JPH02253940A - Manufacture of ceramic composite copper clad laminated sheet - Google Patents

Abstract

PURPOSE:To obtain a printed wiring board material which can cope sufficiently with making of an electronic apparatus into high density, high output and high capacity, by a method wherein after formation of a ceramic layer by performing flame spray coating of ceramic at least on one side of glass cloth, a plurality of prepregs are formed by infiltrating resin into the glass cloth and a copper foil is put on the laminated outermost layer for hot press molding. CONSTITUTION:Alumina layer is formed on one side of glass cloth by performing flame spray coating with a plasmic flame spray device. Epoxy resin is infiltrated into glass cloth having an obtained alumina layer, dried and cast into a stage B for a prepreg. Then a glass cloth base epoxy resin prepreg 1 having an alumina layer 2 into which epoxy resin is infiltrated is laminated along with an electrolytic copper foil 3 and a ceramic composite copper clad laminated sheet is obtained. This laminated sheet can be bored, possesses a low thermal expansion coefficient and is superior in dimensional stability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a copper-clad laminate used for printed wiring boards.

(Prior art) Copper-clad laminates used for printed wiring boards are currently made of so-called plastic-based laminates such as paper-based phenol resin laminates, glass cloth-based epoxy plum resin laminates, or glass cloth-based polyimide resin laminates. Boards are the mainstream.

However, in recent years, there has been remarkable progress in the miniaturization and higher performance of electronic devices, and the requirements for heat resistance, heat dissipation, dimensional stability, etc. for laminate materials have become stricter, and there are many things that conventional laminates cannot meet. It has become to.

For this reason, ceramic substrates such as alumina, aluminum nitride, silicon carbide, etc., which are different from conventional plastic laminates, or aluminum, steel, copper, etc.
2. Description of the Related Art Metal base substrates, in which a thin plastic insulating layer is formed on the surface of a metal plate such as 42 alloy, are used in various fields that cannot be handled by plastic laminates.

(Problem to be solved by the invention) However, while these inorganic substrates have features that cannot be obtained with plastic substrates, ceramic substrates have poor processability such as drilling and cutting, are brittle, and are large. However, they have the disadvantage that they cannot be sintered and are limited in size, making circuit formation complicated. Further, metal-based substrates have drawbacks such as difficulty in forming through holes.

For this reason, each of these materials has its own advantages and disadvantages, and it is thought that by combining ceramic and plastic materials, it would be possible to compensate for the drawbacks of each and obtain a material that combines the features of each.

One possible method is to bond a ceramic substrate and a plastic substrate together, but in this method, the layer height is low because ceramic and plastic are completely different forest materials, and their coefficients of thermal expansion are also significantly different. The adhesion is not sufficient and it is difficult to obtain a product that can withstand practical use. Another method is to mix ceramic powder into the resin. However, even in this method, since the ceramic does not form a layer but is simply dispersed in the resin, little improvement in the thermal expansion coefficient or other properties can be expected.

In view of these problems, the present invention provides a method for manufacturing a ceramic composite copper-clad laminate having new characteristics not found in conventional laminated sheets by combining ceramic and plastic materials.

(Means for Solving the Problems) In other words, the present invention involves thermally spraying ceramic onto glass cloth, which is the base material of the laminate, in order to obtain a ceramic composite copper-clad laminate in which a ceramic layer is formed between the layers of a plastic laminate. A ceramic layer is formed by this process, and the thus obtained glass cloth having the tack layer is impregnated with a resin, dried, and B-staged to obtain a prepreg. This method is characterized in that the prepreg having the ceramic layer obtained in this manner is hot-press molded together with copper foil.

In the present invention, the ceramic layer is formed by thermal spraying glass cloth frosted ceramic in order to obtain high adhesion between the resin and the ceramic layer. The surface of the ceramic layer formed by the solvent is rough, and the inside thereof is porous and has continuous pores. Therefore, when the lamic layer formed by thermal spraying is impregnated with resin, the resin easily impregnates into the pores.

For this reason, the ceramic and resin form a good composite, and since the surface of the ceramic layer is rough, the adhesion area is large, resulting in high adhesion that cannot be obtained with ordinary ceramic and resin.

As the ceramic spraying method, a gas spraying method, a plasma spraying method, a reduced pressure plasma spraying method, etc. can be applied. In addition, alumina, which has good electrical properties and is widely used as a ceramic substrate, is suitable for thermal spraying, but other electrical materials such as mullite, spinel, zirconia, calcia, silica, barium titanate, ittria, and cordierite are also suitable. Insulating ceramic can be used.

The resin to be impregnated into the glass cloth with ceramic formed by thermal spraying is preferably epoxy resin or polyimide resin, which are widely used as glass cloth base laminates, or other materials such as phenol resin, melamine resin, Thermosetting resins such as unsaturated polyester resins and vinyl ester resins, or thermoplastic resins such as Teflon resins, polysulfones, polyetherimides, polyetheretherketones, and polyethersulfones can be used.

(Function) In the present invention, the ceramic layer formed on the glass cloth by thermal spraying has the following two features.

The first is that the ceramic layer and resin provide a high level of title quality. This is because the ceramic layer formed by thermal spraying is porous and the resin is impregnated into its pores, and the surface of the ceramic layer is rough so that the adhesive area with the resin is very large.

