JP2009088218A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent cracking of a ceramic substrate used in a high voltage power module exceeding 1 kV or a power module where the operating temperature of a semiconductor exceeds 100°C because heat dissipation and insulation between a semiconductor element and a heat dissipator are important characteristics in these power modules, and to provide a semiconductor device which dissipates heat efficiently while exhibiting insulation characteristics. <P>SOLUTION: The semiconductor device comprises a heat dissipation member, a metal member containing an electronic component including a semiconductor in a case and mounting the electronic component, and an electrode for conducting a current, wherein the metal member, a ceramic powder layer, and the heat dissipation member having a coarse surface portion are sequentially brought into contact with each other. A degassing layer is provided in the ceramic powder layer of the semiconductor device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device, and more particularly to a power semiconductor module device such as an inverter, a thyristor, and a power module on which a power semiconductor is mounted, and a manufacturing method thereof.

  Power semiconductor module devices (hereinafter referred to as “power modules”) are used in various home appliances such as air conditioners, elevators, industrial machines, trains, hybrid electric vehicles, electric vehicles, and other inverter-controlled power devices, and are referred to as power devices. Has been.

  Conventionally, power semiconductor modules applied to relatively large-capacity power modules usually have a case in which an outer case made of insulating resin and a heat sink made of a metal plate are combined. Each electronic component is housed. This heat radiating body is mounted on a cooler such as a cooling heat radiating fin or a water-cooled heat radiating body via a heat conductive grease.

  Inside the outer case, a ceramic insulating substrate having a metal plate (foil) formed on the front and back is joined to the heat radiator by solder. Normally, the metal plate (foil) on the back side (heatsink side) covers almost the entire surface of the ceramic insulating substrate, and the circuit pattern is formed by the metal plate (foil) on the front side (side where the heatsink is not soldered). The ceramic metal insulation circuit board. On the circuit pattern, a power semiconductor element, a chip component and the like are soldered. Further, the external connection terminals arranged in the outer case and the circuit pattern are connected by bonding wires.

  After the electronic parts are installed, the inside of the outer case is filled with a sealing resin such as silicon gel or epoxy resin. The sealing resin is further sealed with a solid resin such as an epoxy resin, and a terminal holder made of the same or different material as the outer case is fixed on the solid resin.

  In the power module having the above-described structure, heat dissipation and insulation between the semiconductor element and the heat sink are important characteristics when the power module exceeds 1 kV or when the semiconductor operating temperature exceeds 100 ° C. Yes.

  For this reason, in the conventional configuration, a ceramic substrate made of a material such as alumina or aluminum nitride and having excellent thermal conductivity and insulating characteristics is used as the insulating substrate. Further, heat conductive grease is interposed between the radiator and the cooler so that heat is efficiently released from the radiator to the cooler. The radiator and the cooler are usually fixed with screws.

  In Patent Document 1, in order to improve the electrical characteristics (especially insulation), durability, and reliability of the conventional configuration, a metal plate (mounting conductor) between which a semiconductor element is disposed and a radiator is provided. Are connected by a sheet-like heat dissipating insulator, and an insulating resin is disposed in contact with an end of the metal plate.

  With the structure of Patent Document 1, it is possible to obtain both a thermal conductivity of 3 W / m · K or more and a dielectric breakdown strength of 30 kV / mm or more at the connection portion between the metal plate and the heat dissipation means.

Further, in comparison with the conventional structure, a resin sheet-like heat dissipating insulator is arranged in place of the conventional ceramic insulating substrate, and the end of the metal plate is sealed with an insulating resin in order to ensure insulation characteristics. It has stopped. As a result, the conventional ceramic insulating substrate eliminates the problem that the ceramic insulating substrate breaks due to thermal shock or the like and causes dielectric breakdown.

  In Patent Document 2, as a power module that can ensure sufficient heat dissipation performance with a simple structure, a metal plate (wiring) on which a semiconductor element or the like is disposed and a radiator (heat sink) are made of an insulating adhesive (insulating resin). ). This makes it possible to make friendly use in fields where the installation space for power modules is large, such as electric vehicles and hybrid cars. In particular, the semiconductor element temperature is about 150 to 250 ° C., the power supply voltage used is 200 to 750 V, and the maximum voltage is about 700 to 1500 V. It is expected to be used for inverters.

