JP2935631B2 - Power module - Google Patents

Abstract

PURPOSE:To provide a power module, wherein the prevention of the erroneous operation in a drive control circuit and the maintenance of excellent heat radiating property can be made compatible, and which can readily obtain the compact configuration and the cost reduction. CONSTITUTION:A metal substrate 1 having a first insulating layer 2 on one surface, a second metal substrate 3 arranged on a part of the exposed surface of the insulating layer 2, an insulating layer 4 arranged on the exposed surface of the metal substrate 3 and a wire 20, which keeps the metal substrate 3 at the grounding potential, are provided. A power switching element group 6 is arranged on the exposed surface of the insulating layer 2. A pre-driver IC 8 is arranged on the exposed surface of the insulating later 4. The switching noise from the power switching element group 6 is shielded with the metal substrate 3 kept at the grounding potential. Therefore, the erroneous operation of the control circuit can be prevented. The power switching element group 6 is arranged on the heat radiating metal substrate 1 only through the insulating layer 2. Therefore, the heat radiating effect can be sufficiently enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power module in which a power switching element group and a control circuit for driving and controlling the power switching element group are arranged on a common metal substrate via an insulating layer. The present invention relates to a power module suitable for an electric motor driving inverter device and the like.

[0002]

2. Description of the Related Art In recent years, when a relatively small-capacity electric motor is used in home electric appliances or the like, a power module including a power switching element group and a control circuit for driving and controlling the power switching element group is provided in an inverter device for driving the motor. It is becoming widely used.

[0003] A power switching element including such a power switching element group and a circuit for driving and controlling the power switching element group.
In the prior art of the module, power switching elements and a circuit for driving and controlling the power switching elements are arranged on the same insulated metal substrate, and the metal substrate is connected to a ground potential portion, whereby power switching is performed. The problem of malfunction of the control circuit caused by noise from the element group was solved.

[0004] Such a conventional motor driving power module will be described with reference to FIG. In the prior art shown in FIG. 6, 1 is a first metal substrate, 2 is a first insulating layer, 3 is a second metal substrate, and 4 is a second insulating layer. , Stacked and joined.

Next, reference numeral 6 denotes a power switching element group.
8 is a pre-driver IC composed of a plurality of power switching elements.
Drives the power switching element group 6.
The power switching element group 6 and the pre-driver IC 8 are bonded on the wiring metal layer 5 patterned on the second insulating layer 4 and connected by the wires 20 so as to obtain a desired circuit connection. Have been.

FIG. 7 is a circuit diagram showing a case where such a power module is applied to a three-phase brushless motor driving device. A commercial AC power supply 13, a DC converter 14, and a control circuit 1 are shown.
5, a driving circuit 16, a power switching element group 6 composed of six power switching elements, and a three-phase brushless motor 17. Here, the control circuit 1
5 and the drive circuit 16 are configured as a pre-driver IC 8.

FIGS. 8 and 9 are block diagrams of the control circuit 15.
First control circuit 15a, flip-flop circuit 15
b, a second control circuit 15c, a comparator 15d, and a triangular wave oscillation circuit 15e. Of these, the flip-flop circuit 15b and the comparator 15d are circuit elements that are particularly sensitive to noise. Therefore, the input wiring group 15f for these circuit elements must be designed not to particularly pick up noise. For this reason, the drawing is drawn with thick lines.

FIG. 8 shows a triangular wave oscillation circuit 15e,
This is an example in which the input wiring group 15f of the circuit element sensitive to noise is integrated in the pre-driver IC 8 together. FIG. 9 shows a pre-driver IC in which a triangular wave oscillation circuit 15e and an input wiring group 15f of circuit elements sensitive to noise are integrated.
In place of the triangular wave oscillation circuit 15e, an independent pre-driver IC 8a is used in place of the triangular wave oscillation circuit 15e.
In this example, a part of the input wiring group 15f of the element that is sensitive to noise is not integrated, and the input wiring group 15g is formed of wires.

