JPS603092B2 - Etching method for resin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for etching a resin film.

The conventional etching method for resin films consists of the first step.
As shown in Figure A, a metal film 2 is selectively formed on a resin film 1 using a photoresist, and then etched holes 3 are formed by dipping in an etching solution as shown in Figure B.

4 is an adhesive layer.

This conventional etching method is '1' - Generally, the etching speed is slow, so the etching time is long and efficiency is low. Also, when it is desired to form a vertical take-out hole in a multilayer wiring resin film, the depth of the etched hole is the same in one etching process, so etching can be repeated several times to obtain etched holes with different depths. Because of this, he had a problem with his work efficiency, such as poor work efficiency. The present invention has been proposed in light of the above-mentioned conventional method, and it is an object of the present invention to provide an efficient etching method. The etching method according to the present invention will be explained below with reference to the drawings.

FIG. 2 shows a first embodiment of the present invention. In FIG. 2A, reference numeral 11 denotes a resin film to be etched, which is usually made of polyimide, polyester, or the like. 15 is an adhesive layer.

Here, the following explanation will be given using polyimide having a thickness of about 10 to 125 mm as the resin film 11 and FEP resin as the adhesive 15. Now, as shown in figure B, resin film 1
1 and a substrate 14 such as a film or plate having a different coefficient of expansion. This adhesion is carried out by pressing the resin film 11 and the substrate 15 in the direction of the arrow with a force of about 30 mm. As the substrate 14, iron, aluminum, stainless steel, silicon, etc., which have a different coefficient of expansion from the resin film 11, can be used. At the temperature at which the resin film 11 and the substrate 14 are bonded together (approximately 30°C and 0°C), no stress is applied to them, but the etching temperature at which the resin film 11 is etched is approximately 80°C, and there is a difference in expansion coefficient between the two. The stress caused by In other words, as the bonding temperature (approximately 30 mm) is lowered to the etching temperature (approximately 8 mm), the expansion coefficient of the substrate 14 becomes 4 mm lower than that of the resin film 11.
Sometimes "tensile stress is generated in the resin film 11,
Conversely, when the expansion coefficient of the substrate 14 is larger than that of the resin film 11, compressive stress is generated in the film 11.
In FIG. 1C, reference numeral 12 denotes a metal film which is selectively partially removed using photoresist after being subjected to a treatment such as photoresist or vapor deposition plating. Figure D shows a cross section of the shape after etching, and an alkaline solution such as NaOH is suitable as the etching solution. Now, when the resin film 11 was etched using an etching solution with a concentration of 50% NaOH without bonding the substrate 14, the etching rate was 2 μm/min.
200 mounds thick silicon (expansion coefficient 2 x 10-6
/c), and when this was adhered to the resin film 11 (polyimide expansion coefficient: 16 to 20 x 10-6/°C) and etched, an etching rate of 10 France/min was obtained. In other words, if etching is performed with tensile stress generated in the resin film 11, the etching speed will be increased. Of course, this etching speed depends on the thickness of the resin film 11 and the substrate 1.
Not only does the etching rate vary significantly depending on the thickness of the substrate 14, etc., but also the etching rate is faster as the expansion coefficient of the resin film 11 is smaller than that of the substrate 14. Therefore, the etching rate can be changed by freely selecting the expansion coefficient and thickness of the substrate 14. You can. FIG. 3 shows a resin film 11 in a second embodiment.
A substrate 14 is selectively bonded to the substrate.

Assuming that the expansion coefficient of the substrate 14 is smaller than that of the resin film 11, as shown in the figure, tensile stress is generated in the portion of the resin film 11 corresponding to the substrate 14, so the etching speed is fast and deep etching holes 13 are formed. You can get it, but
The etching rate of the non-corresponding portions of the substrate 14 is slow, and shallow etching holes 13' are obtained. By selectively bonding the substrate 14 as in this embodiment, etching holes with different depths can be obtained in a single etching process. In this case, if the substrate 14 has a complicated and fine array of etching holes 13, it is more efficient to form a pattern in advance by punching or chemical etching and then bond it to the resin film 11. As described above, even if the pattern arrangement of the etching holes becomes complicated or fine as in the case of multilayer wiring, the efficiency is greatly improved according to this embodiment. FIG. 4 shows a third embodiment in which substrates 14a, 14b, and 14c having different coefficients of expansion are bonded to a resin film 11.

The expansion coefficients of the substrates 14a to 14c are Qa, qb, and
Qc, and when Qa<Qb<qc, each substrate 1
The depths of etching holes 13a to 13c corresponding to holes 4a to 14c are different as shown in the figure. In this case, three or more etching holes with different depths can be formed. Figure 5A,
B and C are fourth embodiments, in which a substrate 14 having a smaller expansion coefficient than the resin film 11 is adhered to the back surface of the portion of the resin film 11 to be etched, and the portion is crushed in an etching solution for etching.

In this case, the entire surface of the resin film 11 is etched, but since the etching speed of the part corresponding to the part to which the substrate 14 is bonded is extremely fast, it is possible to obtain substantially the same effect as selective etching. . In the case of this embodiment, since non-uniform etching occurs around the etching hole 13, high precision cannot be required. However, it can be applied to etching holes with large diameters. In the above embodiment, the case where tensile stress is applied to the resin film 11 has been described, but conversely, when compressive stress is applied, the etching speed becomes slightly slower than when the substrate 14 is not bonded. More efficient etching can be achieved by appropriately combining stresses.

As described above, according to the present invention, since the etching rate can be changed, the working efficiency is greatly improved, and its industrial value is great.

[Brief explanation of drawings]

Figures 1A and B are etching process diagrams for a secondary resin film, Figures 2A to D are etching process diagrams for the same film according to the first embodiment of the present invention, and Figures 3 and 4 are diagrams for the etching process of the same film according to the first embodiment of the present invention. 2. A cross-sectional view of the same etching state of the third embodiment, and FIGS. 5A to 5C are process diagrams of the fourth embodiment of the present invention. 111...Resin film, 12...Metal coating, 13...Etching hole, 14...Substrate, 15
...Bag adhesive. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. After bonding a substrate having a different coefficient of expansion to one main surface of a resin film via a thermoplastic adhesive layer, the other main surface of the resin film is selectively chemically bonded. A resin film etching method characterized by etching. 2. The method of etching a resin film according to claim 1, wherein the expansion coefficient of the resin film is larger than that of the substrate, and the plasticity temperature of the adhesive layer is higher than the etching temperature. 3. A method for etching a resin film according to claim 1 or 2, characterized in that the substrate is divided into a plurality of parts, and the divided substrates are selectively adhered to the resin film. 4. The resin film etching method according to claim 3, wherein each of the divided substrates has an expansion coefficient as required.