JPH0450744B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a hybrid integrated circuit, and particularly to improvements in a hybrid integrated circuit using a metal substrate.

(b) Prior Art As shown in FIG. 3, a conventional hybrid integrated circuit is manufactured by printing and baking a paste containing noble metal powder on a ceramic substrate 10 to form a thick film 11, which connects a semiconductor chip and a circuit board. A dam 13 made of an insulating material is provided to prevent solder from flowing out during the process, and after covering the thick film wiring with solder plating 12, the surface of the semiconductor chip 14, on which solder bumps have been formed on the wiring terminals in advance, is placed in the direction of the substrate 10. board 10
was connected to.

A technique similar to that described above is described in Japanese Patent Application Laid-Open No. 59-106140.

However, the above-mentioned hybrid integrated circuit uses a ceramic substrate, so its mechanical strength is weak.
It had the drawbacks of being expensive and having poor heat dissipation.

Therefore, as shown in FIG. 3, an aluminum substrate 20 with good thermal conductivity was used, an aluminum oxide film 21 was formed on the surface of the substrate 20, and a conductive path 23 was further formed on the upper surface with an insulating resin 22 interposed therebetween. Thereafter, the semiconductor element 24 was face-down connected on the conductive path 23 to solve the above-mentioned drawback.
However, the thermal expansion coefficient α of the aluminum substrate 20 mentioned above is 24×10 ^-6 /°C, whereas the thermal expansion coefficient α of the semiconductor element 24 is 2.4×10 ^-6 /°C, which is a significant difference between the two. There was a fear that cracks would occur in the solder connecting the semiconductor element 24 and the aluminum substrate 20 due to temperature cycling.

In order to eliminate the above-mentioned drawbacks, we invented a metal substrate 30 having a three-layer structure of a copper plate 31, an invar 32, and a copper plate 31, as shown in FIG. According to this three-layer structure substrate 30, the thermal expansion coefficient α of the metal substrate 30 can be significantly reduced, and the thermal expansion coefficient α of the semiconductor element can be significantly reduced.
This has the advantage that cracks do not occur in the solder that connects the metal substrate and the semiconductor element.

(C) Problems to be Solved by the Invention However, when a resin layer and a copper foil are directly pasted on the copper plate of the above-mentioned three-layer structure board of copper plate, invar, and copper plate, the surface of the copper plate is extremely damaged by the rolling process. Because it is formed densely and smoothly, when the metal substrate is heated to around 320℃ during the solder reflow process, gas is generated from the insulating resin layer, and the gas causes the copper plate, that is, the metal substrate and the resin layer to separate. This had the disadvantage of pushing up the copper foil.

(d) Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and as shown in FIG. This problem is solved by providing an aluminized layer 4 thereon and providing an aluminum oxide film 5 on the aluminized layer 4 by anodic oxidation.

(e) Effect By providing the aluminized layer 4 and the aluminum oxide film 5 on the metal substrate 1 having the three-layer structure of the copper plate 2, the invar 3, and the copper plate 2 in this way, the surface of the aluminum oxide film 5 is formed to be porous. Therefore, adhesion with the resin layer 6 is improved, and peeling of the resin layer 6 can be prevented.

(f) Examples The present invention will be explained in detail below based on the examples shown in FIG.

The metal substrate 1 is made of copper plate 2, invar 3, and copper plate 2, each with a lamination ratio of 1:3:1 of 10 to 30 tons/
Cladding treatment is performed using rollers with a pressure of cm ² , and after stretching in a rolling process to a predetermined thickness, it is punched into a predetermined size using a press. The board 1
The surface is plated with aluminum by electrolytic plating or the like to form an aluminized layer 4, and the surface is further anodized to form an aluminum oxide film 5. Invar 3 is 36% nickel and 64% iron.
It is an alloy with a coefficient of thermal expansion α of 1.5×10 ^-6 /℃
It is.

After forming an aluminized layer 4 and an aluminum oxide film 5 on a metal substrate 1, an insulating resin layer 6 and a copper foil serving as a conductive path 7 are adhered onto the surface thereof.
The insulating resin layer 4 is made of epoxy resin or the like. Next, a conductive path 7 is formed by etching the copper foil into a predetermined pattern, and Au is deposited on the conductive path 7 at a position corresponding to the bump electrode of the semiconductor element 8, and solder is dipped in the solder reflow process. Metal substrate 1
is heated to around 320°C, and the semiconductor element 8 is connected face-down onto the metal substrate 1.

According to the present invention, by providing the aluminum oxide film 5 on the metal substrate 1 having the three-layer structure of the copper plate 2, the invar 3, and the copper plate 2 via the aluminized layer, the surface of the aluminum oxide film 5 is made porous. Since the insulating resin layer 6 is made of a solid material, the insulating resin layer 6 penetrates into the holes and has good adhesion, and has the advantage that the resin layer 6 does not peel off as in the conventional case even if the substrate 1 is heated to around 320°C.

(G) Effects of the Invention As described above, according to the present invention, by providing an aluminum oxide film on a metal substrate having a three-layer structure of a copper plate, an invar plate, and a copper plate via an aluminized layer, the surface of the aluminum oxide film can be coated. Since the resin penetrates into the holes formed, the adhesion between the aluminum oxide film and the resin layer becomes strong, and even if gas is generated from the resin layer when the board is heated during the solder reflow process, the resin will not be released, which was previously the case. Peeling of layers can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIGS. 2 to 4 are sectional views showing a conventional example. 1...Metal board, 2...Copper plate, 3...Invar

Claims (1)

[Claims] 1. A metal substrate with a three-layer structure in which both sides are made of copper plates and invar is provided between them, an aluminized layer provided on the metal substrate, an aluminum oxide film provided on the aluminized layer, and the oxidized 1. A hybrid integrated circuit comprising a conductive path of a desired shape provided on an aluminum film via an insulating resin, and a plurality of semiconductor elements provided on the conductive path.