JPH07131140A - Printed board - Google Patents

Abstract

PURPOSE:To prevent shortcircuit between a part to be mounted and a printed board due to excessive solder, by forming both of insertion part mounting holes with through hole plating and those without through hole plating. CONSTITUTION:