JP2001085613A - Transfer mold power module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To arrange a peripheral circuit on a power circuit part through transfer mold by incorporating a gate drive IC which incorporates the control power supply 3 circuit and the level shift circuit of an IGBT and can perform control at the ground level. SOLUTION: A pattern 30 for mounting a high side IGBT and a pattern 31 for mounting a low side IGBT are formed on the opposite sides of an N wiring 33 and a shunt resistor mounting pattern 34 for detecting current is formed on the N wiring 33 wherein a lead frame pattern 35 connects the gate and emitter of the high side IGBT. Similarly, patterns 36, 37 connect the gate and emitter of the low side IGBT, respectively, and the patterns 30, 31 are connected with tie bars on the outer circumference of the lead frame at 32, 38, 39 in order to prevent one point support. Since a sufficient distance can be secured from a heat dissipation fin when the lead frame is bent upward in sealing resin, reliability is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power semiconductor module, such as an inverter, which constitutes a power conversion device, and more particularly to an IG.
The present invention relates to a structure in which a peripheral circuit such as an IGBT drive circuit and an MPU is built in a BT (Insulated Gate Bipolar Transistor) module.

[0002]

2. Description of the Related Art As one means for reducing the cost of a power semiconductor module, it has been realized to manufacture a module by transfer molding as in the case of an IC package. As a conventional example in this case, there is an example in which a schematic diagram of a sectional structure is shown in FIG.

[0003] Fig. 2 shows that IGBT and freewheeling diode (FWD) are mounted on a lead frame 11 each having six elements and four gate drive ICs (built-in various protection circuits).
Transfer molded intelligent power module, IPM (3-phase inverter module). A bare chip power element (IGBT, FWD) 14 and a bare chip gate drive IC 20 are mounted on a lead frame 11 which also serves as a power terminal 12 and a control terminal 13, and after being electrically connected with an Al wire 15, a thermosetting resin Transfer molding at 21 (first mold). Thereafter, transfer molding is performed again with the thermosetting resin 23 together with the Al radiator plate 22 (second mold). The insulation between the lead frame 11 and the Al radiator plate 22 is performed simultaneously with the thermosetting resin 23 during the second molding. Therefore, in order to reduce the thermal resistance, the thermosetting resin 23 is a resin containing a large amount of alumina filler.

As described above, according to the prior art, the components used other than the Si chip include the lead frame 11 and the Al radiator plate 2.
2, only the sealing resins 21 and 23, and the Al wires 15, and the structure is designed to reduce manufacturing costs.

[0005]

The above-mentioned conventional transfer mold type power module has the following problems in terms of achieving both high functionality of the module and reduction of the manufacturing cost, as well as module reliability.

In the case of the conventional structure shown in FIG. 2, the electric wiring pattern is formed only by the lead frame 11. Therefore,
Since the number of components is extremely small and the manufacturing process can be extremely simplified, the structure is considered in terms of manufacturing cost as described above. However, it is completely unsuitable for high functionality. Since the power system circuit pattern and the control system circuit pattern are composed of the same lead frame 11, the thickness of the lead frame 11 cannot be reduced in order to reduce the resistance of the power circuit. It is impossible to make a perfect pattern. Therefore, the scale of a control circuit that can be mounted is limited, and the circuit is not limited to a circuit that does not require a fine pattern. That is, as in the case of FIG. 2, only the gate drive IC is mounted. In addition, since the gate drive IC 20 has low power consumption, it does not need to have high heat radiation, and is a component that does not originally need to be mounted on the lead frame 11. Therefore, the module area is increased only by the area of the gate drive IC 20, and in the case of transfer mold where miniaturization is a key point, it is disadvantageous in terms of manufacturing cost.

Furthermore, in a power device that guarantees a dielectric strength of 1.5 kV or more (dielectric strength between the high voltage terminals 12 and 13 and the Al radiator plate 22), the creepage distance 195 when mounted on a fin must be increased. No. In the example of FIG. 2, the creepage distance 195 is approximately 4 mm. In the case of FIG. 2, this distance is determined by the thickness of the Al radiator plate 22. Therefore, although the thickness of the Al radiator plate 22 should be approximately 2 mm in terms of heat radiation, the plate thickness must be increased to about 4 mm, which causes an increase in manufacturing cost.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the conventional structure, the inventor of the present invention has made it possible to improve the function and cost of the module.
Furthermore, a structure that can achieve high reliability has been devised. The feature of the structure is that the following structure is adopted, based on the fact that the peripheral circuit for high performance is arranged on the power circuit part by transfer molding which is a low cost sealing form. It is.

(1) Among the circuits for controlling the IGBT module, at least three high-side IGBT control power supplies,
It incorporates a gate drive IC that has a built-in level shift circuit and can be controlled at the ground level.

(2) The lead frame constituting the power terminal is bent upward in the transfer-molded module to secure an insulation distance, and the lead frame constituting the control terminal is not bent upward.

