JPH04119684A - Metal circuit board - Google Patents

Abstract

PURPOSE:To obtain a metal circuit board where an electrical insulating layer is thin, uniform in thickness, and excellent in electrical insulation and reliability by a method wherein an aromatic polyamide paper is impregnated with heat resistant resin and dried up into prepreg, which serves as an electrical insulating layer. CONSTITUTION:A board of optionally selected metal is formed 0.5-2.5mm in thickness, where the thickness of the board is determined basing on uses. Any kinds of heat resistant resin can be used for the heat resistant resin concerned, and resin of a kind can be used or two or more kinds of resins are mixed together to be utilized. Technora (product of Teijin Co) can be used as an aromatic polyamide paper. A metal foil, a metal plating layer, or a conductive paste which can be formed into a circuit pattern can be used as a conductive layer. An aromatic polyamide paper is impregnated with heat resistant resin and dried up into prepreg. A few sheets of prepreg are laid on a metal board, a copper foil or the like is made to overlap the prepreg, and the laminate concerned is formed into a circuit metal board through thermocompression.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention provides a circuit metal suitable for flip-chip mounting, etc., which has excellent electrical insulation, heat dissipation, adhesion, surface smoothness, etc. Regarding the board.

(Prior Art) In recent years, as semiconductor active components have become highly integrated, heat generation from the components has become a major problem. In addition, with the trend toward smaller packages, packages such as COB, chip carriers, and flip chips that allow heat generated by chips to escape to the substrate are increasing.

Furthermore, advances in high-density packaging technology have increased the number of components mounted per unit area of a board, and the amount of heat generated per unit area of the board has also increased dramatically.

Therefore, the heat dissipation of a circuit board is one of the most important factors.

In general, resin laminate molded bodies based on metal plates such as aluminum and iron have excellent heat dissipation, electrical properties, and mechanical properties, and are therefore used as substrates for -film circuits and hybrid integrated circuits. Among these molded products, copper foil coated with an adhesive on the back side is laminated and bonded onto a metal plate, and the adhesive layer coated on the copper foil is used as an electrical insulation layer to form a circuit board (hereinafter referred to as a coated board) or a thermal There is a circuit board (hereinafter referred to as a prepreg board) in which a metal foil is laminated and bonded onto a metal plate via a glass paper cloth impregnated with a curable resin, and a cured prepreg is used as an electrical insulating layer.

However, although coated substrates have a thin electrical insulating layer and are advantageous in terms of heat dissipation, it is difficult to adjust the thickness of the adhesive to a uniform and desired thickness with high precision when manufacturing circuit boards. However, if the thickness is not uniform, pinholes may occur, resulting in poor insulation properties. Another drawback is that the electrical insulating layer tends to crack when bent.

On the other hand, with prepreg boards, the electrical insulating layer is made of glass cloth or glass paper impregnated with thermosetting resin, so the surface is not smooth and the thickness depends on the thickness of the glass cloth or glass paper. Because it is a dust chamber, it is thicker than a coated substrate, and although it has advantageous insulation properties, it has the disadvantage of poor heat dissipation. Furthermore, crow cloth and crow paper have poor impregnability with thermosetting resins, poor adhesion with thermosetting resins and poor adhesion with metal plates, and may peel off when bent, resulting in mechanical problems. It also had the disadvantage of reduced strength.

(Problems to be Solved by the Invention) The present invention has been made in order to eliminate the above-mentioned drawbacks. The purpose is to provide a highly reliable metal substrate for circuits with excellent bendability, heat dissipation, adhesion, mechanical properties, coefficient of thermal expansion, etc.

[Structure J of the Invention (Means for Solving the Problems) As a result of extensive research in an attempt to achieve the above object, the present inventors have developed a method using a small number of gutspregs made of an aromatic polyamide paper substrate and a heat-resistant resin. The present invention has been completed based on the discovery that the above object can be achieved by the following methods.

That is, the present invention provides a metal board for circuits having a conductive layer on at least one side of a metal plate via an electrically insulating layer, in which a prepreg in which aromatic polyamide paper is impregnated with a heat-resistant resin and dried is used as the electrically insulating layer. This is a circuit metal substrate characterized by:

The metal plate used in the present invention may be made of any metal; in terms of numbers, aluminum plates, various corrosion-resistant aluminum plates, copper plates, stainless steel plates, brass plates, silicon steel plates, etc. are used. The thickness of the metal plate is not particularly limited, but the numerical thickness is approximately 0.5 to 2.51I11, and is selected depending on the purpose of use. It is desirable that the surface of this metal plate be roughened in order to improve its adhesion with the electrical insulating layer, but if the type of metal plate has high adhesion, the surface may not be roughened. The surface roughening method may be a mechanical method, a chemical method, or any other method.

The heat-resistant resin used in the present invention is not particularly limited as long as it is a heat-resistant resin, and examples thereof include heat-resistant epoxy resins, triazine resins, polyimide resins, etc., and these may be used alone or in a mixture of two or more kinds. I can do it. These heat-resistant resins can contain polyvinyl butyral resin, heat-resistant elastomer, phenoxy resin, etc. to further improve adhesion, and inorganic fillers such as alumina to improve heat dissipation. , silica, magnesia, zirconia, boron nitride, etc. can be used.4 If it is necessary to form a conductor circuit by plating or the like on the electrically insulating layer, the resin of the electrically insulating layer should be subjected to pretreatment such as roughening. It can be carried out.

