JPH0719941B2 - Ceramic composite copper clad laminate and its manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a copper clad laminate used for a printed wiring board and a method for manufacturing the same.

(Prior Art) Conventionally, a paper-based phenol resin laminated plate, a glass cloth-based epoxy resin laminated plate, a glass cloth-based polyimide resin laminated plate, etc. have been mainly used for a printed wiring board. However, with the recent progress in higher output and smaller size of electronic devices, it is strongly desired to reduce the coefficient of thermal expansion, heat resistance and tracking resistance of printed circuit board materials in order to improve dimensional stability. There is.

To meet such demands, conventional plastic substrates such as glass cloth-based epoxy resin laminates are inferior in terms of thermal expansion coefficient, tracking resistance, heat resistance, etc. Improvement is needed. On the other hand, ceramic substrates such as alumina satisfy these requirements, but have drawbacks such as poor workability and inability to increase the size of the substrate.

Under these circumstances, the present inventors have proposed a ceramic-coated laminated plate in consideration of compounding a conventional plastic substrate and a ceramic substrate (Japanese Patent Laid-Open No. 62-152742).
This is a ceramic layer such as alumina provided between the copper foil and the fiber reinforced plastic layer. Dimensional stability is good because it has a lower coefficient of thermal expansion than conventional plastic substrates, it has excellent heat resistance such as peeling strength and surface strength of copper foil during hot work, or tracking resistance and arc resistance. It has features such as superiority, and although it is not possible with a ceramic substrate, drilling is also possible.

(Problems to be Solved by the Invention) However, a major drawback of the ceramic-coated laminate having such features is that the drill workability is inferior to that of a conventional plastic substrate. That is, φ1.0 mm
If it is about a degree, it can be processed with a carbide drill even though the wear of the drill is great, but if the diameter is about 0.3 mm, the drill is easily broken. For example, if the ceramic layer is made of alumina and has a thickness of 100 μm, the drill will break in about 200 holes.
Therefore, there is a problem in applying it to a printed wiring board having a small diameter hole, and although it has characteristics such as dimensional stability, tracking resistance, and heat resistance, its use is limited.

The present invention provides a ceramic composite copper-clad laminate having the advantages of dimensional stability, tracking resistance, heat resistance, etc., in which this drawback is improved and drill workability is improved.

(Means for Solving the Problems) That is, the present invention provides a thermal spraying layer mainly composed of cordierite between a copper foil and a woven prepreg layer, and thermocompression molding,
A ceramic composite copper-clad laminate having a structure having a thermal spray layer mainly composed of cordierite between a copper foil and a fiber-reinforced plastic layer is characterized. Further, the manufacturing method is such that a ceramic mainly composed of cordierite is sprayed on one surface of a copper foil to form a thermal sprayed layer mainly composed of cordierite, and the woven cloth is in contact with the thermal sprayed layer mainly composed of cordierite. The prepreg is laminated, placed and thermocompressed.

The ceramic provided between the copper foil and the fiber reinforced plastic layer is cordierite because cordierite is softer than alumina and has a low coefficient of thermal expansion. The composition of cordierite is 2MgO ・ 2Al ₂ O ₃・ 5SiO.
₂ , the coefficient of thermal expansion is 0.5 to 2.0 × 10 ^-6 / ° C. That is, by providing a cordierite layer having a low coefficient of thermal expansion, it is possible to suppress the thermal expansion of the fiber-reinforced plastic layer having a high coefficient of thermal expansion, and as a result, the coefficient of thermal expansion of the laminated sheet becomes low and dimensional stability is improved. To do. Further, when alumina is used for the ceramic layer, the alumina is hard and the workability is poor, so that the drill is significantly worn during drilling, and therefore the drill is easily broken. This phenomenon is especially noticeable when the drill has a small diameter. However,
When cordierite is used in place of alumina as the ceramic layer, cordierite is softer than alumina, and therefore wear on the drill during drilling is reduced and the drill is less likely to break. By the way, the Vickers hardness of alumina is about 2500, while that of cordierite is about 70.
0 to 800.