(3) A terminal extending downward is connected to the control circuit board arranged on the power circuit, and this terminal is connected to a lead frame constituting a control terminal of the module.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view of the basic structure of the present invention. A power chip is mounted on a lead frame 11 with a thickness of 0.7 mm.
The (IGBT, FWD) 14 is solder-bonded, and the chip 14 and the lead frame 11 are connected by ultrasonic wire bonding of an Al wire 15 (wire diameter 0.3 mm). That is, the lead frame
A power circuit for supplying a main current with the power chip 11 and the power chip 14 is configured. This power circuit is connected to the lead frame 11
Is transfer-molded with resin 17 with the bottom as a bottom. Since a high voltage is applied to the power terminal 12 which is formed by a part of the lead frame 11 and supplies a main current to the outside, it is necessary to ensure a dielectric strength. Therefore, before starting up vertically outside the module, mold resin 17
Once launched vertically within. As a result, terminal 12
Creepage distance 195 can be arbitrarily set according to the applied voltage standard. In this embodiment, the distance 195 is set to about 7 mm in consideration of the dielectric strength of about 1.5 kV or more. On the other hand, the control terminal 13, which is also composed of a part of the lead frame 11, does not rise vertically in the mold resin 17, but extends horizontally from the bottom of the lead frame 11 to the outside, and then rises vertically. I have. Therefore, the distance corresponding to the distance 195 is almost only the thickness of the Al radiator plate 10, and is about 2 mm in this embodiment.

In the power circuit sealed with the resin (17), a lead frame 11 is exposed on the bottom surface, and the bottom surface is adhered to the Al plate 10 as a heat radiating plate by a resin adhesive sheet 16. The thickness of the resin adhesive sheet 16 is about 0.15 mm. With this structure, the heat generated by the power chip 14 is efficiently radiated from the Al plate 10.

A printed circuit board (PC) constituting a control circuit
B) 193 has a gate drive IC 18 and various surface mount chip components 190 mounted on both sides. The recess 194 on the upper surface of the transfer-molded power circuit is a space for components mounted on the back surface. The PCB193 has fastener-type terminals 19
2 is connected and extends downwards perpendicular to PCB193. In this structure, the PCB 193 disposed on the upper surface of the power circuit and the external control terminal 13 are connected by solder (191) bonding of the terminal 192. The gate drive IC 18 is a high breakdown voltage IC, has a built-in level shift circuit, and can control all control signals at the ground level. Further, three bootstrap circuits are configured by a chip resistor, a chip capacitor, and the like, and mounted on the PCB 193. Therefore, there is no high voltage at the control terminal. Therefore, in the present invention, there is no need to consider the insulation distance of the control terminal, and it is not necessary to raise the control terminal vertically in the module.

After the PCB 193 is mounted, the whole is sealed with the resin 19 to complete the module. In this embodiment,
Although the case where only the gate drive IC 18 is mounted as the control IC for the control circuit is shown, the incorporation of a microcomputer for generating a PWM signal and a motor position detection IC for sensorless control can be easily realized.

A more specific embodiment will be described below.

FIG. 3 shows an example of a lead frame pattern for a three-phase inverter module. It shows a schematic plan view and a schematic sectional view. The size of the lead frame is approximately 50mm x
It is 90 mm and the plate thickness is 0.7 mm as in the case of FIG. N
A pattern 30 on which a high-side IGBT is mounted and a pattern 31 on which a low-side IGBT is mounted are formed with the wiring 33 interposed therebetween. Further, a shunt resistor mounting pattern for current detection is formed on the N wiring 33. Lead frame pattern 35
This is a pattern for connecting the gate and the emitter of the high-side IGBT. Similarly, the pattern 36 is for connecting the gate of the low-side IGBT. Further, the pattern 37 is for connecting the emitter of the low-side IGBT. The patterns 30, 31 are connected to tie bars on the outer periphery of the lead frame by 32, 38, 39 in order to prevent them from being supported at one place. In this, the pattern
Reference numeral 32 serves as the external control terminal 13 at the same time as supporting the pattern 30.

FIG. 3 also shows a cross-sectional view in the long and short side directions of the lead frame. The long side direction is bent in a gull wing shape so that the creepage distance of the power terminal 390 becomes large as described above. In the present embodiment, the bending height 391 is 5 mm. On the other hand, the short side direction can no longer be bent into a gull-wing shape and serves as the bottom surface of the lead frame. Therefore, the pattern that becomes the control terminal 13
It is impossible to apply a high voltage to 32, and it is a control terminal to which only a low voltage is applied.

FIG. 4 shows an example in which the lead frame shown in FIG.
Six BT chips 50 and FWD chips 51 each, shunt resistor
52 is a schematic plan view showing the structure after mounting the device 52 and performing wire bonding. The current capacity shows the case of 15A. The size of the lead frame pattern is sufficiently larger than the chip so that heat can be sufficiently spread from the chip. When the thermal resistance from the junction to the bottom surface of the Al plate 10 was actually measured, the value was as small as 1.6 ° C./W.

