JP2806030B2 - Ceramic composite copper-clad laminate and method of manufacturing the same - 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 producing the same.

(Prior Art) Conventionally, a paper-based phenol resin laminate, a glass cloth-based epoxy resin laminate, a glass cloth-based polyimide resin laminate, and the like have been mainly used as printed wiring boards. However, recently, with the progress of high output and miniaturization of electronic devices,
In order to improve the dimensional stability of printed circuit board materials, it is strongly desired to reduce the coefficient of thermal expansion and to improve heat resistance and tracking resistance.

In response to such demands, plastic substrates such as conventional glass cloth-based epoxy resin laminates have thermal expansion coefficients,
Since tracking resistance, heat resistance, and the like are inferior, improvements are required to cope with high-density mounting. 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 such circumstances, the inventors of the present invention have proposed a ceramic-coated laminate in consideration of combining a conventional plastic substrate and a ceramic substrate (Japanese Patent Application Laid-Open No. 62-152742). In this case, a ceramic layer such as alumina is provided between a copper foil and a fiber-reinforced plastic layer. Excellent dimensional stability due to lower coefficient of thermal expansion compared to conventional plastic substrates, excellent heat resistance such as hot copper foil peeling strength and surface hardness, or excellent tracking resistance and arc resistance It has advantages such as superiority, and although it is impossible 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
If the diameter is small, a carbide drill can be used although the wear of the drill is large, but if the diameter is as small as about φ0.3, the drill is easily broken. For example, if the ceramic layer is made of alumina and has a thickness of 100 μm, the drill breaks at 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 features such as dimensional stability, tracking resistance, and heat resistance, its use is limited.

The present invention is to provide a ceramic composite copper clad laminate which has improved drawbacks, improved drill workability, and has features such as dimensional stability, tracking resistance and heat resistance.

(Means for Solving the Problems) That is, the present invention provides a copper foil and a fiber-reinforced plastic layer obtained by providing a ceramic sprayed layer mainly composed of mullite between a copper foil and a woven prepreg layer and hot-press molding. And a ceramic composite copper-clad laminate having a mullite sprayed layer between the two.

The production method involves spraying a ceramic mainly composed of mullite on one side of a copper foil to form a sprayed layer, laminating and placing a woven prepreg so as to be in contact with the mullite sprayed layer, and hot-press molding. is there.

The reason why the ceramic provided between the copper foil and the fiber-reinforced plastic layer is a ceramic mainly composed of mullite is that mullite is softer and has a lower thermal expansion coefficient than alumina. That is, by providing the mullite layer having a low coefficient of thermal expansion, the thermal expansion of the fiber-reinforced plastic layer having a high coefficient of thermal expansion can be suppressed, and as a result, the coefficient of thermal expansion of the laminated board is reduced, and the dimensional stability is improved. It is. Further, when alumina is used as the ceramic layer, the alumina is hard and the workability is poor, so that the drill is significantly worn during drilling, so that the drill is easily broken. This phenomenon is particularly remarkable when the diameter of the drill is small. However, when mullite is used instead of alumina as the ceramic layer, mullite is softer than alumina, so drill wear during drilling is reduced, and the drill is less likely to break.

In addition, as a method for producing the mullite, a method of spraying a ceramic mainly composed of mullite onto copper foil to form a mullite sprayed layer, and hot-press molding the mullite with a woven prepreg and integrating them is adopted as follows. It is from a great advantage.

Thermal spraying can be applied by the general thermal spraying method used in general ceramic spraying such as plasma spraying and gas spraying.However, ceramic powder is melted by heat and collides with the object to be sprayed at 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 sprayed material, are deposited and has pores of 5 to 20% by volume. Generally, the presence of this pore is a major drawback for electrical insulation applications. That is, the pores easily absorb moisture, and the insulating properties at the time of moisture absorption are reduced. However, in the production method of the present invention, the presence of the pores is a great advantage. This is because the mullite sprayed layer is formed by spraying a ceramic mainly composed of mullite on copper foil, and the woven prepreg is placed on this and hot-pressed, and the resin of the woven prepreg softens during hot pressing. Melts and impregnates the pores of the mullite sprayed layer. As a result, the pores of the mullite sprayed layer are sealed, and the problem of a decrease in insulating properties during moisture absorption is solved. Furthermore, the adhesiveness of the ceramic resin is a kind of material, and it is not good because of the different thermal expansion coefficients.
Since the resin impregnates the pores of the mullite sprayed layer during hot pressing, a strong adhesive force is obtained. The adhesive strength between the copper foil and the mullite sprayed layer is not satisfactory for use as a printed wiring board if it is still sprayed, but a strong adhesive strength is obtained by the resin reaching the copper foil surface through the mullite sprayed layer. Can be

As the woven fabric of the woven prepreg used in the present invention, the glass fiber woven fabric used for general laminates has its characteristics,
Although suitable in terms of price, other woven fabrics such as aramid fibers and quartz fibers can be used. The resin is preferably an epoxy resin or a polyimide resin used for a general laminate, but may be a phenol resin, a melamine resin, an unsaturated polyester resin, a vinyl ester resin, a fluorine resin, or the like.