Here, the circuit element which is sensitive to noise is a circuit element having an amplitude of about 0.1 [V] and a pulse width of about 100 [ns] which may cause a malfunction. As described above, flip-flops, operational amplifiers, comparators, and the like are applicable.

In the case of such a power module for a motor that handles a commercial power supply, the predriver IC 8 malfunctions as described above due to noise caused by voltage fluctuations generated when the power switching element group 6 is turned on and off. Sometimes. The malfunction is more likely to occur as the power supply voltage increases, and the power switching element group 6
Is more likely to occur in the case of an element having a higher switching speed, such as IGBT and MOS.

When this is viewed on the pre-driver IC 8 side,
The malfunction occurs most sensitively when noise is applied to the input wiring group 15e of a circuit element that is sensitive to noise, such as a flip-flop, an operational amplifier, and a comparator. This is because the output is not inverted by a small amount of noise in a normal C-MOS logic, but the output of a flip-flop, an operational amplifier, a comparator and the like is easily inverted even by a small amount of noise, and malfunctions. is there.

Therefore, in order to prevent these malfunctions, the power module according to the prior art, as shown in FIG.
A hole 12 for grounding the substrate is provided in the second insulating layer 4,
In general, a method of connecting the metal substrate 3 to a portion of the metal wiring layer 5 forming a power ground (a common potential portion in a circuit system of the device) by bonding with a wire 20 and grounding the metal substrate 3 is used. According to this, since the second metal substrate 3 is fixed at a constant potential, the switching noise of the power switching element group 6 is reduced by the pre-driver IC 8.
, And the possibility of malfunction can be sufficiently suppressed.

On the other hand, the power switching element group 6 needs to be cooled by a radiation fin in order to handle power as its name implies. However, in general, the potential of the radiation fin depends on safety and other aspects. And must be floating with respect to the power ground.
Therefore, for this reason, in the prior art, as shown in FIG.
The first metal substrate 1 is insulated from the second metal substrate 3 by the first insulating layer 2.

As related techniques of this kind, Japanese Patent Application Laid-Open Nos. 3-218060 and 4-34
No. 6260 can be cited.

[0015]

According to the prior art, in a power module in which a power switching element group and a control circuit are arranged on a common metal substrate via an insulating layer, a control circuit based on switching noise from the power switching element group is provided. No consideration has been given to both the prevention of malfunction and the retention of good heat dissipation, and there has been a problem in terms of increasing the size of the entire power module and reducing the cost.

That is, generally, the insulating layer has low thermal conductivity, which is a major factor in increasing the thermal resistance in the heat dissipation system. However, in the related art, as is apparent from FIG. 6, the first insulating layer 2 and the second insulating layer 4 are used as the insulating layers, whereby the problem of malfunction due to noise is temporarily solved. However, since two insulating layers are required, the thermal resistance tends to increase, and it is difficult to obtain sufficient heat radiation. As a result, large heat radiation fins are required. The cost is likely to increase. Further, in the prior art, the cost of the module is increased in that two insulating layers are required.

An object of the present invention is to provide a power module capable of simultaneously preventing malfunction in a drive control circuit and maintaining good heat dissipation, and which can easily be reduced in size and cost. It is in.

[0018]

SUMMARY OF THE INVENTION The object of the present invention is to provide a dielectric isolation device.
In a power module including a drive control circuit composed of an integrated circuit having a structure and a power switching element group driven and controlled by the drive control circuit, a metal substrate having a first insulating layer on one surface; A conductive layer composed of a polycrystalline semiconductor layer disposed on a part of the exposed surface of the insulating layer ;
A second insulating layer disposed on the exposed surface of serial conductive layer, provided the conductive means to maintain the conductive layer to the ground potential, the power switching element group are arranged on the exposed surface of the first insulating layer,
The conductive layer has a large number of integrated circuits constituting the drive control circuit.
A crystalline semiconductor layer, wherein the second insulating layer is integrated
Consists of an insulating film to make the circuit a dielectric isolation structure
Thus, the present invention is achieved by disposing the drive control circuit on the exposed surface of the first insulating layer .

