductance _Lp increases.

A high-frequency ringing current i flowing through the loop generates a magnetic flux that depends on the area of the loop, and this magnetic flux is radiated outward, causing electromagnetic induction in the strip line and loop of the board of the device as electromagnetic waves. Therefore, in a module such as a switching power supply, electromagnetic waves are generated by parasitic inductance due to the ringing current i not only in the noise source but also in the wiring pattern.

The high-side power MOSFET 80 and the low-side power MOSFET 82, which are sources of noise, also generate considerable heat due to switching. Therefore, it is effective to cover the high-side power MOSFET 80 and the low-side power MOSFET 82, which are switching elements, with a heat dissipating material to dissipate the heat. Furthermore, from the thermal aspect, it is also necessary to dissipate heat through the wiring pattern, and in the present invention, the wiring pattern is provided with a heat dissipating portion. Since the heat radiating part has a large area, it has a side surface that makes it easy to generate electromagnetic waves, and it is desirable to cover the wiring pattern with an electromagnetic wave absorbing material. Further, the electromagnetic wave absorbing material is preferably an electromagnetic wave absorbing material that absorbs electromagnetic waves having a frequency corresponding to dv/dt or di/dt generated when the switching element is turned on and off.

FIG. 12 is a perspective view illustrating a power module in which a wiring portion including switching elements is covered with an electromagnetic wave absorbing material. First, as shown in FIG. 12A, the switching elements are covered with an insulating heat dissipating material 110 for the wiring portion 106 in which a plurality of switching elements and wiring patterns are arranged on the module substrate 94, and then As shown in (B), the switching element and the wiring portion 106 are covered with the electromagnetic wave absorbing material 112 . The wiring portion 106 is connected to a lead 92 serving as an external terminal.

FIG. 13 is a diagram illustrating a schematic cross-sectional view A100 of a power module in which the wiring portion 106 including the switching elements of FIG. The switching element 104 provided on the module substrate 94 is electrically connected to the wiring portion 106 by the wire 108 . A wiring pattern having a heat dissipation portion is arranged in the wiring portion 106 . Since the switching element 104 is a source of electromagnetic waves and heat, it is covered with a heat radiation material 110 and an electromagnetic wave absorption material 112 . A plurality of wiring patterns are arranged in the wiring section 106, and the heat radiation section is covered with an electromagnetic wave absorbing material 112 in order to absorb electromagnetic waves radiated from the wiring patterns. The entire wiring pattern including wiring lines may be covered with the electromagnetic wave absorbing material 112 .

FIG. 14 is a diagram illustrating a schematic cross-sectional view B114 of the power module. In FIG. 14, the wiring part 106 is covered with the insulating material 116, and then the electromagnetic wave absorbing material 112 is overlaid on the wiring part 106 as compared with FIG. The electromagnetic wave absorbing material 112 has a two-layer structure with an insulating resin. Since the heat radiating material 110 is insulating, the heat radiating material 110 and the insulating material 116 may be integrally covered up to the wiring part 106 . The heat dissipation material 110 is preferably a highly heat-resistant and heat-dissipating material, which contributes to improved resistance to high-temperature, high-humidity tests and thermal stress cycle tests.

Highly heat-resistant and highly heat-dissipating materials, such as phosphorus-containing epoxy resins containing inorganic fillers, can be used. A coefficient of linear expansion can be obtained. Furthermore, there is a thermosetting resin containing an inorganic filler and having an imide skeleton and an allyl group as functional groups in the molecule. In addition, there is a thermosetting nanocomposite resin that applies nanohybrid technology. This resin has an optimized chemical structure of organic molecules and inorganic nanocomponents, and has a high glass transition temperature due to the chemical interaction between both components, and has excellent heat resistance. By promoting independent cross-linking reactions by both components during curing, it is possible to suppress the deterioration of various properties even when exposed to severe heat history for a long period of time.