(Function) The ceramic composite copper-clad laminate of the present invention has a mullite sprayed layer between a copper foil and a fiber-reinforced plastic layer. Due to the presence of a mullite layer with a low coefficient of thermal expansion (4.5 × 10 ^-6 / ° C), the coefficient of thermal expansion of the laminate is significantly lower than that of a conventional copper-clad laminate without a mullite layer, and the dimensional stability of the substrate Properties can be greatly improved. Further, since the mullite sprayed layer is softer than the alumina sprayed layer, drill abrasion during drilling is smaller than that in the case of using alumina, and therefore, the drill is less likely to be broken. In particular, a small diameter drill has a remarkable effect.

In addition, due to the presence of the ceramic mullite sprayed layer immediately below the copper foil, tracking resistance, arc resistance,
The copper foil peeling strength during heating is also excellent.

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

(Example) Mullite (show) was used on the roughened surface of an electrolytic copper foil 1 having a thickness of 18 μm (TSTO-18 μm, manufactured by Furukawa Circuit Foil) using a plasma spraying machine manufactured by Plasmadyne Co., Ltd., Plasmadyne System Model 3600-80R. Coat K80M, manufactured by Showa Denko) was sprayed to form a mullite sprayed layer 2 having a thickness of 100 μm.
Then, it was hot-pressed together with the glass fiber woven fabric epoxy resin prepreg 3 in the laminated structure shown in FIG. 1 to obtain a ceramic composite copper-clad laminate having a structure shown in FIG.

The coefficient of thermal expansion in the plane direction of the obtained ceramic composite copper-clad laminate was 7.8 × 10 ⁻⁶ ° C. ⁻¹ , and a four-layer plate press using a four-layer plate using this ceramic composite copper-clad laminate as an inner layer plate was used. The subsequent dimensional change was 0.004%. The thermal expansion coefficient in the surface direction of the ceramic composite copper-clad laminate having an alumina sprayed layer instead of the mullite sprayed layer was 8.3 × 10 ^-6 ° C ^-1 , and the dimensional change after pressing the four-layered plate was almost 0.003%. It was equivalent. In the conventional copper-clad laminate without the ceramic sprayed layer, the thermal expansion coefficient in the plane direction was 13.7 × 10 ⁻⁶ ° C. ⁻¹ , and the dimensional change after pressing the four-layer plate was 0.025%.

Next, when a hole was drilled with a carbide drill having a diameter of 0.35 mm using a ceramic composite copper-clad laminate having a mullite sprayed layer, the drill did not break even with 10,000 holes. On the other hand, in the ceramic composite copper clad laminate having the alumina sprayed layer, the drill was broken at 206 holes.

(Effects of the Invention) As described above, the ceramic composite copper-clad laminate obtained by the method of the present invention has a low coefficient of thermal expansion, tracking resistance, hot copper foil peeling strength, and the like. It is superior to a plate, and can greatly improve the drilling property, which is the biggest drawback of a ceramic composite copper-clad laminate using an alumina sprayed ceramic layer.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a laminated structure according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view showing the structure of the obtained ceramic composite copper-clad laminate. DESCRIPTION OF SYMBOLS 1 ... Electrolytic copper foil 2 ... Mullite sprayed layer 3 ... Glass fiber woven cloth epoxy resin prepreg 4 ... Glass cloth base epoxy resin

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-164530 (JP, A) JP-A-63-219562 (JP, A) JP-A-1-194384 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) H05K 1/03

Claims (6)

(57) [Claims] 1. A ceramic composite copper-clad laminate comprising a ceramic sprayed layer mainly composed of mullite provided between a copper foil and a glass fiber woven prepreg layer, which is hot-pressed. 2. The ceramic composite copper clad laminate according to claim 1, wherein the resin of the woven prepreg is an epoxy resin. 3. The ceramic composite copper clad laminate according to claim 1, wherein the resin of the woven prepreg is a polyimide resin. 4. A mullite-based ceramic sprayed layer is formed by spraying mullite-based ceramic on one side of a copper foil, and a glass fiber woven prepreg is placed in contact with the mullite-sprayed layer. A method for producing a composite copper-clad laminate, comprising hot-pressing the composite. 5. The method for producing a composite copper clad laminate according to claim 4, wherein the resin of the woven prepreg is an epoxy resin. 6. The method for producing a composite copper-clad laminate according to claim 4, wherein the resin of the woven prepreg is a polyimide resin.