FIG. 5 is a schematic top view showing the structure of the lead frame on which the power chip and the shunt resistor shown in FIG. 4 are mounted after transfer molding. Lead section 390, 3
5, 36, and 37 are exposed on the top surface of the package, and leads 32, 3
8, 39 are exposed on the lower surface of the package. The terminals of the control circuit board arranged on the upper surface are connected to the portions 35, 36, 37 exposed on the upper surface.

FIG. 6 is a schematic view showing a structure after cutting unnecessary lead portions of the structure shown in FIG. The connection portion 32 to the outer tie bar becomes the control terminal 13 so that the inner pattern 30
And it is separated like the area 60. In this state, the control circuit board 193 is connected, and the whole is sealed with the resin 19.

FIG. 7 is a schematic top view and a side view after the whole is resin-sealed and subjected to terminal treatment. Lead 39
0 is the power terminal after cutting and bending, P, N, U, V, W
The terminal 12 becomes the control terminal 13 after cutting and bending. Each terminal has a width of 3 mm, and each terminal is bent upward for easy connection to an external control circuit board. In addition, since the control terminal 13 is not bent upward inside the module, it can be seen that the control terminal 13 comes out of the module from the module bottom surface more than the power terminal. The size of the module is approximately 40 mm x 60 mm outside, and two module mounting holes 70 are provided diagonally to the module.

[0024]

The bending of the lead frame constituting the power terminal upward in the transfer-molded sealing resin has a function of sufficiently securing the distance from the radiation fins, and improves the reliability. At this time, the thickness of the radiation fins may be about the same as the conventional one, and this does not lead to an increase in cost as in the conventional example in which the thickness is increased.

On the other hand, the lead frame can be bent only at two opposing sides, and cannot be bent at the other two sides. Therefore, in order to effectively use the four sides of the lead frame, the two sides must be terminals that do not consider the insulation distance, that is, terminals to which only a low voltage is applied. Therefore, mounting a high-side power supply and a gate driver with a built-in level shift circuit in the control circuit and using a non-bendable lead frame for the control terminal has the function of effectively using the lead frame and requires a new control terminal. Therefore, there is an effect that the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a basic structure of the present invention.

FIG. 2 is a schematic cross-sectional view of a conventional structure.

FIG. 3 is a view showing one embodiment of a lead frame pattern having the structure of the present invention.

FIG. 4 is a schematic view of the lead frame of the present invention after a chip is mounted.

FIG. 5 is a schematic top view after transfer molding.

FIG. 6 is a schematic view after cutting a lead.

FIG. 7 is a schematic top view and side view of an embodiment of the structure of the present invention.

[Explanation of symbols]

10, 22: Al plate (radiator plate), 11: Lead frame, 12: Main terminal (power terminal), 13: Control terminal, 14: Power chip, 15
… Al wire, 16… Resin adhesive sheet, 17, 19, 21, 23… Transfer mold resin, 18… Gate drive IC, 190
… Chip resistors, capacitors, 191… Solder, 192… Fastener terminals, 193… Control circuit boards (printed circuit boards), 194
... Mounting area for backside mounted components, 195 ... Creepage distance, 20 ... Bare chip gate drive IC, 30 ... High-side IGBT mounting area (P
Wiring), 31 ... Low-side IGBT mounting area, 32, 38, 39 ... Pattern, tie-bar connection, 33 ... N wiring, 34 ... Shunt resistor connection area, 35 ... High-side IGBT gate, emitter connection pattern, 36 ... Low-side IGBT Gate connection pattern, 37…
Low-side IGBT emitter connection pattern, 390: Lead part to be power terminal, 391: Lead bending height, 60: Lead cut part, 70: Module mounting hole.

Claims (3)

[Claims] 1. A power circuit section having a power semiconductor element on a lead frame, a control circuit section disposed on an upper surface of the resin-sealed power circuit section for controlling the power circuit section, and a module bottom section. An external input / output terminal connected to the power circuit section and the control circuit section formed by the lead frame, wherein the lead frame is close to the metal base via an insulator. In the power semiconductor module which is arranged and is entirely resin-sealed with the metal base as a bottom surface, the input / output terminal (power terminal) connected to the power circuit is separated from the metal base in the module. After being launched, it is further bent substantially parallel to the outside of the metal base,
On the other hand, the power semiconductor module is characterized in that the input / output terminals (control terminals) connected to the control circuit section are led out of the module from the bottom surface of the lead frame substantially parallel to the metal base without being bent. 2. The power semiconductor module according to claim 1, wherein the power terminal is formed on one or two opposite sides of the lead frame, and the control terminal is formed on another opposite one or two sides. A power semiconductor module characterized by being performed. 3. The power semiconductor module according to claim 1, wherein a terminal is connected to at least one side of the control circuit board, and the terminal extends downward substantially perpendicular to the control circuit board, and a part of the lead frame. A power semiconductor module, wherein the power semiconductor module is connected to the control terminal.