In addition, as a manufacturing method thereof, a method of spraying cordierite on a copper foil to form a cordierite sprayed layer and thermocompressing and integrating this with a woven fabric prepreg is adopted because of the following advantages. Is.

The thermal spraying can be applied by a general thermal spraying method such as a plasma spraying method or a gas spraying method, but it is a method of melting ceramic powder by heat and colliding it with a sprayed object at a high speed to fix it. is there. Thus, the resulting sprayed layer has a structure in which flat particles of ceramic powder, which is a spraying material, are deposited and has 5 to 20 volume percent of pores. In general terms, the presence of these pores is a major drawback for electrical insulation applications. That is, the pores are apt to absorb moisture, and the insulating property when absorbing moisture is deteriorated. However, in the manufacturing method of the present invention, the existence of the pores is a great advantage. This is because when cordierite is sprayed onto a copper foil to form a cordierite sprayed layer, and a woven fabric prepreg is placed on it and hot-pressed, the resin of the woven fabric prepreg softens and melts during hot-press forming. , Impregnate the pores of the cordierite sprayed layer. As a result, the pores of the cordierite sprayed layer are sealed, and the problem of deterioration of the insulation characteristics when absorbing moisture is solved.

Furthermore, the adhesiveness between the ceramic and the resin is a kind of material, and the thermal expansion coefficient is different, which is not good. can get. Also, with the adhesive force between the copper foil and the cordierite sprayed layer still sprayed,
Although not satisfactory for use as a printed wiring board, a strong adhesive force is obtained when the resin reaches the copper foil surface through the cordierite sprayed layer.

As the woven fabric of the woven prepreg used in the present invention, a glass fiber woven fabric used for a general laminated plate is preferable from the viewpoints of its characteristics and price, but other woven fabrics such as aramid fiber and quartz fiber are also used. Can be used. Further, the resin is preferably an epoxy resin or a polyimide resin used in a general laminated board, but in addition, a phenol resin, a melamine resin, an unsaturated polyester resin, a fluorine resin or the like can be used.

The cordierite-based ceramic used in the present invention may be a mixture of other ceramics such as alumina, zirconium, titania, calcia, spinel, mullite, and zircon as long as cordierite is the main component. Although good, the cordierite content is preferably 60% by volume or more. If the amount of cordierite is less than 60% by volume, the improvement effect of drill workability is small, and even if the drill workability is improved,
This is because the dimensional stability is reduced. In order to achieve both drilling workability and dimensional stability, it is necessary that the cordierite content be 60% by volume or more.

(Operation) The ceramic composite copper-clad laminate of the present invention has a thermal spray layer mainly composed of cordierite between the copper foil and the fiber reinforced plastic layer. Low coefficient of thermal expansion (0.5-2.0
× 10 ^-6 / ℃) thermal expansion coefficient of the laminate in order to cordierite layer is present becomes much lower than the conventional copper-clad laminate without cordierite layer to greatly improve the dimensional stability of the substrate be able to. Further, since the cordierite sprayed layer is softer than the alumina sprayed layer, the wear of the drill during drilling is less than that when alumina is used, and therefore the drill is less likely to break. Especially with a small diameter drill, it has a remarkable effect.

Furthermore, since the cordierite sprayed layer that is a ceramic is present immediately below the copper foil, the tracking resistance of the laminated plate,
It has excellent arc resistance and peeling strength of copper foil when heated.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

On the roughened surface of electrolytic copper foil 1 with a thickness of 18 μm (TSTO-18 μm, made by Furukawa Circuit Foil), a plasma sprayer manufactured by US Plasmadyne Corporation, Plasmadyne System 3600-80R type was used for cordierite (PC-MAS / F, manufactured by Nippon Abrasive Co., Ltd.) was sprayed to form a cordierite layer 2 having a thickness of 100 μm. Then, the laminated structure shown in FIG. 1 was subjected to thermocompression molding together with the glass fiber woven epoxy resin prepreg 3 to obtain a ceramic composite copper clad laminated plate having a thickness of 0.4 mm and having a structure shown in FIG.

