JPH0720685B2 - Method for manufacturing ceramic coat laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a laminated board for a printed wiring board.

(Prior Art) Conventionally, a phenol resin laminated board and an epoxy resin laminated board have been often used as a printed circuit board. However, recently, with high performance and miniaturization of electronic devices, high density mounting is desired, and substrate materials are strongly required to have characteristics such as high thermal conductivity, high heat resistance, low thermal expansion coefficient, and high dimensional stability. It has started to be done.

On the other hand, conventional organic substrates such as phenol resin and epoxy resin have poor thermal conductivity and thus lack heat dissipation, have a large coefficient of thermal expansion and poor dimensional stability, and have poor heat resistance. It is not used for such purposes. Therefore, attention has been paid to a ceramic substrate such as alumina, or a metal base or metal core substrate whose surface is covered with an insulating layer using a metal plate as a core material. Further, from the viewpoint of heat resistance, a substrate using a heat resistant thermoplastic resin such as a polyimide resin or polyether ether ketone or polysulfone has been developed in place of the conventional phenol resin or epoxy resin substrate.

(Problems to be Solved by the Invention) However, there are various problems with these substrates. That is, a ceramic substrate such as alumina is superior to an organic substrate in terms of thermal conductivity, heat resistance, and coefficient of thermal expansion, but the manufacturing process is complicated and the shrinkage during sintering is large, so the dimensional accuracy is high. Difficult to work, poor workability such as inability to drill, fragile, and the size of the substrate is limited, so a large substrate cannot be obtained. There are drawbacks such as being expensive. In addition, since the metal base substrate using the metal plate as the core material and the metal core substrate are in contact with the conductor portion which becomes the circuit by the insulating layer made of resin, the high thermal conductivity of the metal core cannot be fully utilized, and However, the heat resistance of the surface is not sufficient. Further, since the core material is a conductive metal plate, it is difficult to form the through holes, and a very complicated manufacturing process is required to form the through holes. Further, although the heat resistance of the heat resistant resin substrate is improved as compared with the conventional product, the heat conductivity is not changed, so that the heat dissipation effect cannot be expected.

The present invention improves these drawbacks, takes in the advantages of the conventional ceramic substrate and the organic substrate, and further improves these disadvantages, the same manufacturing and processing methods as the conventional organic substrate are possible, It is intended to provide a method for inexpensively obtaining a substrate having excellent conductivity and heat resistance and a body thermal expansion coefficient.

(Means for Solving Problems) In the present invention, a ceramic is sprayed on a copper foil to form a ceramic layer, and pores of the ceramic layer are impregnated with an uncured thermosetting resin, and then the copper foil is formed. The prepreg is laminated so as to be in contact with the ceramic layer side, and is thermocompression-molded to be integrated, and a ceramic sprayed layer having pores sealed with a resin is provided between the copper foil and the organic substrate.

There are other ceramic coating methods such as CVD, PVD, and sol-gel method for forming the ceramic layer on the copper foil by thermal spraying. Among these, thermal spraying has the fastest film formation rate and high productivity, Moreover, there is no restriction on the sprayed area, and it is possible to perform ceramic coating on a large area. Gas spraying, plasma spraying, reduced pressure plasma spraying, water plasma spraying and the like can be applied to the ceramic spraying.

The reason why the ceramic sprayed layer thus obtained is impregnated with the uncured thermosetting resin is to seal the pores existing in the ceramic sprayed layer. Unlike the sintered body, the ceramic sprayed layer generally has 5 to 15 vol% of pores. For this reason, if the pores are not sealed and thermocompression molded together with the prepreg, the pores inevitably remain in the ceramic sprayed layer, the water supply rate is large, and therefore the insulation resistance during moisture absorption,
The characteristics such as dielectric characteristics and soldering heat resistance are greatly degraded. Therefore, it is necessary to seal the pores in the ceramic sprayed layer. As a sealing method, a low-viscosity uncured thermosetting resin is applied to the ceramic sprayed layer on the copper foil by brushing, spraying, applying by a doctor blade method, etc.
After that, a method of more completely impregnating, sealing, and curing by pressurization at the time of thermocompression molding with a prepreg is most suitable. By sealing the ceramic sprayed layer with resin, the adhesion between the copper foil and the ceramic layer is also greatly improved. The adhesion of ceramic sprayed to metal is affected by pretreatment conditions such as plast, but it depends on the type of metal,
It is said that the adhesion strength to copper or copper alloy is the lowest. Therefore, if the ceramic layer is not sealed with resin, sufficient adhesion of the copper foil to the ceramic layer cannot be obtained. However, when the resin is sealed, the resin penetrates to the surface of the copper foil, which adheres to the copper foil and greatly improves the adhesion.

Epoxy resin, phenol resin, polyimide resin, melamine resin, unsaturated polyester resin, vinyl ester resin, etc. can be used as the thermosetting resin for sealing the ceramic sprayed layer, but in order to obtain the greatest adhesive strength with the prepreg. It is preferable to use the same type of resin as the resin of the prepreg. These resins are desired to have a low viscosity because they are required to have permeability for the purpose of sealing, and they may be diluted with a solvent before use. In terms of productivity, if these resins become sticky after sealing, the handling will be poor, and if diluted with a solvent, residual solvent will cause problems during pressing. It is better to avoid stickiness at room temperature. However, if it is completely cured by heating, the adhesiveness with the prepreg deteriorates, so this must be avoided.

