JP2003086763A - Semiconductor power module and power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor power module of higher breakdown voltage with no increase in heat resistance, and to provide a power converter comprising the semiconductor power module. SOLUTION: Related to a semiconductor power module 5, a semiconductor element 1 is jointed to an electric circuit pattern 31 provided on an insulating substrate 2 which is jointed to a metal substrate 4. A second metal substrate 32 of the same electric potential as the collector electrode is disposed at a symmetric position, viewed from the electric circuit pattern 31 connected to the collector electrode, of the first metal substrate 4 of a ground electrode, to relax the maximum electric field for improved insulating capability. Thus, the breakdown voltage is improved with no increase in heat resistance of the semiconductor power module.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an IGBT and an IEG.
The present invention relates to a semiconductor power module such as T, and a power converter including the semiconductor power module.

[0002]

2. Description of the Related Art In recent years, as semiconductor power modules such as IGBTs and IEGTs have become higher in voltage, insufficient dielectric strength of semiconductor power modules and partial discharge have emerged as problems.

FIG. 7 shows the result of electric field analysis in the conventional semiconductor power module. The maximum electric field is generated in the silicon gel at the end of the junction surface of the electric circuit pattern (indicated as a collector electrode in FIG. 7) connected to the insulating substrate and the collector electrode. In the vicinity of this end portion indicated by an arrow as a high electric field portion in FIG. 7, a sharp portion due to etching residue of the electric circuit pattern and a residual void that cannot be completely removed by the removal method are likely to occur, resulting in deterioration of insulation reliability. Cheap.

[0004]

As described above, in the conventional semiconductor power module, a high electric field is generated at the junction end portion of the electric circuit pattern and the insulating substrate, and a sharp portion due to etching residue of the electric circuit pattern, The increase in the dielectric strength is hampered by the fact that residual voids that cannot be eliminated by the removal method are likely to occur. Simply by increasing the thickness of the insulating substrate, it is possible to increase the voltage of the semiconductor power module, but on the other hand, the thermal resistance of the semiconductor power module is greatly increased.

The upper limit of usable temperature of the semiconductor device is determined, and in order to cover the decrease of the cooling capacity due to the increase of the thermal resistance of the semiconductor power module, the cooling device is increased in size to enhance the cooling capacity, or the semiconductor element is cooled. It is necessary to suppress the current carrying capacity and the generated loss. In either case, the power density of the power converter composed of the semiconductor power module will decrease.

Therefore, an object of the present invention is to provide a semiconductor power module having an improved withstand voltage without increasing thermal resistance, and a power converter composed of this semiconductor power module.

[0007]

A semiconductor power module according to the present invention is a semiconductor power module in which a semiconductor element is bonded to a conductor layer of an electric circuit pattern provided on an insulating substrate, and the insulating substrate is bonded to a metal substrate. , The second metal layer is arranged at a position symmetrical to the first metal substrate, which is the metal substrate bonded to the insulating substrate, as seen from the conductor layer of the electric circuit pattern.
It is characterized by arranging the metal substrate of.

As described above, by arranging the second metal substrate at a position symmetrical to the first metal substrate (base substrate) as viewed from the conductor layer of the electric circuit pattern, the maximum electric field is relaxed, The insulating ability can be improved.

The semiconductor power module according to the present invention is a semiconductor power module in which a semiconductor element is joined to a conductor layer of an electric circuit pattern provided on an insulating substrate, and the insulating substrate is joined to a metal substrate. The second metal substrate having a predetermined opening surface is arranged at a position symmetrical with respect to the first metal substrate which is the metal substrate joined to the insulating substrate when viewed from the conductor layer of.

Thus, by arranging the second metal substrate having a predetermined opening surface at a position symmetrical with respect to the first metal substrate (base substrate) when viewed from the conductor layer of the electric circuit pattern, The maximum electric field can be alleviated, the insulating ability can be improved, and the wiring connection to the semiconductor element by the bonding wire can be performed through the opening surface.