[0019]

The first insulating layer allows the power switching element group to immediately come into contact with the first metal substrate only through the first insulating layer. The first insulating layer is provided between the power switching element group and the first metal substrate. It works to minimize the increase in thermal resistance.
Therefore, the heat generated in the power switching element group is effectively transmitted to the first metal substrate, so that a sufficient cooling effect can be exerted.

The conductive layer kept at the ground potential
It is located between the drive control circuit and the first metal substrate and serves as an electrostatic shield. Therefore, noise from the power switching element group is effectively blocked by this conductive layer, and the possibility that the drive control circuit malfunctions can be sufficiently eliminated.

As a result, it is possible to prevent malfunction in the drive control circuit and to maintain good heat dissipation, thereby achieving downsizing and cost reduction.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a power module according to the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows a first embodiment of the present invention. In this embodiment, first, on a first metal substrate 1 which performs a heat radiation function and a function as a substrate of the entire module, as in the prior art, First insulating layer 2
Is provided. In this embodiment, the power switching element group 6 is formed on the exposed surface of the first insulating layer 2 on the first metal substrate 1 (the surface opposite to the surface in contact with the first metal substrate 1). ) Is mounted on the exposed surface of the first insulating layer 2 by means of the metal wiring layer 5a formed in FIG.

On the other hand, also in this embodiment, as in the prior art, the substrate ground hole 1 provided in the second insulating layer 4 is provided.
2 has a second metal substrate 3 which is connected to a metal wiring layer 5 by a wire 20 via a wire 2 to form a conductive layer maintained at the ground potential. The metal substrate 3 is not disposed on the entire exposed surface of the first insulating layer 2 but is disposed only on a portion of the first insulating layer 2 where the power switching element group 6 is not disposed, as shown in FIG.

The exposed surface of the second insulating layer 4 provided on the second metal substrate 3 (the surface opposite to the surface in contact with the second metal substrate 3) is provided with the power switching element. A pre-driver IC 8 in which a drive control circuit for driving and controlling the group 6 is integrated is provided. The pre-driver IC 8 is an integrated IC that also incorporates a triangular wave oscillation circuit 15e as shown in FIG.

As a result, in this embodiment, first, in this embodiment, the pre-driver IC 8 and the power switching element group 6 are not arranged on the same substrate, but are arranged on an independent metal substrate. Since the effect of the switching noise from the power switching element group 6 is suppressed by the shielding function of the second metal substrate 3 held at the potential, the malfunction of the pre-driver IC 8 can be reliably prevented.

At the same time, in this embodiment, the power switching element group 6 is directly disposed on the surface of the first metal substrate 1 for heat radiation only with the first insulating layer 2 interposed therebetween.
Since the thermal resistance in the heat transfer path from the power switching element group 6 to the first metal substrate 1 is significantly reduced as compared with the related art, the heat radiation effect can be sufficiently improved.

Therefore, according to this embodiment, it is possible to prevent malfunction in the drive control circuit and to maintain good heat dissipation in the power switching element group, and it is easy to reduce the size and cost. Obtainable.

FIG. 2 shows a second embodiment of the present invention.
As shown in FIG. 9, this embodiment uses a pre-driver IC 8a having an externally attached triangular wave oscillating circuit 15e. For this reason, the pre-driver IC 8a and the triangular wave oscillating circuit 15e are used.
e are provided on the second metal substrate 3 respectively.
Is disposed on the exposed surface of the insulating layer 4. These are connected by an input wiring group 15g.