Second, since the thermally sprayed ceramic forms a layer, the inherent characteristics of the ceramic can be fully brought out, and characteristics that cannot be obtained by mixing ceramic with resin as a filler can be obtained. For example, looking at the coefficient of thermal expansion, the coefficient of thermal expansion is almost the same when ceramic is mixed with resin as a filler and when no filler is added. However, in the ceramic composite copper-clad laminate manufactured by the method of the present invention, since the ceramic is layered, the coefficient of thermal expansion in the plane direction is small, and the thermal expansion of the resin is suppressed because the coefficient of thermal expansion of the ceramic layer is small. Moreover, since the ceramic layer and the resin layer are strongly bonded, the cost can be lowered.

As described above, the ceramic composite copper-clad laminate obtained by the method of the present invention has a lower coefficient of thermal expansion in the planar direction than conventional plastic laminates, and therefore has excellent dimensional stability.

In addition, although it is impossible to drill holes in ceramic substrates such as alumina, the ceramic composite copper clad laminate of the present invention has a thin ceramic layer dispersed between resins. Holes can be drilled using a drill. Incidentally, although the thickness of the ceramic layer formed on the glass cloth does not limit the scope of the present invention, it is 10μ.
A range of 50 μm from m to 50 μm is preferred. When the thickness of the ceramic layer is less than 10 μm, the ceramic layer is difficult to be continuous and therefore not layered, so that the effect of reducing the coefficient of thermal expansion is small.

Moreover, if it exceeds 50 μm, the ease of drilling etc. will deteriorate, and the flexibility of the glass cloth on which the ceramic layer is formed will be impaired, resulting in cracks or breakage during resin processing or even when handling as a prepreg. This is because it is easy to handle and difficult to handle.

(Example) An example of the present invention will be described below based on FIGS. 1 and 2. Alumina (purity 99.696) was sprayed onto one side of the glass cloth using a plasma spraying device (Plasma Dyne System Model 3600-80R, manufactured by Plasma Dyne Inc., USA) to form an alumina layer with a thickness of 15 μm. The thus obtained glass cloth having the alumina layer was impregnated with epoxy resin, dried, and B-staged to form a prepreg. The thickness of this prepreg after hot-press molding is 0.2 m based on glass cloth based epoxy resin, and 15 μm for the epoxy resin-impregnated alumina layer.

Next, as shown in FIG. 1, a glass cloth base epoxy resin prepreg l having an epoxy resin impregnated alumina layer 2
was laminated with an electrolytic copper foil 3 having a thickness of 18 μm, and hot-press molded for 2 hours at a molding temperature of 170° C. and a molding pressure of 5 (Hg/cd) to obtain a ceramic composite copper-clad-like laminate having the configuration shown in Fig. 2. Obtained.

The thickness of this laminate was 0.9 m, and the total lumen of the three alumina layers was 60 μm. The coefficient of thermal expansion in the plane direction was measured to be 9.5×10//°C. On the other hand, the coefficient of thermal expansion in the plane direction of the glass cloth-based epoxy resin laminate without aluminum resin is xtsxxo7℃
Met.

Further, as a result of examining drilling using a drill, it was found that the laminate of the example could be drilled in the same way as a conventional glass cloth base epoxy/resin laminate.

Next, a thermal shock test using the hot oil method was conducted to evaluate the porosity of the alumina layer and epoxy resin layer. This is a test in which a sample is immersed in silicone oil at 260°C for 20 seconds and then immediately immersed in cold water at 20°C for 15 seconds. Although the test was carried out up to 100 cycles, no defects such as peeling between the alumina layer and the resin layer, cracks, or blisters were observed.

(Effects of the Invention) As described above, the ceramic composite copper-clad laminate obtained by the method of the present invention successfully combines ceramic and plastic, improves the drawbacks of each, and combines the features of each other. Therefore, it is possible to obtain a printed wiring board material that can sufficiently respond to higher density, higher output, and higher performance of electronic devices.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the laminated structure of glass cloth prepreg having ceramic islands and copper foil in an example of the present invention, and FIG. 2 is a schematic cross-sectional view showing the structure of the obtained ceramic composite copper-clad laminate. It is. Explanation of symbols 1...Epoxy resin impregnated glass cloth 2...Epoxy resin impregnated alumina layer 3...Copper foil

Claims (4)

[Claims] 1. After spraying ceramic on at least one side of the glass cloth to form a ceramic layer, the glass cloth is impregnated with resin to form a plurality of prepregs, the plurality of prepregs are laminated, and a copper foil is applied to both or one side of the outermost layer. A method for manufacturing a ceramic composite copper-clad laminate, which comprises placing a ceramic composite copper-clad laminate and hot-pressing it. 2. 2. The method of manufacturing a ceramic composite copper-clad laminate according to claim 1, wherein the ceramic to be thermally sprayed has alumina as a main component. 3. 2. The method for manufacturing a ceramic composite copper-clad laminate according to claim 1, wherein the resin impregnated into the ceramic-sprayed glass cloth is an epoxy resin. 4. 2. The method for manufacturing a ceramic composite copper-clad laminate according to claim 1, wherein the resin impregnated into the ceramic-sprayed glass cloth is a polyimide resin.