By covering the wiring portion 106 with an insulating heat dissipation material 110 or an insulating material 116, the electromagnetic wave absorbing material 112 can be selected from a conductive electromagnetic wave absorbing material 112, and various materials can be used.

The electromagnetic wave absorbing material 112 absorbs electromagnetic waves by converting energy carried by electromagnetic waves propagating in free space or lossless medium, which is electromagnetic wave energy, into heat energy. There are various types of electromagnetic wave absorbing materials 112, but they can be roughly classified into conductive electromagnetic wave absorbing materials, dielectric electromagnetic wave absorbing materials, and magnetic electromagnetic wave absorbing materials. The electromagnetic wave absorber is either a conductive electromagnetic wave absorber, a dielectric electromagnetic wave absorber, or a magnetic electromagnetic wave absorber.

A conductive electromagnetic wave absorber absorbs electromagnetic waves only by its heat generating mechanism. When an electric field is applied to the conductive wave absorbing material, an internal current flows, and this internal current is converted into heat energy. The conductive radio wave absorbing material is formed of a resistor, a resistance wire, or a resistance film, and is preferably a carbon material, or a metal material such as aluminum, copper, nickel, or stainless steel. Use in the form of

A dielectric radio wave absorber is a radio wave absorber that utilizes the dielectric loss of a substance. Dielectric electromagnetic wave absorbers include carbon rubber, carbon-containing polyurethane foam, carbon-containing polystyrene foam, and the like. By forming these dielectric electromagnetic wave absorbing materials into a multi-layered structure, the attenuation of electromagnetic waves near the surface can be reduced, and the attenuation can be increased as the electromagnetic waves propagate inside, thereby obtaining broadband characteristics.

Magnetic wave absorbers absorb energy through magnetic loss. Conductive electromagnetic wave absorbers and dielectric electromagnetic wave absorbers absorb electromagnetic waves when currents flow due to electric fields, but electromagnetic wave absorbers absorb electromagnetic waves due to magnetic fields. Magnetization progresses due to domain wall motion according to the frequency of alternating current magnetization, and as the frequency increases, the domain wall motion cannot follow changes in the magnetic field and domain wall resonance occurs. At gigahertz or higher, magnetization progresses due to rotational magnetization, but at higher frequencies there is a delay. Rotational magnetization is a phenomenon of precession around the axis of easy magnetization under a magnetic field.

Magnetic wave absorbers include sintered ferrite, soft magnetic metals, iron carbonyl, and the like. Ferrite includes spinel type ferrite, planar type ferrite, soft magnetic metal particle composite, magnet plumbite type ferrite, and the like.

The electromagnetic wave absorbing material 112 may be a composite material of conductive electromagnetic wave absorbing material, dielectric electromagnetic wave absorbing material, and magnetic electromagnetic wave absorbing material. Some of these electromagnetic wave absorbing materials 112 are mixed with an insulating resin in order to prevent short circuits and improve adhesion. Further, an electromagnetic wave deflector may be included in order to change the propagation of electromagnetic waves entering the electromagnetic wave absorbing material 112 and absorb more electromagnetic waves.

FIG. 15 is a diagram illustrating an electromagnetic wave absorber 120 containing an electromagnetic wave deflector. The electromagnetic wave absorber 112 includes an electromagnetic wave deflector 124 that alters the propagation of electromagnetic waves. When an electromagnetic wave 122 indicated by an arrow enters the electromagnetic wave absorber 112, it hits the electromagnetic wave deflector 124 and is polarized. Therefore, the propagation path of the electromagnetic wave 122 changes and the electromagnetic wave 122 scatters. The scattered electromagnetic waves 122 are confined in the electromagnetic wave absorbing material 112 due to mutual interference of scattered waves and perfect reflection, and the emission from the electromagnetic wave absorbing material 112 is reduced. Thereby, an electromagnetic wave absorbing function is exhibited. The electromagnetic wave deflector 124 can be mixed with any material and used as the electromagnetic wave absorber 112 . For example, even an acrylic resin that has almost no electromagnetic wave absorption characteristics can be used as the electromagnetic wave absorber 112 if air bubbles are present as the electromagnetic wave deflector 124 . Of course, air bubbles may exist in the electromagnetic wave deflector 124 in the conventional conductive electromagnetic wave absorbing material, dielectric electromagnetic wave absorbing material, and magnetic electromagnetic wave absorbing material.