Therefore, according to this embodiment, the malfunction prevention in the drive control circuit and the good heat radiation in the power switching element group can be achieved at the same time, and the miniaturization and the cost reduction can be easily achieved. Obtainable.

Next, FIG. 3 shows a third embodiment of the present invention.
As the pre-driver IC, an integrated circuit having a dielectric isolation structure is used, and the conductive layer formed of the second metal substrate 3 in the above embodiment is formed of a polycrystalline semiconductor layer constituting the integrated circuit having the dielectric isolation structure. In this embodiment, the second insulating layer 4 is formed of an insulating film for the above-mentioned dielectric isolation structure. In FIG. 3, reference numeral 7 denotes a pre-driver IC comprising an integrated circuit having this dielectric isolation structure. .

The pre-driver IC 7 includes a polycrystalline semiconductor layer 7a serving as a base. On one surface of the pre-driver IC 7, an electrically independent island-shaped single crystal semiconductor region 7b separated by an insulating film 7c is provided. A plurality of circuit devices shown in FIG. 8 are formed on the main surface of the single-crystal semiconductor region 7b, so that the drive control necessary to drive and control the power switching element group 6 is formed. The circuit is configured.

The polycrystalline semiconductor layer 7 a is disposed directly on the surface of the first metal substrate 1 via the first insulating layer 2, similarly to the power switching element group 6. The second metal substrate 3 and the second insulating layer 4 used in the embodiment shown in FIGS. 1 and 2 are both arranged. Absent.

Therefore, according to this embodiment, the potential of the polycrystalline semiconductor layer 7a is fixed to the ground potential by being connected to the ground potential point by the wire 20.
As a result, the polycrystalline semiconductor layer 7a functions as a conductive layer for shielding, and effectively blocks the switching noise from the power switching element group 6, so that the redriver I
The influence of noise on C7 is suppressed, and as a result, malfunction of predriver IC7 can be reliably prevented.

According to the embodiment of FIG. 3, the second metal substrate 3 used in the embodiment of FIGS.
The second insulating layer 4 becomes unnecessary, and the pre-driver I
C7 is also disposed on the first metal substrate 1 for heat dissipation as in the case of the power switching element group 6, so that the heat dissipation effect including the pre-driver IC 7 can be improved, and as a result, the entire power module can be improved. Size reduction and cost reduction can be easily obtained.

FIG. 4 shows the details of the pre-driver IC7. As shown in FIG. 4, a portion of the portion exposed on the surface of the polycrystalline semiconductor layer 7a and a portion of the main surface of the single crystal semiconductor region 7b are shown. Is provided with an insulating layer 22, whereby
A wiring layer 23 in contact with the polycrystalline semiconductor layer 7a and an input wiring layer 15g of a device sensitive to noise are formed. Then, the wiring layer 23 is connected to the power ground by the wire 20, whereby the polycrystalline semiconductor layer 7a
Is fixed to the ground potential.

FIG. 5 shows a pre-driver IC having a dielectric isolation structure and a dielectric isolation substrate type integrated circuit.
In another embodiment, in the figure, 70 represents a pre-driver IC according to this embodiment. This pre-driver IC
Numeral 70 includes a first single-crystal semiconductor layer 24 serving as a substrate, and a plurality of electrically isolated island-shaped single-crystal semiconductor regions 7b separated by insulating films 7c and 7d are formed on the surface thereof. Then, on the main surface, various circuit devices shown in FIG. 8 are formed, and a drive control circuit necessary to drive and control the power switching element group 6 is configured.

The pre-driver IC 70 is formed by bonding the other surface of the single crystal semiconductor layer 24 to the surface of the metal wiring layer 5 formed on the surface of the first insulating layer 2.
It will be arranged on the first metal substrate 1 via the first insulating layer 2. Then, the metal wiring layer 5 is connected to a ground potential by a wire 8.

