JPH0131689B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides wiring to a semiconductor element fixed on a substrate by direct connection between a wiring conductor provided on the substrate and an electrode of a semiconductor element chip, and connection by a connecting conductor. Concerning complex integrated circuits.

The wiring conductors of a composite integrated circuit are formed, for example, by printing and firing a conductor on a ceramic substrate, or by etching a metal foil insulated and bonded to a metal substrate. Figure 1 shows an example of the latter, with a metal substrate 1 having good thermal conductivity such as aluminum.
A copper foil 3 is adhered thereon via an insulating adhesive layer 2, and a plating layer 4 of, for example, gold or nickel, which allows wire bonding of aluminum wires, is provided on the copper foil 3, and then etched. A desired wiring pattern is formed by a method. Alternatively, after etching the copper foil 3 into a desired pattern, partial plating may be applied only to the areas necessary for connection. Semiconductor chip 6 is placed on plating layer 4 via solder layer 5.
is fixed, and the aluminum electrode on its upper surface and the plating layer 41 of another wiring conductor are connected by wire bonding using the ultrasonic vibration method of the aluminum connecting conductor 7. If the semiconductor element chip 6 is one that dissipates a large amount of heat, such as a power transistor chip, a metal heat radiator 8 is sandwiched over the plating layer 4, and the chips 6 are fixed using the solder layer 5. Similarly, by wire bonding the aluminum wire 7, the exposed plating layer 41 of the wiring conductor is connected to the aluminum electrode of the chip 6.

However, in such a composite integrated circuit, the aluminum wire 7 must be wire-bonded to the aluminum electrode of the semiconductor element chip 6 and the Au or Ni plating layer 41 on the copper foil 3.
Since the materials and surface conditions of both are different, it is troublesome to adjust the bonding conditions for each in order to perform optimal bonding. It is technically difficult to apply Al plating on the copper foil 3 to make the same material. Furthermore, when the heat sink 8 is used, a step is created between the electrode surface on the chip 6 and the surface of the plating layer 41 on the wiring conductor, so the aluminum wire 7 comes into contact with the side surface of the heat sink 8, causing a short circuit. There is a risk that this may occur, and the reliability is not sufficient.

It is an object of the present invention to eliminate such drawbacks and provide a highly reliable composite integrated circuit that can be easily connected by conductive wires.

This object is a composite integrated circuit in which an aluminum electrode of a semiconductor element chip is connected by an aluminum wire to the upper surface of an auxiliary body fixed on a wiring conductor provided on a substrate, the auxiliary body being Made of aluminum or aluminum alloy,
This is achieved by plating the side fixed onto the wiring conductor with copper that is thinner than the thickness of the aluminum or aluminum alloy.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, parts common to those in FIG. 1 are given the same reference numerals. No plating layer 4 is provided on the copper foil 3 forming the wiring pattern on the substrate 1, and the semiconductor element chip 6 is directly fixed to the copper foil 3 via the solder layer 5. An auxiliary body 9 is brazed with a solder layer 5 at the location of the wiring conductor to be connected to the aluminum electrode on the upper part of the chip 6. The auxiliary body 9 is made of the same kind of aluminum or aluminum alloy as the material of the electrodes of the chip 6, but has a copper plating layer 11 on one side of an aluminum plate 10, as shown in FIG. Since the copper plating layer 11 is formed by plating, it is thinner than the thickness of the aluminum plate 10, but the copper foil 3 is easily formed on the side of the plating layer 11.
It can be soldered. Next, aluminum wire 7
The aluminum electrode on the top surface of the chip 6 and the aluminum surface on the top side of the auxiliary body 9 are connected by wire bonding using ultrasonic vibration. Since both connections are made of aluminum, bonding can be easily performed under the same conditions. When a semiconductor element dissipates a large amount of heat and is fixed to a wiring conductor via a heat sink 8, a layer with a thickness comparable to the thickness of the heat sink 8 is placed on the wiring conductor connected to the upper electrode of the element chip 6. The auxiliary body 91 is brazed. Thereby, the connection by the aluminum wire 7 can be made to the same type of material in approximately the same horizontal plane. Therefore, the length of the aluminum wire 7 is the shortest, and there is no possibility that the aluminum wire will touch the side surface of the heat sink 8.
No short circuit occurs.

According to the present invention, there is no need to provide an expensive plating layer such as gold plating on the wiring conductor, and since an auxiliary body is provided only at the connection location, the minimum amount of material is required. Furthermore, since the auxiliary body is mainly made of aluminum, it is light and the solder does not adhere to the side surfaces of the aluminum plate 10, so that solder does not creep up or flux adheres to the bonding surface, and bonding can be performed accurately. The present invention is not limited to the above-described composite integrated circuit on a metal substrate, but can also be applied to a ceramic substrate in which wiring is provided using printed and fired conductors.

As described above, the present invention uses an aluminum electrode of a semiconductor element chip fixed on a substrate of a composite integrated circuit and an auxiliary body of aluminum or aluminum alloy, and connects similar materials with an aluminum wire. Since the conductors can be fixed under the same conditions, connection work is easy and reliable.
Further, since it is possible to use an auxiliary body having such a thickness that connection with the element using the heat sink can be made in the same horizontal plane, short circuits can be prevented, and the effects obtained are extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an example of a conventional composite integrated circuit, FIG. 2 is a sectional view of a main part of an embodiment of the present invention,
FIG. 3 is a sectional view of one embodiment of the auxiliary body. 1... Metal substrate, 2... Insulating adhesive layer, 3...
...Copper foil, 5...Solder layer, 6...Semiconductor element chip, 7...Connection conductor, 9, 91...Auxiliary body, 10
...Aluminum plate, 11...Copper plating layer.

Claims (1)

[Claims] 1 A composite integrated circuit in which an aluminum electrode of a semiconductor element chip is connected by an aluminum wire to the upper surface of an auxiliary body fixed on a wiring conductor provided on a substrate, and the auxiliary body is made of aluminum or aluminum. A composite integrated circuit made of an alloy, characterized in that the side fixed onto the wiring conductor is plated with copper which is thinner than the thickness of the aluminum or aluminum alloy.