<Example>
DESCRIPTION OF THE PREFERRED EMBODIMENTS A power module and a switching power supply device according to the present invention will be described below based on embodiments shown in the drawings. The power module is a power module of a switching element (chopper circuit) in which cascode-connected switching elements are connected in series. Each drawing is a schematic diagram and does not necessarily strictly reflect actual dimensions.

FIG. 16 is a plan view of the cascode element 130 used in the example. The cascode element 130 is composed of a set of two chips, and has a structure in which a GaN-HEMT 132 and a Si-MOSFET 134 are stacked. The Si-MOSFET 134 is a vertical device having a drain electrode on the back surface. It is connected. On the surface of the cascode element 130, the drain electrode D1 of the GaN-HEMT 132 and the gate electrode G2 and source electrode S2 of the Si-MOSFET 134 are arranged at the positions shown in FIG.

FIG. 17 is a diagram illustrating an equivalent circuit 136 of the cascode elements. The cascode connection is a circuit configuration in which a normally-on switching element is connected to a normally-off switching element so that it can be used as a normally-off switching element. As a normally-on type switching element, there is a GaN-HEMT made of GaN (gallium nitride). GaN has a bandgap of 3.4 eV, which is larger than 1.1 eV of silicon. Therefore, operation at high voltage is possible.

A GaN-HEMT is a field effect transistor whose channel is a high-mobility two-dimensional electron gas induced by a semiconductor heterojunction using gallium nitride. This GaN-HEMT is normally a normally-on type (depletion mode) that turns on when no voltage is applied to the gate. Therefore, in order to switch the depletion mode GaN-HEMT, a cascode connection is made by combining enhancement mode FETs so as to work as an enhancement mode. Enhancement-mode FETs capable of high-speed operation include IGBTs and the like in addition to Si-MOSFETs.

FIG. 18 is a power module equivalent circuit 138 for implementing the present invention. A cascode element 130-1 is connected in series as a high side switching element, and a cascode element 130-2 is connected in series as a low side switching element.

The gate resistors 140-1 and 140-2 limit the gate charge of the Si-MOSFET 134-1 of the high side switching element and the Si-MOSFET 134-2 of the low side switching element, moderate the rise and fall of the switching waveform, Reduces noise both on and off. The noise elimination capacitor 142 is a snubber capacitor for eliminating noise of the high side switching element and the low side switching element.

The drain electrode DH1 of the GaN-HEMT 132-1 of the cascode element 130-1 used as the high-side switching element is connected to the wiring pattern by wire bonding, and is connected to the lead that becomes the terminal T4 via the connection to the noise elimination capacitor 142. . The gate electrode GH1 of the GaN-HEMT 132-1 and the source electrode SH2 of the Si-MOSFET 134-1 are connected to the same wiring pattern by wire bonding. The drain electrode DL1 of the GaN-HEMT 132-2 of the cascode element 130-2 used as the low-side switching element is also connected to this wiring pattern by wire bonding, and is connected to the lead serving as the T3 terminal.

The gate electrode GL1 of the GaN-HEMT 132-2 and the source electrode SL2 of the Si-MOSFET 134-2 of the cascode element 130-2 used as the low-side switching element are connected to a ground pattern serving as a ground by wire bonding, and connected to the noise elimination capacitor 142. It is connected to the lead that becomes the T5 terminal through the connection.