Therefore, in the embodiment shown in FIG. 5, the single crystal semiconductor layer 24 is separated by the insulating film 7d to form a dielectric isolation substrate, and its potential is fixed to the ground potential. 24 serves as a shielding function for the circuit device formed in the single crystal semiconductor region 7b and the input wiring layer 15g of the element sensitive to noise, and the same effect as that of the embodiment of FIG. 3 can be obtained. .

[0039]

According to the present invention, malfunction of the control circuit due to switching noise from the power switching element group can be prevented, and the second metal substrate and the second insulating layer below the power switching element group become unnecessary. Therefore, it is possible to arrange the power switching element group directly on the substrate for heat dissipation to enhance the heat dissipation effect, and to easily realize the miniaturization and cost reduction of the whole power module.

Further, according to the present invention, the dielectric isolation structure of the drive control circuit such as the pre-driver circuit is utilized, and it is not necessary to separately provide the second conductive layer and the second insulating layer, so that the cost can be reduced. Can be further achieved.

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of a power module according to the present invention.

FIG. 2 is a side view showing a second embodiment of the power module according to the present invention.

FIG. 3 is a side view showing a third embodiment of the power module according to the present invention.

FIG. 4 shows a pre-driver I according to a third embodiment of the present invention.
It is side sectional drawing which shows an example of C.

FIG. 5 is a pre-driver IC according to a third embodiment of the present invention;
It is a sectional side view which shows another example of.

FIG. 6 is a side view showing a conventional example of a power module.

FIG. 7 is a block diagram showing an example of a power module on which a three-phase brushless motor driving device is mounted.

FIG. 8 is a block diagram showing an example of a drive control circuit in a power module equipped with a three-phase brushless motor drive device.

FIG. 9 is a block diagram showing another example of the drive control circuit in the power module equipped with the three-phase brushless motor drive device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st metal substrate 2 1st insulating layer 3 2nd metal substrate 4 2nd insulating layer 5 metal wiring layer 6 power switching element group 7 predriver IC 7a comprised by the dielectric isolation type integrated circuit 7a polycrystalline semiconductor Layer 7b Single-crystal semiconductor 7c, 7d Insulating film 8, 8a Predriver IC 12 Substrate ground hole 13 Commercial AC power supply 14 DC converter 15 Control circuit 15a First control circuit 15b Flip-flop circuit 15c Second control circuit 15d Comparison Device 15e Triangular wave oscillation circuit 15f Input wiring group 15g Input wiring group 16 Drive circuit 17 Three-phase brushless motor 20 Wire 21 Input wiring group of element sensitive to noise 22 Insulating layer 23 Wiring layer 24 Single crystal semiconductor layer 70 Dielectric separating substrate Second pre-driver IC used

Continuation of front page (72) Inventor Masato Miura 3-1-2, Bentencho, Hitachi City, Ibaraki Prefecture Inside Tachihara-cho Electronic Industry Co., Ltd. (56) References JP-A-5-167006 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 25/04

Claims (2)

(57) [Claims] 1. A power module comprising a drive control circuit composed of an integrated circuit having a dielectric isolation structure and a power switching element group driven and controlled by the drive control circuit, wherein a first insulating layer is provided on one surface. And a polycrystalline semiconductor disposed on a part of the exposed surface of the first insulating layer.
A conductive layer made of the body layer, a second insulating layer disposed on the exposed surface of the conductive layer, provided the conductive means to maintain the conductive layer to the ground potential, the first insulating layer to the power switching element group The conductive layer is disposed on the exposed surface of
A crystalline semiconductor layer, wherein the second insulating layer is integrated
Consists of an insulating film to make the circuit a dielectric isolation structure
The power module , wherein the drive control circuit is arranged on the exposed surface of the first insulating layer . 2. The invention according to claim 1, wherein the drive control circuit includes a pre-driver circuit and an input wiring group of an element sensitive to noise, and the input wiring group is integrated with the pre-driver circuit. A power module characterized in that: