JP2009164342A - Flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible wiring board having a test pad capable of surely performing an electric inspection. <P>SOLUTION: A test pad part TP provided for inspecting a short circuit and disconnection among wiring L is formed in the shape of being projected upwards more than the surrounding wirings L. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flexible printed circuit board, and more particularly to a test pad of a TAB tape.

  The TAB tape has a tape width of 35 mm, 48 mm, and 70 mm, and is manufactured in a long shape. That is, an adhesive is laminated on the film having the above width, opened at a desired position using a mold, and a copper foil is laminated. A photoresist is applied to this, and a desired pattern is exposed and developed to form a photoresist pattern. This is etched to dissolve unnecessary portions of copper, and the photoresist is removed to form copper wiring (see, for example, Patent Document 1). This is mainly subjected to tin plating, and a solder resist is formed by screen printing. Recently, a substrate is also used in which a base conductive layer is formed on a film by sputtering or the like and then copper plating is performed without using an adhesive.

These products are shipped after all electrical inspections such as short-circuiting and disconnection of wiring are performed. In the electrical inspection, a probe in which probe pins are arranged in the same manner as a test pad is used, a voltage is applied by directly applying the probe pin to the test pad, and the presence or absence of a short circuit with an adjacent wiring is inspected (for example, patent) Reference 2). As shown in FIG. 3, the probe pin P has a generally pointed tip shape, and has a structure that is contracted by a spring when pressure is applied to the tip, for example, when contacting the test pad TP. For this reason, it has a structure that can absorb variations in the height direction of the probe pins P and variations in the height of the wiring and the test stage.
JP 2003-318233 A JP-A-10-223702

Usually, the test pad is provided in a portion that is not used in the final product, and after the electrical test is completed, only the necessary portion excluding the test pad is punched out by the mold.
On the other hand, in order to reduce the product cost, it is required to reduce the product area per piece, and there is a demand to reduce the area of a test pad that is not used as a product as much as possible. For this reason, products with a test pad width of 100 μm or less have come out.
Careful alignment work is required to apply the probe pin to the test pad of this size, which takes time. Further, the alignment accuracy of the apparatus is limited to about ± 50 μm, and the accuracy of the probe pin is limited to about ± 30 μm with respect to the design value, which makes alignment difficult. Furthermore, in order to further increase productivity, an apparatus capable of simultaneously performing two inspections at a time has been developed, and it has become increasingly difficult to align the probe pin with the test pad of the product.

  Further, as shown in FIG. 3B, when the probe pin P comes into contact with the end of the test pad TP and pressure is applied, the probe pin P is displaced from above the test pad TP and falls between the wirings. For this reason, although there is no short circuit of the wiring in the product itself, the adjacent wiring and the probe pin are in contact with each other, so that it is determined as a short circuit in the inspection. Further, when the probe pin is displaced and falls between the wirings, the pattern is scratched, and at that time, a metal foreign object is generated, which may cause a short circuit between the patterns.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a flexible wiring board having a test pad capable of reliably performing an electrical test. .

  In order to achieve the above object, the flexible printed wiring board according to the present invention is characterized in that a test pad portion provided for inspecting a short circuit or a disconnection between wirings has a shape protruding above the surrounding wiring. And

  According to the present invention, the test pad portion is formed by half-etching the surrounding wiring.

  According to the present invention, an electrical inspection of a flexible substrate can be carried out stably without erroneous detection.

Hereinafter, embodiments of the present invention will be described based on illustrated examples.
FIG. 1 is a plan view of a test pad portion of a flexible printed wiring board according to the present invention, and FIG. 2 is a schematic sectional view taken along the arrow in FIG.

  Electrical inspections such as short-circuiting and disconnection of wiring of this type of flexible printed wiring board are performed using probe pins P having a flat tip or an arc shape. In this electrical inspection, the product and the stage are first aligned, and then a probe in which probe pins P are arranged so as to correspond to the position of the test pad TP of the product comes down from above the product (FIG. 2). (A)) The tip of the probe pin P contacts the test pad TP (FIG. 2B).

  In the present invention, since the test pad TP is formed higher than the surrounding wiring L, even if the position of the probe pin P is slightly shifted from the test pad TP, the probe pin having a flat tip is provided. P contacts only the test pad TP and does not contact the adjacent wiring L.

EXAMPLE A TAB tape of the present invention was produced by the following steps. First, a 12 mm thick adhesive (Toray # 7100) was laminated to a polyimide film (UPILEX-S made by Ube Industries) with a thickness of 35 mm and a thickness of 75 μm, a device hole was opened using a mold, and a 18 μm thick copper foil ( Mitsui Kinzoku FQ-VLP) was laminated. A photoresist was applied thereto, and a wiring pattern having a test pad width of 85 μm was exposed and developed to form a photoresist pattern. After etching this and dissolving unnecessary copper, only the portion of the wiring L around the test pad TP where the wiring thickness was thinner than the test pad was exposed and developed. This was etched so that the wiring around the test pad to be thinned had a desired thickness, and the photoresist was removed to form a copper wiring. This was subjected to tin plating, and a solder resist layer was formed by screen printing.
When this was electrically inspected, there was no problem due to false detection.

  On the other hand, when an electrical test was performed by a normal method, there was an error of 10 pcs in 1000 pcs.

It is a top view of the test pad part of the flexible printed wiring board concerning the present invention. It is a cross-sectional schematic diagram which follows the arrow of FIG. It is a cross-sectional schematic diagram corresponding to FIG. 2 of the test pad part in the conventional flexible printed wiring board.

Explanation of symbols

P Probe pin TP Test pad L Wiring

Claims (2)

  A flexible printed wiring board characterized in that a test pad portion provided for inspecting a short circuit or a disconnection between wirings protrudes upward from surrounding wirings.   The flexible printed wiring board according to claim 1, wherein the test pad portion is formed by half-etching surrounding wiring.

Images