The gate electrode GH2 of the Si-MOSFET 134-1 of the cascode element 130-1, which is the high-side switching element, is connected to the wiring pattern by wire bonding, and is connected to the lead serving as the terminal T1 via the gate resistor 140-1. The gate electrode GL2 of the Si-MOSFET 134-2 of the cascode element 130-2 used as the low-side switching element is connected to the wiring pattern by wire bonding, and is connected to the lead serving as the terminal T2 via the gate resistor 140-2.

FIG. 19 is a diagram illustrating an example of a typical power module wiring pattern. It is an example 144 of a typical power module wiring pattern for applying the present invention when implementing a power module. The pattern P1 is the heat dissipation part 14 using the space between the leads. The heat radiation part 14 is provided so as to protrude into the space between the leads. The heat sink between the leads is wider than it is long. Leads 148 connected to the lead electrode pads 146 are provided around the power module as external connection electrodes, and there is a space between the lead electrode pads 146 . The heat radiation part of the wiring pattern 10 is arranged in this space so as to protrude.

The pattern P2 is a pattern in which a connection portion 28 is provided to reduce parasitic inductance in an area where there is sufficient space, that is, an area in which a long and wide wiring pattern can be formed, and which is connected in series. The connecting portion 28 may be a notch portion 30 as shown in FIG. 5(B). The pattern P3 is a pattern in which a separation slit 32 is provided in an area where there is sufficient space, that is, an area in which a wide wiring pattern is possible, for parallel connection to reduce parasitic inductance.

<Power module example A>
FIG. 20 is a diagram illustrating a power module example A150 according to the embodiment. In order to reduce the parasitic inductance, two patterns P1 and P2 are employed as shown. Cascode element 130-2 is arranged in a vertical orientation rotated 90 degrees with respect to cascode element 130-1. The wiring patterns are arranged so that wire bonding connection from the cascode element 130-1 and the cascode element 130-2 can be made in a short distance.

If the package of the switching element is connected to the wiring pattern by wire bonding and there is a parasitic inductance due to the wire and a parasitic inductance due to the wiring pattern, the switching element should be designed so that the parasitic inductance due to the wire is minimized. A wiring pattern is provided at a position where one or more wires to be bonded are the shortest, corresponding to the positions of the wire bonding terminals of the IC package.

It has a shape in which a wiring pattern is arranged around the cascode element 130-1 used as a high-side switching element. The cascode element 130-2 used as the low-side switching element also has a shape in which a wiring pattern is arranged around it. The gate electrode GH2 and the gate electrode GL2 are connected to the electrodes of the gate resistors 140-1 and 140-2 by wire bonding via wiring patterns.

Terminals T1 to T5 are connected to the leads at positions near the wiring pattern. A terminal to which nothing is connected is indicated as NC (Non-Connect). That is, the leads of the power module include the T1 terminal for inputting the gate signal to the gate resistor 140-1, the T2 terminal for inputting the gate signal for the gate resistor 140-2, the Si-MOSFET 134-1 of the high side switching element and the T3 terminal from the connection point of the Si-MOSFET 134-2 of the low side switching element, T4 terminal from the drain electrode of the GaN-HEMT 132-2 of the high side switching element, and T5-1 terminal and T5-2 terminal to be the ground. T5-3 terminal is connected. A noise elimination capacitor 142 is connected to the T4 terminal and the ground T5-3 terminal.

As measures against heat and electromagnetic waves, the cascode element 130-1 and the cascode element 130-2 are covered with an insulating heat dissipating material, and the entire surface including all wiring patterns is covered with an electromagnetic wave absorbing material. The electromagnetic wave absorbing material has high heat resistance and high heat dissipation, and is sometimes mixed with an insulating resin to prevent short circuits and improve adhesion. In this case, the entire surface may be covered with the electromagnetic wave absorbing material.

