JPH06310628A - Hybrid integrated circuit - Google Patents

Abstract

PURPOSE:To improve heat radiation characteristics and reliability during a heat cycle by fixing switching elements on a heat sink. CONSTITUTION:This circuit is formed by prepaing a conductive route 3 on a metallic substrate 1 with an insulation layer 2 interposed in between and forming an invertor circuit thereon, and a switching means constituting the invertor circuit on a source side or a sink side has a plurality of switching elements 5 connected in parallel respectively. Then, each of the switching elements 5 constituting the switching means is respectively fixed on an individual heat sink 4. The heat sinks 4, whose surface area is divided into a plurality of areas by an insulation resin 3B such as a solder resist, etc., are fixed by respective divided areas, and further they are provided with covering resins 6 on their upper surfaces in order to cover/protect the elements 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid integrated circuit, and more particularly to a mounting structure for mounting a plurality of power semiconductor elements on a heat sink.

[0002]

2. Description of the Related Art A hybrid integrated circuit having a general conventional structure on which a power semiconductor device is mounted will be described below (see FIG. 5). For example, an inverter circuit as shown in FIG.
When it is formed on the substrate (10), the insulating substrate (1) made of ceramics or aluminum whose surface is anodized.
Forming a conductive path (11) for the inverter circuit on
A heat sink (13) to which a switching element (12) necessary for operating the inverter circuit is fixed is fixed to a desired position of the conductive path (11), and an epoxy-based sealing resin ( 14) is applied,
The structure was such that the switching element (12) was covered and protected with the sealing resin (14).

A groove (15) is formed on the upper surface of the heat sink (13) to which the power transistor (12) is fixed, and the sealing resin layer (14) is attached to the heat sink (1).
3) When applied on top, a part of the sealing resin layer (14) is filled in the groove (15) to improve the adhesive strength. In the hybrid integrated circuit having the conventional structure as described above, by providing the groove (15) in the heat sink (13), the heat sealing resin layer (14) and the heat sink (1) are formed.
It is possible to prevent peeling of the interface with 3). As a result, the power semiconductor element (12) and the heat sink (13)
The reliability was improved by suppressing the solder oxidation of the solder layer that adheres to

The technique as described above is disclosed in JP-A-60-6555.
No. 3 publication. A similar technique for covering and protecting a power semiconductor element such as a power transistor with a sealing resin is disclosed in JP-A-58-40848 and JP-A-56-4.
3166 and Japanese Utility Model Laid-Open No. 59-26253.

[0005]

The above-mentioned conventional hybrid integrated circuit has a structure in which one power semiconductor element is fixed on one heat sink, and therefore, for example, an inverter circuit as shown in FIG. Effective when implemented on top. However, when the amount of current flowing through the inverter circuit is a large current of about 50 to 300 A,
As shown in FIG. 7, a plurality of switching means (switching elements) of the inverter circuit are connected in parallel. When each switching element connected in parallel is mounted on one heat sink (20) as shown in FIG. 8 and covered with a sealing resin (21) such as epoxy, the heat sink (20)
Since the contact interface distance between the epoxy resin (21) and the epoxy resin (21) becomes long, cracks occur at the interface between the heat sink (20) and the epoxy resin (21) during the heat cycle, and the switching element (22) and the heat sink (20) are fixed to each other. The solder layer is oxidized. There is a problem that the thermal resistance of the solder layer is increased by the oxidization and the switching element is destroyed along with the change with time.

Further, in the structure as shown in FIG. 8, since a plurality of switching elements are fixed on the heat sink, when a void is generated in one of the solder layers fixing the heat sink and each switching element, There was a problem that it was treated as a defective product and the yield decreased. When the collectors or source electrodes of the switching elements as shown in FIG. 7 are common and the pads formed on the substrate are commonly used, each switching element is individually connected in addition to that shown in FIG. It is conceivable to fix the heat sink on the heat sink and solder the heat sink on the pad. At this time, when the solder connecting the heat sinks and the pads melts, the adjacent solders bond with each other due to their wettability, and as a result, the heat sinks are closely arranged. Even if the heat sinks are closely arranged, no electrical problem occurs.

However, when the heat sinks are closely arranged, even if the coating resin is applied only to one heat sink, it is continuously applied to the adjacent heat sinks due to mechanical problems. When the coating resin is continuously applied to the adjacent heat sink, the above-mentioned heat cycle problem occurs. This invention has been made in view of the above-mentioned problems, and an object of this invention is to
Improving reliability by heat cycle of a hybrid integrated circuit having a structure in which a plurality of heat sinks to which a power semiconductor element is fixed are fixed to an electrically commonly used pad and a coating resin is applied to the heat sinks. That is.