The coefficient of thermal expansion of the obtained ceramic composite copper-clad laminate was 8.4 × 10 ^-6 ° C ^-1 , and the 4-layer plate press of the 4-layer plate using this ceramic composite copper-clad laminate as the inner layer plate The subsequent dimensional change rate was 0.003%. The coefficient of thermal expansion in the plane direction of the ceramic composite copper clad laminate having an alumina sprayed layer instead of the cordierite sprayed layer was 8.3 × 10 ^-6 ° C ^-1 A dimensional change rate after pressing of a 4-layer plate was 0.003%. It was almost the same. Further, in the conventional copper clad laminate without a ceramic sprayed layer, the coefficient of thermal expansion in the plane direction was 13.7 × 10 ^-6 ° C ^-1 , and the dimensional change rate after pressing the four-layer plate was 0.025%.

Next, when a ceramic composite copper clad laminate with a cordierite sprayed layer was drilled with a 0.35 mm diameter cemented carbide drill, the drill did not break even with 10,000 drilled holes.
On the other hand, in the ceramic composite copper clad laminate with the alumina sprayed layer, the drill was broken at 206 holes. Further, the burr of the copper foil on the drill-through side of the laminated plate is large when alumina is used as the ceramic, and the through-hole plating process was difficult unless the burr portion of the copper foil was removed by polishing. In the case of using cordierite, the burr of the copper foil was almost the same as that of the conventional copper-clad laminate without ceramics, and there was no problem.

(Effects of the Invention) As described above, the ceramic composite copper-clad laminate obtained by the method of the present invention has low thermal expansion, tracking resistance, and hot peeling strength of copper foil compared to conventional copper-clad laminates. It is excellent in comparison, and can greatly improve the drilling workability, which is the biggest drawback of the ceramic composite copper-clad laminate using the alumina sprayed layer on the ceramic.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a laminated structure of an embodiment of the present invention,
FIG. 2 is a schematic sectional view showing the structure of the obtained ceramic composite copper-clad laminate. Explanation of symbols 1 ... Electrolytic copper foil 2 ... Cordierite sprayed layer 3 ... Glass fiber woven epoxy resin prepreg 4 ... Glass cloth base epoxy resin

Claims (8)

[Claims] 1. A ceramic-composite copper-clad laminate characterized in that a thermal sprayed layer mainly composed of cordierite is provided between a copper foil and a woven prepreg layer, and this is thermocompression-molded. 2. The ceramic composite copper-clad laminate according to claim 1, wherein the woven cloth of the woven cloth prepreg is a glass fiber woven cloth. 3. The ceramic composite copper-clad laminate according to claim 1, wherein the resin of the woven fabric prepreg is an epoxy resin. 4. The ceramic composite copper-clad laminate according to claim 1, wherein the resin of the woven cloth prepreg is a polyimide resin. 5. A ceramic mainly composed of cordierite is sprayed on one surface of a copper foil to form a sprayed layer, and a woven fabric prepreg is placed so as to be in contact with the sprayed cordierite layer and thermocompression-molded. A method for manufacturing a ceramic composite copper-clad laminate, which is characterized in that 6. The method for producing a ceramic composite copper-clad laminate according to claim 5, wherein the woven prepreg woven fabric is a glass fiber woven fabric. 7. The method for producing a ceramic composite copper-clad laminate according to claim 5, wherein the resin of the woven fabric prepreg is an epoxy resin. 8. The method for producing a ceramic composite copper-clad laminate according to claim 5, wherein the resin of the woven fabric prepreg is a polyimide resin.