The power converter according to the present invention is characterized by being constituted by a semiconductor power module corresponding to any of the above.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
2A and 2B show a configuration of a semiconductor power module according to the embodiment of the present invention, wherein FIG. 1A is a perspective view and FIG. 1B is a sectional view of a main part. In FIG. 1, the semiconductor power module 5
Is a semiconductor element 1, an insulating substrate 2, a first metal substrate (shown as a ground electrode in the figure) 4 as a ground electrode, and an electric circuit pattern connected to the collector electrode (shown as a collector electrode in the figure). ) 31 and a second metal substrate 32 (shown as a collector electrode in the figure) 32 having the same potential as the collector electrode.

That is, in the semiconductor power module 5 which constitutes a power converter, for example, the semiconductor element 1 is bonded to the electric circuit pattern 31 provided on the insulating substrate 2, and the insulating substrate 2 is connected through the electric circuit pattern for connection. And is bonded to the first metal substrate 4.

By arranging the second metal substrate 32 having the same potential as the collector electrode at a symmetrical position of the first metal substrate 4 which is the ground electrode as viewed from the electric circuit pattern 31 connected to the collector electrode. , The maximum electric field is relaxed, and the insulation capability is improved. The second electrode of the same potential as this collector electrode
The metal substrate 32 of does not need to be perfectly symmetrical,
It is effective if they exist in positions that are almost symmetrical.

In order to show the effect of the first embodiment, FIG. 2 shows the result of electric field analysis, and FIG. 3 shows a voltage of 1 kV applied to the collector electrode.
Regarding the maximum electric field strength on the interface between the insulating substrate 2 and the silicon gel 6 when the voltage is applied, the insulating substrate 2 and the second metal substrate 3
The characteristic diagram by the distance distance from 2 is shown. As can be seen from FIG. 2, the electric field is almost equal in the vicinity of the end portion of the joint surface of the electric circuit pattern 31 connected to the insulating substrate 2 and the collector electrode, and compared with the conventional example of FIG. The maximum electric field is relaxed. In addition, as shown in FIG. 3, when the thickness of the insulating substrate 2 is 0.5 mm, the maximum electric field strength E decreases when the second metal substrate 32 is at a substantially symmetrical position, that is, when the distance H is about 1 mm. ing.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
2A and 2B show a configuration of a semiconductor power module according to the embodiment of the present invention, wherein FIG. 1A is a perspective view and FIG. 1B is a sectional view of a main part. In FIG. 4, the semiconductor power module 5
Is a semiconductor element 1, an insulating substrate 2, a first metal substrate (shown as a ground electrode in the figure) 4 as a ground electrode, and an electric circuit pattern connected to the collector electrode (shown as a collector electrode in the figure). ) 31 and a second metal substrate 32 (shown as a collector electrode in the figure) 32 having the same potential as the collector electrode.

That is, for example, in the semiconductor power module 5 which constitutes a power converter, the semiconductor element 1 is bonded to the electric circuit pattern 31 provided on the insulating substrate 2, and the insulating substrate 2 is connected through the electric circuit pattern for connection. And is bonded to the first metal substrate 4.

Then, as viewed from the electric circuit pattern 31 connected to the collector electrode, a second opening having a predetermined opening surface at the symmetrical position of the first metal substrate 4 as the ground electrode and having the same potential as the collector electrode. A metal substrate 32 is arranged. The illustrated one shows a case where the size of the opening surface of the second metal substrate 32 is equal to or larger than the projection surface of the outer periphery of the electric circuit pattern 31. As seen from the electric circuit pattern 31 thus connected to the collector electrode, the first metal substrate 4 serving as the ground electrode
By arranging the second metal substrate 32 having the same electric potential as the collector electrode at a symmetrical position of and at a position outside the projection surface on the outer periphery of the electric circuit pattern 31, the maximum electric field is relaxed,
The insulation capacity is improved. The arrangement of the second metal substrate 32 having the same potential as that of the collector electrode does not have to coincide with the projection surface of the outer periphery of the electric circuit pattern 31, but is effective as long as it exists at a position outside thereof.

