JPH0529491A - Circuit board for mounting semiconductor - Google Patents

Abstract

PURPOSE:To provide a circuit board for mounting semiconductors having high joining reliability WITH silicon chips. CONSTITUTION:Since this circuit board for mounting semiconductors is constituted by forming a conductive layer composed of a plurality of different kinds of metallic layers 3 on a metallic substrate 1 with an insulating layer 2 in between and the layer 3 contains a molybdenum layer 6, a wiring circuit having a coefficient of thermal expansion which is close to that of silicon chips can be formed. In addition, since the circuit board 1 has a high thermal shock resistance, the cracking of solder fixing silicon chips can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor-mounted circuit board used in electric equipment, communication equipment, automobiles, etc.
In particular, the present invention relates to a semiconductor-mounting circuit board having a high bonding reliability with a silicon chip.

[0002]

2. Description of the Related Art Conventionally, as a circuit board for mounting semiconductors for high density mounting of electric equipment, communication equipment, automobiles, etc., on a laminate formed by sequentially laminating aluminum-copper clad foil on a metal substrate via an insulating layer. A semiconductor-mounting circuit board in which a wiring circuit is formed by etching an aluminum-copper clad foil is used (Japanese Patent Publication No. 1-15153).

[0003]

However, as high-density mounting progresses, the heat generated in the silicon chip and other elements during use is increased in applications such as electric equipment, consumer equipment such as automobiles, etc. where environmental conditions are severe. The temperature of the circuit board rises due to heat transfer from the outside or outside. Therefore, there is a problem that the solder fixing the silicon chip is cracked due to thermal strain due to the difference in coefficient of thermal expansion between the silicon chip and the circuit foil and thermal shock due to turning the power supply on and off.

The present invention has been made in view of the above problems, and suppresses thermal strain due to a difference in thermal expansion coefficient between a silicon chip and a circuit foil to prevent solder cracking and high reliability of bonding with a silicon chip. It is an object of the present invention to provide a semiconductor mounting circuit board having properties.

[0005]

That is, a semiconductor-mounting circuit board of the present invention is a semiconductor-mounting board in which a conductive layer composed of a plurality of dissimilar metal layers is laminated on a metal substrate via an insulating layer. A circuit board for mounting semiconductor, comprising a molybdenum layer inside a conductive layer.

[0006]

In the semiconductor mounting circuit board of the present invention, the conductive layer forming the wiring circuit is formed of a plurality of different metal layers, and the molybdenum layer having a thermal expansion coefficient close to that of silicon is interposed therein. Since it is possible to form a wiring circuit having a coefficient of thermal expansion close to that of a silicon chip, thermal distortion does not occur even when the ambient temperature rises, and it is possible to prevent the occurrence of solder cracks that fix the silicon chip.

The present invention will be described in detail below with reference to the drawings. 1 and 2 are cross-sectional views of a laminate used for a substrate of a semiconductor mounting circuit board of the present invention. FIG. 3 shows an embodiment, and FIG. 4 shows a prior art. In FIG. 1, an aluminum foil 4 is laminated on a metal substrate 1 via an insulating layer 2 with an aluminum foil 4 as an upper surface of a conductive foil 3 made of a plurality of metal foils composed of aluminum foil, molybdenum foil, and clad foil of copper foil. Here, an example of the molybdenum layer laminated between copper foils is shown. FIG. 2 shows a cross-sectional view of the circuit board with the copper foil 5 of the clad foil 3 of the aluminum foil, the molybdenum foil, and the copper foil to be laminated on the insulating layer 2 as the upper surface. The conductive layer 3 is formed. These dissimilar metal layers are composed of at least two kinds, and a part of this metal layer does not necessarily have to be a foil, and may be, for example, a metal layer formed by plating or vapor deposition. Further, FIG. 3 is a cross-sectional view of a semiconductor mounting circuit in which a semiconductor is mounted on the semiconductor mounting circuit board of the present invention.

As the base metal substrate 1 used in the semiconductor-mounting circuit board of the present invention, aluminum and aluminum alloys having good conductivity, copper and copper alloys, iron, stainless steel and the like can be used. The thickness of the base metal substrate 1 is not particularly limited, but 0.5 mm to 3.0 mm is generally used.

As the insulating layer 2 used in the present invention, various ceramics, a polymer resin insulating layer containing an inorganic filler, a polymer resin layer containing a glass fiber and a heat resistant polymer resin insulating layer are used. Be done. The thickness of the insulating layer 2 is not particularly limited as long as it does not cause insulation failure, and 20 μm or more is generally used. As the inorganic powder used for the insulating layer 2, alumina, silica, beryllia,
Boron nitride, magnesia, silicon nitride, aluminum nitride, silicon carbide and the like are used, and as the polymer resin, epoxy resin, phenol resin, polyimide resin and various engineered plastics can be used.