<Power module example B>
FIG. 21 is a diagram illustrating a power module example B152 according to another embodiment. To reduce parasitic inductance, patterns P1, P2 and P3 are employed as shown. The cascode element 130-1 and the cascode element 130-2 are arranged in the same direction with the sort electrode pad S2 and the drain electrode pad D1 shown in FIG. 16A facing each other. The wiring patterns are arranged so that wire bonding connection from the cascode element 130-1 and the cascode element 130-2 can be made in a short distance.

In the power module example B, the T3 terminal and the T5-2 and T5-3 terminals serving as the ground are arranged on the lower side. A T4 terminal and a T5-1 terminal serving as a ground are provided adjacent to each other, and a noise elimination capacitor 142 is connected. Such arrangement of wiring patterns is based on the concept of Kelvin connection for separating current routes.

FIG. 22 is a diagram for explaining the concept of the Kelvin connection of the power module example B152. FIG. 22A shows current route I and current route II in FIG. FIG. 22(B) shows the current route I and the current route II in FIG. 22(A) with equivalent circuits. This wiring pattern is intended to separate the current flowing from the source electrode SL2 of the cascode element 130-2 used as the low-side switching element into the T5-1 terminal side and the T5-2 terminal side. One of the T3 terminal and the T4 terminal is the input side and the other is the output side depending on whether it is a step-down type or a step-up type.

The wiring pattern serving as the source electrode SL2 and the ground acts as a common impedance for the current loop I on the T3 terminal side and the current loop II on the T4 terminal side, which are in the input/output relationship. will also grow. Therefore, the wiring pattern is designed to separate the current loops. Of course, it cannot be completely separated, but it is sufficiently effective.

As for heat and electromagnetic wave countermeasures, the cascode element 130-1 and the cascode element 130-2 are covered with an insulating heat-dissipating material, and the whole surface including all wiring patterns is covered with an electromagnetic wave absorbing material in the same manner as the power module example A150. . The electromagnetic wave absorbing material has high heat resistance and high heat dissipation, and is sometimes mixed with an insulating resin to prevent short circuits and improve adhesion. In this case, the entire surface may be covered with the electromagnetic wave absorbing material.

<Power module example C>
FIG. 23 is a diagram illustrating a power module example C154 according to yet another embodiment. In order to reduce the parasitic inductance, two patterns P1 and P2 are employed as shown. The cascode element 130-1 and the cascode element 130-2 are arranged in the same direction with the source electrode pad S2 and the drain electrode pad D1 facing each other. The wiring patterns are arranged so that wire bonding connection from the cascode element 130-1 and the cascode element 130-2 can be made in a short distance.

In the power module example C154, in addition to the concept of the Kelvin connection of the power module example B152, in order to further reduce the influence of the electromagnetic wave due to the wiring pattern, the cascode element 130-1 and the cascode element 130-2 are connected to the ground wiring pattern. The ground pattern is arranged so as to surround the As shown in FIG. 23, the T5-3 terminal and the T5-4 terminal, which serve as the ground, are connected to the lead with the lead serving as the T3 terminal interposed therebetween. Thereby, the ground pattern can be arranged so as to surround the cascode element 130-1 and the cascode element 130-2, which has the effect of suppressing electromagnetic waves.

The drain electrode DH1 of the cascode element 130-1, which is the high-side switching element, crosses the ground pattern with a space and is connected to the wiring pattern with a wire. Since it is filled, the impact is small.

As for heat and electromagnetic wave countermeasures, the cascode element 130-1 and the cascode element 130-2 are covered with an insulating heat-dissipating material, and the whole surface including all wiring patterns is covered with an electromagnetic wave absorbing material in the same manner as the power module example A150. . The electromagnetic wave absorbing material has high heat resistance and high heat dissipation, and is sometimes mixed with an insulating resin to prevent short circuits and improve adhesion. In this case, the entire surface may be covered with the electromagnetic wave absorbing material.

