JPS6113984B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a glass cloth-based copper-clad laminate, and its object is to provide a copper-clad laminate with excellent surface smoothness. Conventionally, in glass cloth-based copper-clad laminates, when a glass cloth base material with a unit weight exceeding 200 g/m ² is used, there is a drawback that the surface roughness of the copper-clad laminate becomes large. This invention improves this drawback. The glass cloth base copper clad laminate according to the present invention includes:
It is characterized by having the layered structure shown in Figure 1. That is, since it is a copper-clad laminate, the copper foil 1 is naturally arranged on the entire surface. A first layer 2 placed under the copper foil 1
is made of glass cloth base prepreg, the second layer 3 placed under the first layer 2 is made of glass paper base prepreg, and the core layer 4 placed under the second layer 3 is needle punched. It is made of a glass cloth base material prepreg. The glass cloth base prepreg 5 constituting the core layer 4 is different from the glass cloth base prepreg constituting the first layer 2 in that the base material is needle punched. different. The most suitable laminate varnish used in this invention is an epoxy resin varnish or an epoxy resin varnish in which an inorganic powder filler is dispersed. However, it is not limited to these. The copper foil is not particularly limited, and ordinary copper foil used for copper-clad laminates may be used as is. Note that the copper foil 1 does not necessarily have to be placed on both surfaces of the whole, and may be placed only on one of the surfaces. In this invention, the reason why the layer structure of the base portion (substrate) of the copper foil 1 is as described above is as follows. The reason why a glass cloth base material is used as the base material of the first layer 2, that is, the surface layer, is to prevent the chemicals used for etching from remaining on the substrate after etching and removing the copper foil. When glass paper or needle-punched glass cloth is used as the base material for the surface layer, the glass threads protrude from the surface, so when the copper foil is removed by etching, the chemicals used for etching must be completely washed away. The disadvantage is that it is difficult to remove and remains on the substrate. The reason why a prepreg made of glass paper as a base material is used for the second layer 3 is to increase interlayer adhesion and improve the surface smoothness of the copper-clad laminate. If the surface smoothness of the copper-clad laminate is poor, when it is processed into a printed wiring board, the adhesion of the photosensitive film is poor, causing problems such as the inability to obtain thin circuits. Using a needle-punched glass cloth base material as the base material for the core layer 4, which consists of the third and subsequent layers, increases the amount of resin adhered,
This is to improve the surface smoothness of the copper-clad laminate. When using a glass cloth base material that is not needle-punched, increasing the amount of resin deposited tends to cause slipping during lamination formation, which has the disadvantage of significantly reducing the yield of copper-clad laminates. If the amount of resin deposited is small, unevenness due to the weaving of the glass cloth will appear on the surface of the copper-clad laminate, making it impossible to obtain good surface smoothness. When the core layer 4 is made of glass paper base prepreg, there is a drawback that warpage increases when the copper-clad laminate is processed into a printed wiring board. The glass cloth base copper clad laminate according to the present invention includes:
In this way, since the glass paper base prepreg is used under the first layer, it is possible to improve the interlayer adhesion and surface smoothness, and the base of the glass cloth base prepreg that makes up the core layer can be improved. Since the material is needle punched, the resin content of this prepreg can be increased and the surface smoothness can be further improved. Next, the advantages of the present invention will be clarified by describing Examples along with Comparative Examples. Example A copper-clad laminate A having the layer structure shown in FIG. 2 was obtained by using a surface-treated copper foil 1 having a thickness of 18 microns. The epoxy resin varnish used was the varnish used for ordinary glass cloth-based epoxy resin laminates. As the glass cloth base material of the surface layer (first layer) 2, a plain weave glass cloth with a unit weight of 204 g/m ² was used, and the amount of resin attached was 45%. As the glass paper base material for the second layer 3, one having a unit weight of 60 g/m ² was used, and the amount of resin attached was 65%. Core layer (3
Glass cloth base prepreg 5 used in ply) 4 was a plain woven glass cloth with a unit weight of 240 g/m ² that was needle punched, and the amount of resin attached was 55%. Comparative Example 1 Using the same copper foil and epoxy resin varnish as in Example, the copper foil 1 was placed on the surface as shown in FIG. 3, and the entire board from the surface layer to the core layer (8 plies) 6 A copper-clad laminate B consisting of the glass cloth base material prepreg 7 was obtained. Glass cloth base material prepreg 7 uses plain woven glass cloth with a unit weight of 204 g/m ² as a base material, and has a resin adhesion amount of 45%. Comparative Example 2 Using the same copper foil and epoxy resin varnish as in the example, the copper foil 1 was placed on the surface as shown in FIG. A copper-clad laminate C was obtained, in which the portion (10 plies) 8 from the second layer to the core layer was made of the same glass paper base prepreg 9 as used for the second layer in the example. Comparative Example 3 Using the same copper foil and epoxy resin varnish as in the example, the copper foil 1 was placed on the surface as shown in FIG. A copper-clad laminate D is made of prepreg, and the portion (4 plies) 10 from the second layer to the core layer is made of glass cloth base material prepreg 5 subjected to the same needle punching process as used for the core layer in the example. Obtained. Comparative Example 4 Using the same copper foil and epoxy resin varnish as in the example, the copper foil 1 was placed on the surface as shown in FIG. A copper-clad laminate E was obtained, in which the portion (5 plies) from the second layer to the core layer was made of a glass cloth base material prepreg 12 that was not subjected to needle punching. The glass cloth base material prepreg 12 uses plain woven glass cloth with a unit weight of 240 g/m ² that has not been needle punched as a base material,
The amount of resin attached is increased to 55%. Table 1 summarizes the performance of the copper-clad laminates obtained in Examples and Comparative Examples.

[Table] Copper-clad laminate C has good surface smoothness, but since the core layer is made of glass paper base prepreg,
The warpage is large. In the copper-clad laminate E, slipping occurred during molding because the glass cloth prepreg base material constituting the core layer was not punched and the amount of resin adhered was increased. As can be seen from this table, using glass paper base prepreg for the second layer and glass cloth base prepreg that has been needle-punched to increase the amount of resin for the subsequent layers is effective for copper-clad laminates. It is extremely effective in improving the surface smoothness of the plate.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the layer structure of a glass cloth-based copper-clad laminate according to the present invention, FIG. 2 is an explanatory diagram of the layer structure in an example of this invention, and FIGS. 3 to 6 are comparative example 4. It is an explanatory view of each layer composition in a seed. 1... Copper foil, 2... First layer, 3... Second layer, 4
...core layer.

Claims (1)

[Claims] 1 Copper foil is arranged on the surface, the first layer arranged under the copper foil consists of a glass cloth base prepreg, the second layer arranged under the first layer consists of a glass paper base prepreg, A glass cloth-based copper-clad laminate, characterized in that a core layer disposed under the second layer is made of a glass cloth-based prepreg subjected to needle punching.