JP 2005-210006 JP-A-2005-159048

However, in the conventional technology, the ceramic substrate is caused by the heat stress generated when the semiconductor device is assembled or when the semiconductor device is energized, or by the thermal stress generated from the difference in thermal expansion coefficient between the ceramic substrate and the metal plate. There was a possibility that reliability such as cracking might deteriorate. Further, the heat radiating member is warped due to the difference in thermal expansion coefficient, and the close contact with the cooler is not good, which may cause a problem in heat dissipation.
In addition, in Patent Documents 1 and 2, since the ceramic substrate is not used, there is no concern that the ceramic substrate will break, and reliability can be obtained. However, since a resin sheet or resin adhesive is used, compared with the ceramic substrate. The thermal conductivity was less than 1/10, which was not sufficient.
Thus, there has been a demand for a semiconductor device that prevents cracking of the ceramic substrate and has more insulating heat while having insulation properties.

  As a result of intensive studies, the present inventor has solved the above problems by the following invention.

That is, the first invention is a semiconductor device comprising a heat radiating member for radiating heat, an electronic component including a semiconductor in a casing, a metal member for mounting the electronic component, and an electrode for energization, the metal member And a ceramic powder layer and a heat radiating member having a rough surface portion are sequentially in contact with each other. 2nd invention is providing the deaeration layer in the said ceramic powder layer. A third invention is that the metal member has an extended portion embedded in the ceramic powder layer. In a fourth invention, the deaeration layer is iron oxide containing iron as a main component. In a fifth aspect of the present invention, the heat dissipating member is a heat dissipating plate with a heat dissipating fin, a water-cooled heat dissipating member, wherein the rough surface portion is in contact with the ceramic powder layer.

Furthermore, the heat dissipation member is preferably aluminum, an aluminum alloy, copper, or a copper alloy. The heat radiating member may be at least one of aluminum or an aluminum alloy, and may have a heat radiating member formed on the surface by alumite treatment.

  The manufacturing of the semiconductor device of the present invention is carried out by depositing ceramic powder on a heat radiating member having a rough surface and pressing the ceramic powder from above with physical pressure to form a ceramic powder layer. A metal member and a metal member mounted on an electronic component are placed on the powder layer, and a bonding wire is joined between the electronic component and the electrode to enable energization. The electronic component is included in the space partitioned by the casing. What is necessary is just to fill resin and to install a lid | cover on the insulating resin. Some terminals are soldered directly to the circuit metal plate.

According to the present invention, a semiconductor device was obtained in which the heat dissipation was remarkably improved, the damage was not caused by the heat cycle, and the reliability was greatly improved.

An example of the present invention will be described with reference to FIG. The present invention is not limited to this form.
The outer case 3 that is a casing includes the electrode 2, the electronic component 6, the metal member 7, the ceramic powder layer 51, the deaeration layer 52, the bonding wire 8, the insulating resin 9, and the lid 10. The heat radiating member 4 is joined and arrange | positioned at the lower part. The electronic component 6, the electrode member 7, the ceramic powder layer 51, and the heat radiating member 4 are in contact with each other in this order.

As a casing, the outer case 3 is made of resin, has a substantially vertical wall on the heat radiation member 4 in four directions, and is joined with a resin adhesive. A screw stop may be used. Moreover, what filled the inorganic filler in resin is used suitably.
The exterior case 3 bonded to the heat radiating member 4 forms a space (not shown) that is a space in which the upper portion of the substantially rectangular parallelepiped shape is opened and can accommodate an electronic component (not shown). The accommodating portion accommodates the ceramic powder layer 51 for insulation, the metal member 7 in contact with the ceramic powder layer 51, the electronic component 6 mounted on the metal member 7, and the like. To the outside of the housing portion.