[0008]

[Means for Solving the Problems]
To achieve the object, a first hybrid integrated circuit according to the present invention is a hybrid integrated circuit in which a plurality of heat sinks to which power semiconductor elements are fixed are fixed on a pad region of a conductive path of a desired shape formed on an insulating substrate. The circuit is characterized in that the pad region is divided into a plurality of regions by an insulating resin film such as a solder resist, and a heat sink is fixed to each of the divided regions so as to be adjacent thereto.

A second hybrid integrated circuit according to the present invention is a hybrid integrated circuit in which an inverter circuit is formed on a conductive path formed on a metal substrate via an insulating layer.
A plurality of switching elements are connected in parallel in the switching means on the source side or the sink side that constitutes the inverter circuit, and each switching element that constitutes the switching means is fixed on an individual heat sink. It is characterized in that it is fixed to each of the divided areas divided into a plurality of areas by an insulating resin such as a solder resist, and a coating resin for covering and protecting the switching element is provided on the upper surface thereof.

[0010]

In the hybrid integrated circuit configured as described above, the pad region to which a plurality of heat sinks are fixed is divided into a plurality of regions by an insulating resin film such as solder resist, and the heat sinks are fixed to each of the divided regions. By doing so, when fixing each heat sink with solder, it is possible to prevent the molten solder from being coupled with the adjacent molten solder because the molten solder is blocked by the resist ink even if the solder melts.

As a result, the adjacent heat sinks do not come into close contact with each other, a space of a certain distance can be surely secured, and the coating resin can be applied only on one heat sink.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A hybrid integrated circuit of the present invention will be described below based on the embodiments shown in FIGS. As shown in FIGS. 1 and 2, the hybrid integrated circuit of the present invention comprises an insulating substrate (1),
Conductive path (3) of desired shape formed on this substrate (1)
A plurality of heat sinks (4) fixed on the pad (3A) region at a predetermined position of the conductive path (3), an insulating resin film (3B) dividing the pad (3A) region, and each heat sink ( 4) A power semiconductor element (5) fixed onto the power semiconductor element (5) and a coating resin (6) for coating and protecting the power semiconductor element (5).

As the insulating substrate (1), a ceramic or a metal substrate subjected to an insulating treatment is used. In this embodiment, considering the heat radiation characteristics and workability, it is about 2 to 5 mm.
Thick aluminum or copper substrates are used. The substrate (1) is formed in a rectangular shape with a predetermined size and divided and pressed into a desired size before or after the hybrid integrated circuit is completed. When an aluminum substrate is used, the surface of the aluminum substrate may be covered with a thin film of aluminum oxide. When a copper substrate is used, the surface of the copper substrate is plated with nickel or chromium to protect the surface.

On one main surface of the aluminum substrate (1),
A clad material composed of a thermosetting insulating resin having adhesiveness such as epoxy or polyimide resin and a copper foil having a thickness of about 35 to 105 μm is hot-pressed at a temperature of 150 to 180 ° C. and a pressure of 50 to 100 kg per 1 cm 2. The thermosetting insulating resin becomes an insulating layer (2) by hot pressing the clad material onto the substrate (1), and the copper foil on the insulating layer (2) is photo-etched to form a conductive path having a desired shape. (3) is formed.

Conductive paths (3) formed on the substrate (1)
For example, the inverter circuit shown in FIG. 7 is formed.
As shown in FIG. 3, screen printing is performed at a predetermined position of the conductive path (3), that is, on a pad (3A) region for fixing the heat sink (4) to which the switching means (switching element) of the inverter circuit is fixed. The solder paste printed by is attached by screen printing or the like to form a solder layer (8). As shown in FIG. 3, the solder layer (8) is formed in a plurality of places at predetermined intervals in the area of the pad (3A). The pad (3A) region is formed in a cross shape with an insulating resin film (3) such as a solder resist.
It is divided into a plurality according to B). Solder layer described above (8)
Will be arranged in a divided region divided by the resin film (3B), and each adjacent solder layer (8) will be divided by the resin film (3B). The width of the resin film (3B) is about 0.5 to 1 mm in consideration of thermal resistance. Further, in this embodiment, the resin film (3B) is formed in a cross shape, but the shape of the resin film (3B) is not limited to this.

By the way, the first power supply line (for example, V _CC line), the second power supply line (for example, earth line) and the output line for supplying the current of the inverter circuit shown in FIG. 7 correspond to a large current of about 50 to 300 A. The thickness of the copper foil is about 35 to 105 μ because it is necessary to make it possible. If the thickness is not enough, about 1 on the copper foil
It is also conceivable to fix a copper plate having a wall thickness of about 5 mm.