Alumina, which is most widely used as a ceramic substrate, is suitable as the ceramic sprayed on the copper foil in the present invention, but other electrically insulating ceramics such as spinel, mullite, beryllia, silicon carbide, zirconia, and aluminum nitride. Is used.

The resin of the prepreg is preferably an epoxy resin or a polyimide resin from the viewpoint of electrical characteristics and molding processability, but in addition, a thermosetting resin such as phenol resin, unsaturated polyester resin, melamine resin, vinyl ester resin, or polysulfone, Thermoplastic resins such as polyether ether ketone, polyether sulfone and polyether imide can be used. Further, as the fiber, in addition to commonly used glass fiber, Kepler fiber, paper, SiC fiber, silica fiber or the like can be used.

(Function) Since the laminate obtained by the method of the present invention has the ceramic layer on the surface of the organic substrate, it has a small coefficient of thermal expansion, which is excellent in heat dissipation, heat resistance and surface hardness. Furthermore, since the pores of the ceramic layer are sealed with resin, the water absorption rate is lower than that of the conventional organic substrate, the electrical and mechanical properties at the time of heat absorption are good, and the adhesion between the copper foil and the ceramic layer is sufficient. is there.

Further, the circuit can be easily formed by forming a resist layer on a copper foil and etching the same as in the conventional copper-clad laminate, and since it is possible to drill a hole, a through hole can be formed. It is easy to form.

Hereinafter, the present invention will be described with reference to examples.

(Example) FIG. 1 is a laminated constitutional view of a ceramic sprayed copper foil and a prepreg which have been sealed with a resin, and FIG. 2 is a schematic sectional view of the obtained laminated plate.

Alumina sprayed layer 2 was formed by spraying alumina to a thickness of about 100μ on a copper foil 1 having a thickness of 35μ by plasma spraying. The alumina sprayed layer of this alumina sprayed copper foil was sprayed with a solution prepared by diluting the same epoxy resin as the prepreg used for lamination with a solvent to penetrate and impregnate the alumina sprayed layer. Then, the solvent was removed by heating at 170 ° C. for 2 minutes, and the resin was B-staged to obtain a sealed alumina sprayed copper foil.

The alumina sprayed copper foil subjected to the sealing treatment and the glass cloth / epoxy resin impregnated prepreg 4 were stacked in the laminated structure shown in FIG. 1 and subjected to thermocompression molding to obtain a laminated plate having the structure shown in FIG.

The thus obtained laminate has an alumina layer on the surface of the glass fiber base epoxy resin 5, and further has a copper foil layer on the alumina layer.

JIS C6481 copper foil peeling strength of this laminated board is 1.5 kg / c
The paper feed rate was 0.04%. This laminated board was capable of forming a circuit by etching, drilling holes, and forming through holes in the same manner as a general glass fiber-based epoxy resin copper-clad laminated board.

In addition, it has excellent heat dissipation due to the presence of an alumina layer with good thermal conductivity in contact with the circuit, has high heat resistance and surface hardness, and has a low coefficient of thermal expansion because of the low thermal expansion of alumina. We were able to.

(Comparative Example) A laminated plate was produced in the same manner as in the example except that the alumina sprayed layer was not sealed with the resin under the same conditions.
JIS C6481 copper foil peeling strength of the obtained laminate is 0.1k
It was extremely low at g / cm, and the water absorption rate was 0.35%, indicating a significant decrease in insulation resistance during water absorption.

(Effect of the Invention) By the method of the present invention, a laminate having a ceramic layer on its surface as a base of a conventional organic substrate can be easily manufactured at low cost. The laminated plate obtained by the present invention has excellent characteristics, and circuits, through holes, etc. can be formed in the same manner as in the conventional organic substrate, and the conventional organic substrate, ceramic substrate, and metal substrate can be used. It can solve the problems of the base and metal core substrates.

[Brief description of drawings]

FIG. 1 is a laminated constitution view of a ceramic sprayed copper foil sealed with a resin and a prepreg, and FIG. 2 is a schematic sectional view of a laminated plate obtained by the present invention. DESCRIPTION OF SYMBOLS 1 ... Copper foil, 2 ... Alumina sprayed layer 3 ... Sealed resin, 4 ... Prepreg 5 ... Glass fiber base epoxy resin

Claims (6)

[Claims] 1. A ceramic layer is formed by spraying a ceramic on a copper foil, and the pores of the ceramic layer are impregnated with an uncured thermosetting resin. Then, the copper layer is contacted with the ceramic layer side of the copper foil. A method for producing a ceramic-coated laminate, comprising laminating a prepreg on a sheet and thermoforming. 2. The method for producing a laminated plate according to claim 1, wherein the ceramic contains alumina as a main component. 3. The laminated board according to claim 1, wherein the resin with which the ceramic layer formed on the copper foil is impregnated is mainly composed of the same kind of resin as the resin of the prepreg used for lamination. Production method. 4. The method for producing a laminated board according to claim 1, wherein the resin of the prepreg is an epoxy resin. 5. The method for producing a laminated board according to claim 1, wherein the resin of the prepreg is a polyimide resin. 6. The method for producing a laminated board according to claim 1, wherein the fibers of the prepreg are glass fibers.