Examples of the aromatic polyamide paper used in the present invention include Technora (manufactured by Ontaisha, trade name).

As the conductive layer used in the present invention, any material that can form a circuit, such as a metal foil, a metal plating layer, or a conductive paste layer, can be used. In particular, when using metal foil such as copper foil as a conductive layer, the metal foil can be placed on the outermost layer of a stack of metal plates and prepreg, and the metal foil can be laminated and molded as one piece, making it suitable for mass production. This has great manufacturing advantages.

The circuit metal substrate of the present invention is prepared by applying a heat-resistant resin to the above-mentioned aromatic polyamide paper, impregnating it, and drying it to prepare a prepreg. A circuit metal board can be manufactured by stacking a small number of sheets of this prepreg on a metal plate, further stacking a copper foil or the like on top of the prepreg, and molding under heat and pressure by a conventional method.

(Function) The metal substrate for circuits of the present invention has been able to achieve the original purpose by using aromatic polyamide vapor and a heat-resistant resin as a matrix resin.

That is, aromatic polyamide paper is more flexible and has better resin impregnation properties than glass substrates, and as a result, it can improve adhesion to metal plates. Therefore, the bending ability is high and peeling is less likely to occur.

Additionally, since prepregs can be made thinner than glass substrates, heat dissipation can be improved. Furthermore, the surface smoothness, x
It also has excellent thermal elongation in the y-force direction, which is an important factor in ultra-high-density packaging and flip-chip packaging.

On the other hand, aromatic polyamide paper has disadvantages in that it has inferior heat resistance and large thermal expansion in one direction compared to glass substrates.

Therefore, Mad 1! This method uses a heat-resistant resin as the Tux resin to compensate for its drawbacks.

(Example) Next, the present invention will be explained by examples, but the present invention is not limited by these examples.
Polished and roughened by liquid honing using abrasive grains.

A prepreg was made by coating, impregnating, and semi-curing heat-resistant epoxy resin varnish on aromatic polyamide paper, Technora (manufactured by Ontaisha, trade name).

Layer this prepreg on the rough surface of the aluminum plate,
Further, a copper foil having a thickness of 18 μl was layered on top of the copper foil, and a metal substrate for circuits was manufactured by integrally molding the foil under heat and pressure using a conventional method.

Example 2 One side of a silicon steel plate having a thickness of 0.5 IN11 was polished and roughened using #100 sandpaper. Gripreg was made by applying polyimide resin varnish to aromatic polyamide paper Technora (described above), impregnating it, and semi-curing it.

This prepreg was layered on the rough surface of the silicon steel plate, and a copper foil with a thickness of 18 μm was layered on top of the prepreg, and a metal circuit board was manufactured by integrally molding the prepreg with heat and pressure using a conventional method.

Comparative Example 1 One side of an aluminum plate having a thickness of 1.2i11 was polished and roughened with #100 sandpaper. Aramid paper was coated with an epoxy resin varnish consisting of 100 parts by weight of epoxy resin Epikote 1001 (manufactured by Yuka Shell Co., Ltd., trade name), 4 parts by weight of dicyandiamide, 0.2 parts by weight of benzyldimethylamine, and methyl ethyl ketone.
A prepreg was made by semi-curing. This Gripreg is placed on top of the aluminum plate, and on top of that, a thickness of 18
A circuit metal board was manufactured by overlapping #4 μm foils and integrally molding them under heating and pressure using a conventional method.

Comparative Example 2 A circuit metal substrate was manufactured in the same manner as in Comparative Example 1 except that glass vapor was used instead of aramid paper.

Regarding the circuit metal substrates manufactured in Examples 1 and 2 and Comparative Examples 1 and 2, the solder heat resistance, peel strength, dielectric breakdown voltage,
Tests were conducted on bendability, coefficient of thermal expansion, and heat dissipation.
The results are shown in Table 1, and the present invention showed excellent characteristics in all cases, confirming the effects of the present invention.

[Effect of the Invention 3] As is clear from the above explanation and Table 1, the circuit metal substrate of the present invention has a thin and uniform electrical insulating layer by using aromatic polyamide paper and heat-resistant resin. , heat dissipation was also improved. In addition, aromatic polyamide paper is well impregnated with heat-resistant resin, so it has excellent electrical insulation even though the thickness of the insulating layer is thinner, and has excellent mechanical properties, adhesion, and bending properties. It is possible to produce a highly reliable circuit metal substrate with a low coefficient of thermal expansion, and is suitable for ultra-density packaging and prep-chip packaging.

Patent applicant: Toshiba Chemical Corporation Agent Patent attorney 1) Eini

Claims (1)

[Claims] 1. A metal board for circuits having a conductive layer on at least one side of a metal plate via an electrically insulating layer, characterized in that the electrically insulating layer is made of a prepreg obtained by impregnating aromatic polyamide paper with a heat-resistant resin and drying it. Metal substrate for circuits.