JPS5848492A - Flexible printed circuit board and solder connecting method - 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 The present invention relates to a flexible printed wiring board and a method for connecting the printed wiring board to another printed wiring board.

Flexible printed wiring boards are often used as internal wiring for cameras, calculators, etc. in place of conventional individual wiring cables for electric wires. In that case, the flexible printed wiring board is
It is connected by soldering to a solid printed wiring board or the like that is installed inside the device. That is, as shown in FIGS. 1 and 2, this printed wiring board 1 includes wiring such as copper foil drawn in a predetermined pattern on a flexible base film 2 made of an electrically nonconducting material. Road 3
It has a through hole 4 in its terminal portion. Then, the remaining portion is covered with a protective coating 6, leaving a donut-shaped solder land 5 around the through hole 4. During actual soldering, the through hole 4 is positioned concentrically over the terminal portion 9 of the wiring path 8 formed on the component to be attached, for example, a solid printed wiring board 7, and the solder land 5 and The terminal portion 9 of the other party is soldered. However, since the solder land 5 is formed in a donut shape around the through hole 4, the solder ring 1o in a molten state goes around the entire circumference of the solder land 5, thereby blocking the through hole 4. Therefore, it is difficult to visually check whether the solder land 5 and the mating terminal part 9 are reliably soldered, and if the through hole 4 is relatively small, as shown in FIG.゜ may not be able to adhere to the mating terminal portion 9.

The present invention has been made in view of the above-mentioned drawbacks, and its object is to provide a flexible printed wiring board having a structure that allows the solder land to be reliably soldered to the mating terminal portion of the component to be mounted while visually observing the soldering process, □To provide a continuation method.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. Note that parts corresponding to those in FIG. 1 and FIG. 2 described above are given the same reference numerals.

FIG. 3 shows a plan view showing the main parts of the flexible printed wiring board according to the present invention.

As described in the explanation related to FIGS. 1 and 2, this flexible printed wiring board 11 includes a flexible base film 2 made of an electrically nonconductive material, and a predetermined pattern drawn on the flexible base film 2. a through hole 4 punched through the base film 2 at the center of the terminal portion forming a circular pattern of the wiring path 3; and a protection layer 3 formed on the base film 2 to protect the wiring path 3. However, in this invention, the coating 6 is not provided around the entire circumference of the through hole 4.
In a part of the area adjacent thereto, a solder land 12 is formed, for example, in a crescent shape as shown in the figure.

Note that the remaining portions other than this solder land 12 are covered with a protective film 6. The solder land 12 can be formed, for example, by peeling off the protective coating 6 around the through hole 4 to expose the conductor of the terminal portion of the wiring path 3.

Alternatively, the portion corresponding to the solder land 12 may be masked in advance by an appropriate means, and then the protective coating 6 may be applied to the remaining portion by, for example, a vapor deposition method.

Next, the operation and effects of the present invention will be explained with reference to FIGS. 4 and 5. In order to connect this flexible printed wiring board 11 to another printed wiring board 7 by soldering, mutual positioning is performed so that the through holes 4 are aligned with the mating terminal portions 9 of the cow, so that they are brought into close contact with each other. In that case, as shown in FIG. 4, the through hole 4 is slightly eccentric with respect to the mating terminal portion 9 as shown in FIG. It is preferable to place the The solder land 12 and the mating terminal part 9 are then soldered as shown in FIG. There is almost no risk of ice forming around the entire circumference of the mating terminal 9, and by arranging the through hole 4 eccentrically as described above, the molten solder ring 10 can adhere to the entire surface of the mating terminal 9. Even if it does, it will cause through hole 4
will not be blocked. Therefore, according to the present invention, the solder land 12 and the mating terminal part 9 can be reliably soldered connected while visually checking the so-called solder wetting condition on the mating terminal part 9 through the through hole 4. Thereby, the defective rate due to solder connections of flexible printed wiring boards can be significantly reduced, and high quality products can be obtained.

Furthermore, since the solder connection state can be easily confirmed, work efficiency itself can be improved compared to the conventional method. Further, since the solder connection is made in a part of the area adjacent to the through hole 4, the state of adhesion of the solder mass 10 to the mating terminal portion 9 can be checked by turning over the flexible printed wiring board 11. I will do my best to do it.

In the above embodiment, the solder land 12 is formed in a crescent shape, but the present invention is not limited to this shape.

[Brief explanation of the drawing]

FIG. 1 is a developed view showing a conventional example, FIG. 2 is a sectional view of the conventional example shown in FIG. Figure 4 is a diagram for explaining the soldering method for the printed wiring board shown in Figure 3, and Figure 5 is a sectional view taken along the line V-V in Figure 4, showing the soldering process. Inside, 2 is a base film, 3 is a wiring path, 4 is a through hole, 6 is a protective film, 7 is a printed wiring board to be attached, 9
10 is a solder lump, 11 is a flexible printed wiring board, and 12 is a solder land. Patent Applicant General Co., Ltd. Patent Attorney Taku Ohara Envelope Figure 1 Figure 3 Figure 5 Figure 2 Figure 4

Claims (1)

[Scope of Claims] (1) A flexible base film made of an electrically nonconducting material, a wiring path formed on the base film made of copper foil, etc., and passing the base film through the terminal portion of the wiring path. A through hole and 1. The through hole? A flexible printed wiring board having a protective film coated on the base film so as to leave a solder land on the surface, the solder land being formed in a part of the area adjacent to the through hole. A flexible printed wiring board characterized by: (2. In claim (1), the flexible printed wiring board is characterized in that the solder land is formed in a crescent shape having an inner arc that touches the circumference of the through hole. ( 3) A flexible base film made of an electrically nonconducting material, a wiring path made of copper foil or the like formed on the base film, a through hole penetrated through the base film at the terminal portion of the wiring path, and the transparent A mating terminal portion of a wiring path formed on another printed wiring board to which a flexible printed wiring board having a protective coating applied on the base film so as to leave solder land around the hole is attached. In the method of making a solder connection, the solder land is formed in a part of the area adjacent to the through hole, the through hole is superimposed on the mating terminal part of the printed wiring board to be attached, and the solder land is formed in a part of the area adjacent to the through hole. A solder connection for a flexible printed wiring board, characterized in that by soldering to the terminal portion of the attached printed wiring board through the through hole, solder is prevented from going around the entire circumference of the through hole. (4) In claim (3), the through hole is eccentric with respect to the mating terminal portion of the printed wiring board to be mounted so that the edge of the mating terminal portion of the mounted printed wiring board is exposed within the through hole. A method for soldering flexible printed wiring boards, which is characterized by stacking the printed wiring boards together.