In order to show the effect of the second embodiment, FIG. 5 shows the result of electric field analysis, and FIG. 6 shows a voltage of 1 kV applied to the collector electrode.
A characteristic diagram of the maximum electric field strength on the interface between the insulating substrate 2 and the silicon gel 6 when a voltage is applied is shown by the distance between the projection surface on the outer periphery of the electric circuit pattern 31 and the second metal substrate 32. As can be seen from FIG. 5, the electric field is almost uniform in the vicinity of the end portion of the joint surface of the electric circuit pattern 31 connected to the insulating substrate 2 and the collector electrode, and compared with the conventional example of FIG. The maximum electric field is relaxed. Further, as shown in FIG. 6, a projection surface on the outer periphery of the electric circuit pattern 31,
The maximum electric field strength E decreases in the range where the distance W from the second metal substrate 32 is 0 to 2 mm.

As described above, since the projection surface is opened and the opening surface is formed in the second metal substrate 32 having the same potential as the collector electrode, the bonding wire with the semiconductor element 1 is formed through the opening surface. Wiring connection and removal of voids by vacuum desorption can be easily performed.

In the above description, the second metal substrate 3
The case where the size of the opening surface of No. 2 is equal to or larger than the projection surface of the outer periphery of the electric circuit pattern 31 has been described. May be smaller.

(Other Embodiments) In the above-described first or second embodiment, the second metal substrate 32 having the same potential as the collector electrode is the wiring conductor of the main circuit or the wiring pattern of the gate circuit substrate. If it can also serve as a part, the inductance of the internal wiring of the package can be reduced at the same time as the wiring becomes wider.

In the first or second embodiment described above, the case where the high voltage is not applied to the emitter electrode but the voltage is applied only to the collector electrode has been described.
The same idea can be applied and implemented even when a high voltage is applied to the emitter electrode.

[0025]

As described above, according to the semiconductor power module of the present invention, the withstand voltage can be improved without increasing the thermal resistance of the semiconductor power module. Conversely, if the semiconductor power modules have the same withstand voltage, the thermal resistance can be reduced, and as a result, the power density of the power converter can be improved.

[Brief description of drawings]

1A and 1B are views showing a configuration of a semiconductor power module according to a first embodiment of the present invention, in which FIG. 1A is a perspective view and FIG.
Is a cross-sectional view of the main part.

FIG. 2 is a diagram showing a result of an electric field analysis for showing the effect of the first embodiment.

FIG. 3 is a diagram showing the characteristics of the maximum electric field strength depending on the distance between the insulating substrate and the second metal substrate, in order to show the effect of the first embodiment.

4A and 4B are diagrams showing a configuration of a semiconductor power module according to a second embodiment of the present invention, in which FIG. 4A is a perspective view and FIG.
Is a cross-sectional view of the main part.

FIG. 5 is a diagram showing a result of an electric field analysis for showing an effect of the second embodiment.

FIG. 6 is a diagram showing the characteristics of the maximum electric field strength depending on the distance between the projection surface on the outer periphery of the electric circuit pattern and the second metal substrate, for showing the effect of the second embodiment.

FIG. 7 is a diagram showing a result of electric field analysis in a conventional example.

[Explanation of symbols]

1 ... Semiconductor element 2 ... Insulating substrate 4 ... First metal substrate that is a ground electrode 5 ... Semiconductor power module 6 ... Silicon gel 31 ... Electric circuit pattern connected to collector electrode 32 ... A second metal substrate having the same potential as the collector electrode

Claims (5)

[Claims] 1. In a semiconductor power module in which a semiconductor element is bonded to a conductor layer of an electric circuit pattern provided on an insulating substrate, and an insulating substrate is bonded to a metal substrate, the insulating substrate is viewed from the conductor layer of the electric circuit pattern. A semiconductor power module, wherein a second metal substrate is arranged at a position symmetrical to the first metal substrate, which is the metal substrate bonded to. 2. A semiconductor power module in which a semiconductor element is joined to a conductor layer of an electric circuit pattern provided on an insulating substrate, and an insulating substrate is joined to a metal substrate, as viewed from the conductor layer of the electric circuit pattern. 2. A semiconductor power module, wherein a second metal substrate having a predetermined opening surface is arranged at a symmetrical position of the first metal substrate which is the metal substrate bonded to. 3. The semiconductor power module according to claim 1, wherein the second metal substrate also serves as a wiring conductor of a main circuit. 4. The second metal substrate also serves as a part of a wiring pattern of the gate circuit substrate.
Alternatively, the semiconductor power module according to claim 2. 5. A power converter comprising the semiconductor power module according to any one of claims 1 to 4.