JPS58138061A - Substrate for integrated circuit - Google Patents

Abstract

PURPOSE:To improve heat-resisting property and radiating property, and to enable wire bonding directly by forming the substrate in the three layer structure of a metallic or a composite alloy tape and a ceramic thin layer and an aluminum film. CONSTITUTION:Organic matter is not used but the metallic foil 3 having sufficient flexibility is used as a substrate, and three layer structure is obtained by a material in which the metallic foil is coated with the electric insulating ceramic film 4 and the ceramic layer is coated with the aluminum film 5. The thickness of the metallic foil 3 is limited to 0.01-0.10mum because it requires sufficient flexibility. The quality of materials is selected in response to request to the thermal expansion characteristics and heat radiation characteristics of the IC, but materials, such as Kovar, every kind of copper alloys such as a 42 alloy (42% Ni-Fe), etc. are effective. Oxides, such as BN, Al2O3, AlN, SiC, Si3N4, Y2O5, etc. with 0.1-3mum thickness are available as the coating ceramic layer 4. 0.1mu-3mu is preferable as the thickness of the ceramic coating layer. The aluminum foil 5 requires 3-30mum thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substrate material used for various ICs such as tape carrier type mounting type ICs and hybrid ICs. The present invention provides a substrate that can significantly improve the range of applications.

Tape carrier type IC mounting is attracting attention among IC mounting technologies in terms of continuous IC mounting and improvement in bonding speed. However, since organic materials such as polyimide are used as substrate films, they do not have sufficient heat resistance and heat dissipation, making it difficult to apply them to power IC applications, for which demand has been increasing in recent years, and to increase the density of component mounting. The reality is that the scope of practical use is limited.

The present invention aims to eliminate the drawbacks of such a tape carrier type IC mounting substrate film and provide a substrate film having good heat resistance and heat dissipation properties.

Figure 1 shows a tape carrier type IC that is currently widely used.
This shows a partial cross-sectional structure of a substrate film used for mounting, in which a copper foil 2 is bonded onto a polyimide film 1. This copper foil is used as a lead frame by forming a circuit using a resist method. However, with this method, the bondability between polyimide film and copper foil is 150°.
Polyimide film deteriorates significantly if exposed to temperatures above ℃ for a long period of time, and the thermal conductivity of the polyimide film itself is poor, so there are many problems in terms of high-temperature processing in the IC assembly process and heat dissipation generated during IC operation. .

FIG. 2 shows a partial cross-sectional structure of a tape carrier type IC mounting substrate film according to the present invention. As the substrate, a sufficiently flexible metal foil 3 is used instead of an organic material, and an electrically insulating film is used as the substrate. After coating the ceramic layer 4, an aluminum film 5 is coated on the ceramic layer.
It shows a three-layer structure. Since the metal foil 8 needs sufficient flexibility, its thickness is set to 0. It is limited to O1 to 0.10jljL. The material is selected depending on the requirements for the thermal expansion and heat dissipation characteristics of the IC, and includes Kovar, 42 alloy (4296Ni-Fe), various copper alloys, Cu clad 4
Materials such as 2 alloy clad Cu, Cu clad stainless clad Cu% 42 alloy, and 42 alloy clad steel flood 42 alloy are effective. Moreover, the thickness of the upper ramic layer 4 is 0.1 to 8 μm.
m, BN, fiJ@OB, AjN, SiC,5
One or more oxides selected from iBN4, YgOs are useful and can be selected depending on the required characteristics of the circuit board. The thickness of the seven ramic coating layers is 0.1
If it is less than 8μ, there will be problems in terms of insulation, and if it is more than 8μ, there will be problems in terms of high coating cost and flexibility and adhesion strength.

The aluminum foil 5 coated on the seven lamic coating layers is 8
A thickness of 280 μm is required, which is based on the thickness required for forming the conductive circuit.

Here, aluminum was used as the circuit forming material by A.
Since wire bonding using thin wires can be performed directly and easily, die bonding of Si chips can be performed using a paste method.

As a coating method for ceramic and aluminum films, physical vapor deposition (PV) is used because of its thin, uniform, and stable adhesion.
The effect of the present invention is remarkable when a vapor phase plating method such as c method) or chemical vapor deposition method (CVD method) is used.

However, an adhesive method or a pressure bonding method can also be used to cover the aluminum film.

This will be explained below using examples.

2. AjgOs thin film was deposited on copper clad 42 alloy clad copper with a plate thickness of 0.08jlK using the ion blasting method.
After 0μm coating, 8μm coating by ion sputtering method.
coated with an aluminum film.

The substrate is a laminated metal tape with a thermal expansion coefficient of 7.
In order to set OX 10-6/deg, the copper ratio (cross-sectional area ratio) was set to B096. Ion blating for Aj 2OB coating uses A-208 sintered body as the raw material, evaporates it by electron beam heating, and increases the oxygen pressure to 4 X I P'
Torr, 18.56MHz, 100-200
A high frequency power of W was applied to ionize a part of the evaporated substance, and the substrate was heated to 200"C to form Ajg08 with a thickness of 1.0
μm coated, withstand voltage 3Mv/F+! A flexible film with good insulation properties, adhesion, and flexibility was produced. The sputtering conditions for forming the aluminum film were as follows: aluminum with a purity of 99.99wt96 was used as the target, and the substrate was heated to 100"C in an argon gas atmosphere. The substrate film thus produced was heated to 200"C. Even when exposed for a long time, its properties did not deteriorate, the coating layer did not peel off, and the flexibility was sufficient.

As explained above, after coating a metal or composite alloy tape with sufficient thermal conductivity and required thermal expansion characteristics and flexibility as a film with a lamic film having electrical insulation properties, By coating with an aluminum film for circuit formation, it is possible to create a substrate material used for tape carrier type ICs that has good heat resistance and heat dissipation properties and can be directly wire bonded. It has become possible to significantly expand the scope of application of the mounting method.

[Brief explanation of drawings]

FIG. 1 is a partial view of a conventional substrate film, and FIG. 2 is a partial partial view of a substrate film according to the present invention. l: polyimide film, 2: copper foil, 8: metal foil, 4:
Ceramic film, 5 Ni aluminum foil. Yoshi I diagram

Claims (3)

[Claims] (1) Plate thickness 0. A thin electrically insulating ceramic layer with a thickness of 0.1 to 3 μm is placed on a flexible metal or composite alloy tape of O1 to 0.1041, and an aluminum film with a thickness of 8 to 80 μm is placed on top of the thin ceramic layer with a thickness of 0.1 to 3 μm. An IC substrate characterized by having a three-layer structure coated with a thickness. (2) The ceramic that is the middle layer of the three layers is BN, Ajg
The IC substrate according to claim (1), characterized in that it is a ceramic thin layer of one or more types of 08°SiC, 5iaN++ Yaks. (3) The IC substrate according to claim (1), wherein the ceramic thin layer which is an intermediate layer among the three layers is coated by a PVD method or a CVD method.