JPS62108596A - Inner layer display method of multilayer printed board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] When producing a multilayer printed board by laminating an inner layer with a pattern and an outer layer without a pattern and bonding them by thermocompression, a figure number symbol pattern is formed on the inner layer. By displaying the figure number symbol pattern on the copper foil surface of the outer layer,
Prevent false patterns from being formed on the outer layer.

[Industrial application field]

The present invention relates to a method for displaying inner layers of a multilayer printed board.

Multilayer printed boards are widely used in electronic devices, and multilayer printed boards must be formed with a predetermined combination of inner and outer layer patterns.

[Conventional technology]

The conventional manufacturing procedure for multilayer printed circuit boards is to first leave edge material of the desired width around the four peripheries of a laminated board with copper foil adhered to the surface, and then etch a predetermined pattern within the frame of the edge material. to produce the inner layer.

Next, a plurality of inner layers are laminated with prepreg interposed therebetween, and a laminated board serving as an outer layer with no pattern formed on the copper foil surface is placed on both sides of the inner layer with prepreg interposed therebetween. Laminate the layers.

In this state, while heating to a predetermined temperature, a predetermined pressure is applied with a press to fuse the prepreg as an adhesive sheet between each layer, and the inner and outer layers are fixed and integrated to produce a printed board base material.

Next, the outer layer pattern is formed by etching the inside of the edges of the outer layer copper foil on both surfaces of the printed board base material, which has a predetermined pattern formed only on the inner layer, as desired. .

Thereafter, the edge material is cut to produce a multilayer printed board.

[Problem that the invention seeks to solve]

However, in the conventional multilayer printed board manufacturing method described above, when forming the outer layer pattern, the surface of the printed board base material is uniformly covered with copper foil, and it is difficult to determine what kind of pattern is formed on the inner layer. Can not do it.

Therefore, there is a problem that there is a possibility that an erroneous pattern different from the predetermined outer layer pattern may be formed.

[Means for solving problems]

In order to solve the above-mentioned problems of the conventional art, the present invention, as shown in FIG. 1 to FIG. Symbol pattern 4a
The inner and outer layers are laminated via the prepreg 7, and the printed board base material 1 is formed so that stronger pressure is applied to the surface area of the outer layer 5 corresponding to the figure number symbol pattern 4a than to other areas. By thermocompression bonding, the characters of the figure number symbol pattern 4a are made to stand out on the copper foil surface of the outer layer 5.

[Effect]

Generally, during thermocompression bonding to produce the printed board base material 1, a portion of the resin of the semi-cured prepreg 7 flows out around the printed board base material.

Therefore, if stronger pressure is applied to the surface area of the outer layer 5 corresponding to the figure number symbol pattern 4a than other areas, the thickness of the prepreg 7 will be smaller in the area to which this pressure is applied than in other areas. Become thin. For this reason, figure number symbol pattern 4
Only the letter a is convex.

The convex portions of the letters push up the copper foil of the outer layer 5, causing the figure number symbol to stand out on the surface of the copper foil of the outer layer.

That is, the figure number symbol can be visually recognized from the outside, and there is no fear of forming an incorrect outer layer pattern by etching.

〔Example〕

The present invention will be specifically explained below with reference to illustrated examples.

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is a sectional view of the thermocompression bonding process of the invention, Fig. 3 is a sectional view of an embodiment of the invention, and Fig. 4 is an embodiment of the invention. FIG. 5 is a plan view of the crimp plate of the embodiment of the present invention, and FIG. 5 is a side sectional view of the crimp plate of the embodiment of the present invention.

In FIGS. 72, 4, and 5, the lower crimp plate 12
The printed board base material l laminated on the upper surface includes, from below, an outer layer 5a having a copper foil surface on the lower surface, a prepreg 7, an inner layer 6a having a desired pattern formed within the frame of the edge material, a prepreg 7, and an edge. An inner layer 6 in which a figure number symbol pattern 4a is formed on the copper foil portion of the edge material, and a desired pattern is formed within the frame of the edge material.
, prepreg 7, and outer layer 5 having a copper foil surface on the upper surface are laminated in this order.

Then, the upper pressure bonding plate 10 is placed on the upper surface of the printed board base material l.

The upper pressure bonding plate 10 has a rectangular plate shape that is larger than the printed board base material 1, and the lower surface that presses the printed board base material 1 is flat.

However, the outer layer 5 facing the area of the figure number symbol pattern 4a
The pressure contact area has a thickness h of 200 μm to 300 μm.
A rectangular metal piece 11 of m is attached. Note that the upper surface of the lower pressure bonding plate 12 is flat.

As mentioned above, when the printed board base material 1 is laminated between the lower pressure bonding plate 12 and the upper pressure bonding plate 10 and is pressed with a press while heating, the prepreg 7 between each layer becomes an adhesive sheet and is fused. Then, all the inner and outer layers are fixed together to produce the printed board base material 1.

At this time, as shown in FIGS. 1 and 3, the upper pressure bonding plate 10
The metal piece 11 provided on the bottom surface of the figure number symbol pattern 4
The edge material 3 portion of the outer layer 5 corresponding to a is pressed with a stronger pressure than other surfaces.

Therefore, the prepreg 7 in the area where this pressure is applied
The resin flows out around the printed board base material 1 in a larger amount than in other areas. Therefore, the thickness of the prepreg 7 becomes thinner, and only the characters of the figure number symbol pattern 4a formed on the copper foil surface of the inner layer 6 become convex than the surroundings.

And the convex part of this letter is the outer layer 5! 1iIffa is pushed up, and the figure number symbol 4 oozes out on the copper foil surface of the outer layer 5.

That is, since the figure number symbol 4 can be visually recognized from the outside, there is no possibility that an incorrect outer layer pattern will be formed on the outer layers 5, 5a.

After forming the outer layer pattern of the printed board base material 1, the edge material 3 portion is cut to complete the multilayer printed board 2.

〔Effect of the invention〕

As explained above, the present invention allows the figure number symbol pattern provided on the inner layer of a multilayer printed board to sludge out to the outer layer.

[Brief explanation of drawings]

Fig. 1 is a plan view of an embodiment of the present invention, Fig. 2 is a sectional view of the thermocompression bonding process of the invention, Fig. 3 is a sectional view of an embodiment of the invention, and Fig. 4 is an embodiment of the invention. FIG. 5 is a plan view of the crimp plate of the embodiment of the present invention, and FIG. 5 is a side sectional view of the crimp plate of the embodiment of the present invention. In the figure, 1 is the printed board base material, 2 is the multilayer printed board, 3 is the edge material, 4 is the drawing number symbol, 4a is the drawing number symbol pattern, 5.5a is the outer layer, 6.6a is the inner layer, 7 is prepreg , 10 is an upper crimp plate, 11 is a metal piece, and 12 is a lower crimp plate.

Claims (1)

[Claims] The figure number symbol pattern (4a) of the multilayer printed board (2) is printed on the copper foil portion of the edge material portion of the inner layer (6) adjacent to the outer layer (5).
The inner and outer layers are laminated via the prepreg (7), and a stronger pressure is applied to the surface area of the outer layer (5) corresponding to the figure number symbol pattern (4a) than to other areas. An inner layer display of a multilayer printed board, characterized in that the printed board base material (1) is bonded under heat and pressure, and the characters of the figure number symbol pattern (4a) are embossed on the copper foil surface of the outer layer (5). Method.