The heat dissipating member 4 is made of metal, and the metal is preferably aluminum, aluminum alloy, copper, or copper alloy. Further, the heat radiating member 4 is required to have a high thermal conductivity, and preferably has a thermal conductivity of 150 W / mK or more. This is because heat generated from a semiconductor or the like is transferred to the atmosphere or the like to dissipate it. Moreover, it is preferable that the said heat radiating member 4 is a heat sink, a heat sink with a heat sink, and a water-cooled heat radiator, and it is preferable that the side which adhere | attaches an exterior case is a plane at least. Furthermore, an insulating layer may be formed on the surface of the heat radiating member 4 in contact with the ceramic powder 5. (Not shown) Preferably, the heat dissipating member is aluminum or an aluminum alloy, and the insulating layer is alumina. Alumina is preferably anodized by anodizing aluminum.

  It is more preferable that the heat radiating member 4 has a rough surface portion that makes the surface rough. By making the surface rough, minute irregularities are formed. If the surface becomes rough, the surface area increases and the heat dissipation area expands, thereby greatly improving the heat conduction capability. In particular, by roughening the surface in contact with the deaeration layer or the ceramic powder layer 51, the powder of those layers is fitted into minute irregularities, the gap between the powders is buried, and the contact area is expanded. By reducing the gap, the efficiency of heat conduction is dramatically improved, and the insulation is improved because the gap is reduced. In the heat radiating member 4, the surface in contact with the deaeration layer or the ceramic powder layer 51 may be roughened, and the roughness corresponding to the particle size of the powder of these layers may be formed. Roughness of 10 μm to 1 mm in average roughness is sufficient. For roughening the surface, file polishing, blasting, or the like may be used. When measuring the thickness of the powder layer, a height measuring machine that can measure or measure the length with a photograph with a cross section enlarged about 10 times may be used.

  The metal member 7 preferably has high electrical conductivity and thermal conductivity such as aluminum and copper. Since the metal member 7 is used as a circuit for mounting a chip component such as a semiconductor element, the mounting location is preferably a plate shape. Furthermore, it is good to have the expansion part 71 which can be embed | buried under a ceramic powder layer. This is because the ceramic powder layer 51 increases the heat transfer efficiency. The extended portion 71 may be made of the same material as that of the metal member 7. For example, the extended portion 71 may have a square shape, a triangular shape, or an IC pin shape as shown in FIGS. 3 (d), (e), and (f). A thin metal rod may be cut and placed vertically on the surface to form a sword mountain. It is desirable that the tip of the extended portion 71 has an acute angle so as to reduce load resistance when embedded by being pushed into the ceramic powder layer 51. Since the extended portion 71 is embedded in the ceramic powder layer 51, the heat conduction is greatly improved. Further, it contributes to the stability of the form of the powder layer 5. When the ceramic powder layer 51 is formed by pressing, if a metal member is pressed through a pressing device, a hole having the same shape as the metal member 7 and the expanded portion 71 or the metal member 7 A recess having the same shape as the outer edge is formed to facilitate the installation of the metal member 7, and the ceramic powder layer 51 and the metal member 7 are in closer contact with each other, thereby improving the efficiency of heat conduction. Further, the position of the metal member 7 is stabilized and the installation is facilitated.

  The ceramic powder layer 51 is mainly composed of ceramic powder. It is preferable that the ceramic powder layer is filled with ceramic powder in the accommodating portion with a thickness of about 0.5 to 5 mm from the heat radiating member 4 without a gap, and pressure is applied so as to be flat. In this way, a ceramic powder layer can be formed. The average particle size of the ceramic powder 5 is preferably 50 μm or less, and more preferably 25 μm or less. With these thicknesses and particle diameters, an insulating property of 1 kV or more can be provided between the metal member 7 and the heat dissipation member 4. The thickness is more preferably 1 mm to 3 mm. The material of the ceramic powder 5 is preferably alumina, aluminum nitride, silicon nitride or the like, but aluminum nitride having a high thermal conductivity and excellent insulation is particularly preferable.

