JPH03131086A - Flexible board - Google Patents

Abstract

PURPOSE:To improve etching properties of a copper foil of a fine pattern and to reduce the size of a pattern pitch by reducing the thickness of the foil by half etching, etc. CONSTITUTION:A copper pattern 2 is connected from inner leads 4 of an IC hole 6 to outer leads 5 through a slit hole 7. In this case, after the foil 2 is laminated on a base film 1, it is partly half-etched to form a structure having a thin part 2a. The foil which is partly reduced in thickness has satisfactory etching properties as compared with the thick part 2 of the other foil to reduce the side etching amounts of the patters 2a, 3a and to increase a size F of the gap between the patterns. Accordingly, a pitch size between the patterns and the size of a part D can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flexible substrate in which copper foil is laminated on a film.

[Conventional technology] In the conventional technology, the thickness of the copper foil is uniform over the entire etching surface, and the amount of side etch of the copper foil becomes thick during patterning etching, which results in a large pattern pitch dimension. A schematic diagram of the main parts of the conventional substrate pattern is shown in FIG. 2. FIG. 2 (α) is a plan view of the conventional example, and FIG. FIG.
It is connected to the outer lead part 5 through the slit hole 7. In particular, the pattern tends to concentrate between the cut hole 6 and the slit hole 7, and the space in the base film 1 is also small.

FIG. 2 CC) is a sectional view taken along line B-B' in FIG. 2 (α).

The pitch dimension of copper patterns 2 and 3 is indicated by 0, and the pattern gap dimension is indicated by E. When the side etch dimension of pattern 2.3 is large, the gear E dimension becomes narrow (so the pitch C dimension had to be increased).

[Problems to be Solved by the Invention] However, with the above-mentioned conventional technology, when trying to manufacture a flexible board that is compatible with the miniaturization and multi-bin IC, there is little space for arranging lead routing patterns. The patterns and pitches became so fine that it was impossible to ensure proper pattern width and gaps when etching the copper foil. Therefore, the present invention aims to solve this problem between layers, and its purpose is to improve the etching properties of copper foil and reduce the pattern pitch size (by reducing the pattern pitch size).
The purpose of the present invention is to provide a finely patterned flexible substrate that can cope with the increase in fineness and multi-pin design.

[Means for Solving the Problems] The flexible substrate of the present invention is a 7-lexiple substrate in which copper foil is laminated on a film, and is characterized in that the copper foil in the fine pattern portion is thinned by half-etching or the like.

[Effects] According to the above structure, the etching performance of the thin part of the copper foil is greatly improved, the amount of side etching of the copper foil pattern is improved, and the pitch between the leads can be reduced. , the number of patterns can be increased within a limited range.

[Example] FIG. 1 is a schematic diagram of the main parts of a 7-lexiple board pattern according to the present invention. Figure 1 (α) is a plan view, Figure 1 Cb)
is a cross-sectional view taken along line ao' in FIG. 1(α), and FIG. 1(C) is a cross-sectional view taken along line b-bt in FIG. 1(α).

The copper pattern 2 is connected from the inner lead part 4 of the ICC 60 to the outer lead part 5 through the slit hole 7. At this time, after the copper foil 2 is laminated on the base film 1, the thinned portion 2 (
It has a structure with L. This partially thinned copper foil part has better etching properties than the other thicker parts 2 of the copper foil. The feature of the present invention is that the pattern gap dimension F part can be increased, so the pattern pitch dimension and the dimension D part can be reduced.
This is simply a thinner copper foil in the fine pattern portion, and there are no particular limitations on the size, thickness, shape, etc. of the substrate.

[Effects of the Invention] As described above, according to the present invention, by thinly etching a part of the copper foil, the side etch amount of the copper pattern can be improved. Compared to etching a thicker copper foil, the lead pitch dimension can be reduced by 30%, making it possible to respond to finer and more numerous bins.

[Brief explanation of the drawing]

FIG. 1 (α) is a plan view showing an embodiment of the flexible 7-pull board of the present invention. FIG. 1(A) is a sectional view taken along line C-c' in FIG. 1(α). FIG. 1(C) is a sectional view taken along line DD' in FIG. 1(α). FIG. 2(α) is a plan view showing an example of a conventional flexible substrate. FIG. 2 Ch) is a sectional view taken along line AA' in FIG. 2 (α). FIG. 2(C) is a sectional view taken along line BB' in FIG. 2(α). 1...Flexible paste material 2-3...Copper lead pattern 2α-3a...Half-etched copper lead pattern 4...Copper lead pattern inner Lead part 5... Copper lead pattern Outer lead part 6... Machining C hole 7... Slit hole or more

Claims (1)

[Claims] A flexible board in which copper foil is laminated on a film, and is characterized in that the copper foil in the fine pattern part is thinned by half-etching or the like.