In the hybrid integrated circuit of the present invention, in order to be able to handle a current of about 100 A or more, each switching element is connected in parallel as shown in FIG.
The switching elements connected in parallel are soldered to each heat sink (4) via a solder (9) made of a metal or an alloy material such as copper, an invar-copper-invar alloy, or DBC.

As shown in FIG. 4, each heat sink (4) to which the switching element (5) is fixed is placed on each solder layer (8) provided on the pad (3A) area, and is subjected to the solder reflow process. The solder layer (8) is melted and the pad (3
Each heat sink (4) is soldered and fixed onto A). When each solder layer (8) is melted, the pad (3A) region is divided by the insulating resin film (3B), so each solder layer (8)
The molten solder of (3) will be dammed by the resin film (3B), and adjacent molten solders will not be joined together. Therefore, it is possible to prevent the risk that the heat sinks (4) are closely attached to the pads (3A) by soldering.

Each heat sink (4) on the pad (3A)
After fixing, the power switching element (5) fixed on each heat sink (4) is covered and protected by the epoxy-based covering resin (6). When the coating resin (6) is applied on each heat sink (4), each heat sink (4) is surely applied on one heat sink (4) because a predetermined interval is secured as described above. Is possible. Therefore, even when the resin (6) is applied to one heat sink (4), it is possible to prevent the resin (6) from being continuously applied to the adjacent heat sinks (4), and the heat can be prevented. There is no risk of cracks occurring in the interface region between the resin (6) and the heat sink (4) due to the cycle. The resin (6) is placed on the heat sink (4).
A groove having an inverse taper surface is provided to improve the adhesive force with the.

By the way, the switching element (5) fixed on each heat sink (4) has a conductive path (3) extending around the heat sink (4) before the coating resin (6) is applied. ) And aluminum wire bonding connection. In such a hybrid integrated circuit of the present invention,
One pad (3A) area is divided by the resin film (3B),
By fixing and mounting the respective heat sinks (4) to which the switching elements (5) connected in parallel are fixedly mounted on the respective divided regions, the respective heat sinks (4) can be fixed onto the pad without closely contacting each other. The coating resin can be reliably applied to each heat sink (4). As a result, even in a large current type hybrid integrated circuit in which the switching elements (5) are connected in parallel, the reliability in the heat cycle can be improved.

[0021]

As described in detail above, according to the present invention,
By dividing one pad area to which the heat sink is fixed into a plurality of areas with an insulating resin film such as a solder resist and fixing each heat sink to each of the divided areas,
When the heat sinks are fixed by soldering, even if the solder melts, the resist ink dams the melted solder, so that the heat sink can be prevented from being coupled with the adjacent melted solder.

Therefore, the adjacent heat sinks do not come into close contact with each other, a space of a certain distance can be surely secured, and the coating resin can be surely applied onto only one heat sink. As a result, the reliability due to the heat cycle can be improved even in a large current type hybrid integrated circuit.

[Brief description of drawings]

FIG. 1 is a sectional view showing a hybrid integrated circuit of the present invention.

FIG. 2 is a plan view showing a hybrid integrated circuit of the present invention.

FIG. 3 is a plan view and a sectional view of a main part for explaining the present invention.

FIG. 4 is a plan view and a cross-sectional view of a main part for explaining the present invention.

FIG. 5 is a cross-sectional view showing a conventional hybrid integrated circuit.

FIG. 6 is a circuit diagram of an inverter circuit.

FIG. 7 is a circuit diagram of an inverter circuit.

FIG. 8 is a cross-sectional view showing a conventional hybrid integrated circuit.

[Explanation of symbols]

 (1) Insulating substrate (2) Insulating layer (3) Conductive path (3A) Pad (3B) Insulating resin film (4) Heat sink (5) Switching element (power semiconductor element) (6) Coating resin

Claims (2)

[Claims] 1. A hybrid integrated circuit in which a plurality of heat sinks having power semiconductor elements are fixed on a pad region of a conductive path of a desired shape formed on an insulating substrate, wherein the pad region is formed of a solder resist or the like. A hybrid integrated circuit characterized by being divided into a plurality of regions by an insulating resin film, and the heat sinks being fixed to each of the divided regions so as to be adjacent to each other. 2. A hybrid integrated circuit in which an inverter circuit is formed on a conductive path formed on a metal substrate via an insulating layer, wherein a switching means on a source side or a sink side constituting the inverter circuit is composed of a plurality of switching means. Switching elements are connected in parallel, each switching element constituting the switching means is fixed on an individual heat sink, and the surface area of the heat sink is divided into a plurality of areas by an insulating resin such as solder resist. A hybrid integrated circuit characterized in that it is fixed to each of the divided regions, and a coating resin for coating and protecting the switching element is provided on the upper surface thereof.