When a deaeration layer is sandwiched between the ceramic powder layer 51 and the heat dissipation member 4, the efficiency of heat conduction is further improved. By forming the deaeration layer, internal air and oxygen are consumed, so that the thermal expansion of the ceramic powder layer 51 can be suppressed, and the efficiency of heat conduction is improved.
Moreover, the surface deterioration of the metal member 7 by oxygen can be suppressed, and deterioration of heat conduction efficiency can be suppressed. The deaeration layer is formed of powder containing iron as a main component, so that the efficiency of heat conduction does not deteriorate. As the powder mainly composed of iron used for the deaeration layer, iron oxide obtained by firing goethite is preferable. Such iron oxide is commercially available, and a commercially available product may be used. Since iron also adsorbs nitrogen, it adsorbs not only oxygen but also nitrogen, and is more preferable. The particle size is preferably larger than the ceramic powder 5, and the average particle size D50 may be 50 μm to 1000 μm. This is to prevent mixing with the ceramic powder. Desirably, 200 micrometers or less are good.

  The heat is mainly generated by the electronic component 6, and this heat is transferred to the metal member 7, transferred to the ceramic powder layer 51 in contact with the metal member, and transferred to the heat dissipation member 4 in contact with the ceramic powder layer 51. In addition to being radiated to the atmosphere, which is the outside air, the heat is transferred to a further heat radiating device by water cooling or the like. In the ceramic powder layer 5 as described above, it is desirable that each member that conducts heat is in contact with a substantially flat surface having no undulations of several millimeters so that heat conduction is possible more efficiently. The larger one is desirable. Moreover, you may contact directly.

The electrode 2 communicates with the internal accommodating portion and the outside, and the outside is an external electrode. The electrode 2 may be attached to the exterior case, and is preferably electrically connected by the metal member 7 or the electronic component 6 and a bonding wire.

In addition, the ceramic powder 5, the metal member 7, the electronic component 6, the electrode 2, the bonding wire 8, and the like are accommodated in the accommodating portion of the outer case 3 and then sealed with an insulating resin 9, and the accommodating portion is covered with the lid 10. It is preferable that Note that the insulating resin 9 may be filled while pressing the metal member 7 so that the metal member 7 and the ceramic powder layer 51 are in close contact with each other. For pressing, a guide pin or a spring may be used from above.

An electronic circuit board in which electronic components or the like are previously mounted on a ceramic substrate by bonding or the like may be used. In this case, the electronic component 6 and the metal member 7 in FIG. 1 may be replaced with an electronic circuit board, and the electronic circuit board may be disposed on the ceramic powder layer 51. That is, the electronic circuit board, the ceramic powder layer 51, and the deaeration layer 52 are stacked in this order. It is desirable that the heat dissipation member has a rough surface portion. With such a configuration, the present invention can be applied to an electronic circuit board.

Thus, a semiconductor device comprising a heat dissipating member that dissipates heat from an electronic component or the like, and an electronic component containing a semiconductor in a housing, and a metal member and an electrode that energizes the electronic component, wherein the metal By sequentially contacting the member, ceramic powder layer, and heat dissipation member in this order, an unprecedented semiconductor device with high heat dissipation efficiency can be obtained, and the power for conducting a larger current. This is effective in electrical control using a transistor. In addition, if the semiconductor device is a similar semiconductor device including the metal member, the ceramic substrate, the ceramic powder layer, and the heat radiating member in this order, the electronic device Even in an electronic component having a larger number or a complicated structure that requires a substrate when mounting the component, it is possible to sufficiently dissipate heat, and a wider variety of excellent semiconductor devices can be obtained. Since ceramic powder is used for insulation, it also suppresses the decrease in thermal conductivity, the heat radiator does not warp due to the difference in thermal expansion coefficient, and when the semiconductor device is incorporated into an external device, , Failure can be suppressed.