Although cascode-connected elements have been described for application to power modules, switching circuits in which normally-off type high-voltage GaN-HEMT elements capable of operating at high frequencies are connected in series may also be used. It may be a semiconductor element made of silicon carbide, gallium oxide, or diamond to begin with.

<Example of application to switching power supply>
FIG. 24 shows an application example 160 of the power module according to the present invention to a synchronous rectification step-down DC/DC converter. The power module 156 used here may be any of the power module example A150 shown in FIG. 20, the power module example B152 shown in FIG. 21, or the power module example C154 shown in FIG.

The input voltage DC _in has noise removed by the input capacitor C _in , becomes a rectangular wave by switching in the power module 156, and a stepped-down pulse waveform is output from between the high-side switching element and the low-side switching element. This pulse waveform is smoothed by an output inductor L _out and an output capacitor C _out to become a DC output voltage DC _out .

FIG. 25 shows an application example 162 of the power module according to the present invention to a synchronous rectification step-up DC/DC converter. The power module 156 used here may be any power module of the power module example A shown in FIG. 20, the power module example B shown in FIG. 21, or the power module example C shown in FIG.

The synchronous rectification step-up DC/DC converter 162 uses the power module in the step-down DC/DC converter 160 with the input/output relationship reversed. Noise is removed from the input voltage DC _in by the input capacitor C _in , current energy is stored in the input inductor L _in while the low side switching element is on, and even if the low side switching element is off, the high side switching element When the input inductor L _{in is turned on, the input inductor L in} works to keep the previous current value, and power is supplied so as to supplement the voltage to perform a _step-up operation. of the output voltage DC _out is obtained.

<Example of application by combining power modules>
FIG. 26 shows an application example 164 of the power module according to the present invention to a three-phase inverter. The power modules 156-1, 156-2, and 156-3 used here are any of the power module example A150 shown in FIG. 20, the power module example B152 shown in FIG. 21, or the power module example C154 shown in FIG. power module.

In an application example 164 to a three-phase inverter, three power modules 156-1, 156-2, and 156-3 are used, and the gate input of each power module 156-1, 156-2, and 156-3 is controlled. As a result, a three-phase AC voltage of U-phase, V-phase, and W-phase is output.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and applications are possible without departing from the gist of the present invention.

10 wiring pattern 12 wiring line 14 heat sink 16 element A
18 element B
20 Approximation formula of self-inductance of flat plate 22 Self-inductance of flat plate (length)
24 Self-inductance of flat plate (width)
26 Wiring pattern example A
28 connection part 30 notch part 32 separation slit 36 wiring pattern example B
40 Cylinder self-inductance approximation formula 42 Cylinder self-inductance (length)
44 cylinder self-inductance (diameter)
50 Basic circuit of synchronous step-down DC/DC converter 52 Input voltage 54 Input capacitor 56 Control unit 58 Output inductor 60 Output capacitor 62 First switching element 64 Second switching element 66 Load resistor 68 Equivalent considering parasitic inductance and parasitic capacitance Circuits 70-1, 70-2, 70-3, 70-4, 70-5 Parasitic inductances 72-1, 72-2 ESR
74-1, 74-2 Parasitic capacitance 75 Floating capacitance 76-1, 76-2 Body diode 78 Switching waveform 80 High side power MOSFET
82 Low side power MOSFET
90 Power module using electromagnetic wave absorbing material 92 Lead 94 Module substrate 100 Schematic cross-sectional view A of power module
104 Switching element 106 Wiring part 108 Wire 110 Heat dissipation material 112 Electromagnetic wave absorbing material 114 Schematic cross-sectional view B of power module
116 insulating material 120 electromagnetic wave absorber containing electromagnetic wave deflector 122 electromagnetic wave 124 electromagnetic wave deflector 130, 130-1, 130-2 cascode element 132, 132-1, 132-2 GaN-HEMT
134, 134-1, 134-2 Si-MOSFETs
136 Cascode connection equivalent circuit 138 Power module equivalent circuit 140-1, 140-2 Gate resistor 142 Noise elimination capacitor 144 Wiring pattern example for module 146 Lead electrode pad 148 Lead 150 Power module example A
152 Power module example B
154 Power module example C
156, 156-1, 156-2, 156-3 Power module 160 Application example to step-down DC/DC converter 162 Application example to step-up DC/DC converter 164 Application example to 3-phase inverter