The aluminum material of the aluminum-molybdenum-copper clad foil 3 used in the present invention is as follows:
Pure aluminum and aluminum alloys may be used. The aluminum, molybdenum, and copper may be joined by rolling or plating. Also,
In the case of the plating method, zinc, tin, nickel or the like may be plated between aluminum and copper in order to increase the bonding strength between aluminum and copper.

The thickness of the aluminum-molybdenum-copper clad foil 3 of the present invention is not specified, but
For example, 35 μm to 1,000 μm is preferable for high current use, and 9 μm to 70 μm is preferable for small current for control.

The molybdenum layer of aluminum-molybdenum-copper clad foil 3 used in the present invention may be laminated between aluminum and copper, between aluminum-copper clad foil and copper, or between aluminum and aluminum-copper clad. It doesn't matter between it and the foil. Moreover, the aluminum-molybdenum-copper clad foil and the insulating layer may be bonded to each other by an aluminum surface or a copper surface.

[0013]

Embodiments of the present invention will be specifically described with reference to the drawings.

Example 1 In FIG. 3, an insulating adhesive is applied to an aluminum substrate 1 having a thickness of 3.0 mm to a thickness of 100 μm, and aluminum 40 μm-copper 150 μm-molybdenum 10 μm.
FIG. 4 is a cross-sectional view of a semiconductor-mounted circuit in which a semiconductor or the like is mounted using a circuit board in which the clad foil 3 of m-copper 150 μm is laminated with the aluminum foil surface as an upper surface. A resist is applied to the circuit board by a screen printing method, and both of the aluminum-molybdenum-copper clad foil 3 are etched with ferric chloride or the like that can be etched to form a wiring circuit. After removing the resist, the resist is again applied to the portion where the aluminum pad is required, and the unnecessary aluminum portion is removed by using an etching solution such as alkali etching that selectively dissolves aluminum to expose the copper foil portion. After removing the resist, a semiconductor or a chip resistance element is mounted on the copper circuit 5 via solder 9, and then the semiconductor 8 and the aluminum circuit 4 are connected to the aluminum lead wire 7.
By the ultrasonic vibration method.

The semiconductor mounting substrate thus manufactured is
Using a heat shock tester (Tabay) "TSR-63", a thermal shock test was conducted under the conditions of -50 ° C * 30min = + 150 ° C * 30min. If the solder cracks are caused by thermal shock, the electrical resistance increases. FIG. 5 shows the result of examining the electric resistance between this silicon chip and the conductive foil bonded to the chip. Almost no increase in resistance value was observed after 1200 thermal shock tests.

Comparative Example 1 FIG. 4 shows that an insulating adhesive is applied to an aluminum substrate 1 having a thickness of 3.0 mm to a thickness of 100 μm and aluminum 40 μm-copper 300 μm aluminum-
A circuit is formed by laminating copper clad foils (4, 5) with an aluminum surface as an upper surface, and a semiconductor is mounted by forming a circuit by the same method as in the first embodiment. FIG. 5 shows the result of a thermal shock test conducted on the semiconductor mounting substrate in the same manner as in Example 1.

[0017]

By using the aluminum-molybdenum-copper clad foil, it has become possible to manufacture a circuit board for mounting semiconductors having a high bonding reliability with a silicon chip.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an aluminum-molybdenum-copper clad foil with an aluminum foil as an upper surface in a semiconductor-mounting circuit board of the present invention.

FIG. 2 is a cross-sectional view of a semiconductor-mounting circuit board according to the present invention with a copper foil of an aluminum-molybdenum-copper clad foil as an upper surface.

FIG. 3 is a cross-sectional view of a semiconductor mounting circuit in which a semiconductor or the like is mounted on the semiconductor mounting circuit board of the present invention.

FIG. 4 is a cross-sectional view of a semiconductor mounting circuit in which a semiconductor or the like is mounted on a semiconductor mounting circuit board used as a comparative example of the present invention.

FIG. 5 is a graph showing a change with time in electric resistance between a silicon chip and a bonded conductive foil in a thermal shock test.

[Explanation of symbols]

 1. Base metal substrate 2. Insulation layer 3. Aluminum-molybdenum-copper clad foil 4. Aluminum foil 5. Copper foil 6. Molybdenum foil 7. Lead wire 8. Silicon chip 9. solder

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 3/38 C 7011-4E

Claims (1)

Claim: What is claimed is: 1. A semiconductor mounting substrate comprising a metal substrate and a conductive layer composed of a plurality of dissimilar metal layers laminated on an insulating layer with a molybdenum layer inside the conductive layer. A semiconductor mounting circuit board characterized by.