Example 1
As shown in FIG. 2 (a), first, a cylindrical resin outer case 3 was prepared in which the upper and lower sides of a substantially rectangular parallelepiped in which the aluminum plate and the electrode 2 were previously assembled were opened as the heat radiating member 4. On the surface of the heat dissipating member 4, an uneven roughness having an average roughness of about 10 μm is formed in advance by polishing paper (surface rough portion 41). The aluminum plate material of the heat dissipating member 4 and the resin outer case 3 are joined with an epoxy-based thermoplastic resin.
As shown in FIG. 2 (b), an internal space formed by the heat sink and the outer case, that is, a storage part such as an electronic component, commercially available iron oxide powder is 0.1 mm above the heat sink in the storage part. I put it to become. Then, it pressed so that it might become substantially horizontal, and the deaeration layer was formed. Next, an aluminum nitride powder having a particle size of 10 μm or less was prepared as a ceramic powder 5 on the deaerated layer, and was placed in the housing portion so as to be 1 mm from the heat sink. After that, it was pressed so as to be substantially horizontal. In addition, when pressing, it pressed through the metal member 7, and the hole for the embedding part of the metal member 7 was previously formed in the ceramic powder layer.
As shown in FIG. 3D, the metal member 7 has a shape in which the extended portion has a square shape and is provided at two locations on the straight side. When viewed from above, a predetermined circuit is formed (not shown). In addition, when the metal member 7 was put on the heat radiating member 4 and the ceramic powder 5 and the dielectric strength voltage between them was measured, it was 1.2 kV or more (not shown).
As shown in FIG.2 (c), the metal member 7 was prepared and the semiconductor element and the chip component were joined previously by soldering on it. A metal member 7 to which the electronic component 6 was bonded was placed on the ceramic powder. Furthermore, the electrode or metal member 7 of the semiconductor chip and the electrode formed on the resin outer case 3 were electrically connected by an aluminum bonding wire 8. In addition, the bonding apparatus used for this wire bonding is designed so that it may not contact the said exterior case.
Further, an insulating epoxy resin 9 was placed thereon, a solid resin was further placed, and a lid 10 was placed on the outer case to complete the semiconductor device (FIG. 1).

  The semiconductor device was energized, and the heat dissipation and insulation of the semiconductor device caused by the heat generated by the electronic component 6 were evaluated. For evaluation of heat dissipation, the temperature of the electronic component 6 was measured. The insulation was evaluated by measuring the presence or absence of a signal because the signal immediately cuts off from the device when dielectric breakdown occurs. As a result, the temperature launched a signal without exceeding 95 ° C., and the electronic components operated in good condition. There was no warping. That is, it was in a good heat dissipation state and could maintain insulation. Moreover, the heat cycle test was implemented. Room temperature + 125 ° C. for 30 minutes, room temperature for 10 minutes, −40 ° C. for 30 minutes, and room temperature for 10 minutes were defined as one cycle. As a result, there was no dielectric breakdown even after 1000 cycles.

Schematic diagram of a semiconductor device according to the present invention. Intermediate body schematic diagram of semiconductor device according to Example 1 of the present invention Schematic representation of the form of the metal member of the present invention

Explanation of symbols

1: Semiconductor device 2: Electrode 3: Exterior case 4: Heat radiation member 41: Surface rough portion 51 of the heat radiation member: Ceramic powder layer 52: Deaeration layer 6: Electronic component (semiconductor chip or the like)
7: Metal member 71: Expansion part 8: Bonding wire 9: Insulating resin 10: Lid 11: Ceramic substrate (a): Intermediate according to example (b): Intermediate according to example (c): Example Such intermediates

Claims (5)

A semiconductor device comprising a heat dissipation member that dissipates heat, an electronic component including a semiconductor in a housing, a metal member that mounts the electronic component, and an electrode that is energized, the metal member, a ceramic powder layer, A semiconductor device comprising: a heat dissipation member having a rough surface portion, which are sequentially in contact with each other. The semiconductor device according to claim 1, wherein the ceramic powder layer includes a deaeration layer. The semiconductor device according to claim 1, wherein the metal member has an extended portion embedded in a ceramic powder layer. The semiconductor device according to claim 1, wherein the deaeration layer is made of iron oxide containing iron as a main component. 5. The semiconductor device according to claim 1, wherein the heat radiating member is a heat radiating plate with a heat radiating fin and a water-cooled heat radiating member, the surface rough portion being in contact with the ceramic powder layer.

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