Claims (14)

a switching element;
A power module comprising a plurality of wiring patterns arranged to surround the switching element,
At least two leads are arranged adjacent to each other in a first wiring pattern, which is one wiring pattern among the plurality of wiring patterns, and
The power module, wherein the first wiring pattern has a protruding portion arranged to protrude into the space between the two leads. In the power module according to claim 1,
The power module is a half bridge circuit comprising two switching elements,
The power module, wherein the first wiring pattern is a middle point wiring pattern corresponding to a middle point of a half bridge circuit, and the projecting portion is provided on the middle point wiring pattern. In the power module according to claim 1,
The power module is a half bridge circuit comprising two switching elements,
The first wiring pattern is a power terminal wiring pattern connected to a power terminal of one of the two switching elements, and the protrusion is provided on the power terminal wiring pattern. A power module characterized by: two switching elements;
A power module comprising a half bridge circuit comprising a plurality of wiring patterns,
At least two leads are arranged adjacent to each other in the midpoint wiring pattern corresponding to the midpoint of the half bridge circuit,
The power module according to claim 1, wherein the midpoint wiring pattern has a projecting portion arranged to project into a space between the two leads. In the power module according to any one of claims 2 to 4,
The two switching elements include a normally-on first semiconductor chip having a first drain electrode, a first source electrode and a first gate electrode, and a second drain electrode, a second source electrode and a second gate electrode. , a normally-off type capacitor disposed at a position overlapping with the first semiconductor chip when viewed in plan on the first semiconductor chip so that the first source electrode is electrically connected to the second drain electrode; and a high-side switching element and a low-side switching element comprising a cascode switch in which the first gate electrode is electrically connected to the second source electrode,
A power module, wherein the second source electrode of the high-side switching element is electrically connected to the first drain electrode of the low-side switching element. In the power module according to any one of claims 1 to 5,
The plurality of wiring patterns has a wiring pattern division serial connection structure in which recesses or notches are formed in the side portions of the wiring lines, and/or a connection in which the wiring patterns are divided into two in parallel by a separation slit or a plurality of separation slits. A power module having a pattern division parallel connection structure. In the power module according to any one of claims 1 to 6,
A power module, wherein the switching element and/or the wiring pattern are covered with an electromagnetic wave absorbing material. In the power module according to claim 7,
The power module, wherein the electromagnetic wave absorbing material has a two-layer structure in which the insulating resin is on the wiring pattern side. In the power module according to claim 7,
A power module, wherein the electromagnetic wave absorbing material is mixed with an insulating resin. In the power module according to claim 7,
A power module, wherein the electromagnetic wave absorbing material is any one of a conductive electromagnetic wave absorbing material, a dielectric electromagnetic wave absorbing material, and a magnetic electromagnetic wave absorbing material. In the power module according to claim 7,
A power module, wherein the electromagnetic wave absorber includes an electromagnetic wave deflector that changes propagation of electromagnetic waves. In the power module according to any one of claims 7 to 11,
The power module, wherein the electromagnetic wave absorbing material is an electromagnetic wave absorbing material that absorbs electromagnetic waves having a frequency corresponding to dv/dt or di/dt generated when the switching element is turned on and off. In the power module according to any one of claims 1 to 12,
A power module, wherein the switching element is a semiconductor element made of gallium nitride, silicon carbide, gallium oxide, or diamond. A switching power supply comprising the power module according to any one of claims 1 to 13.

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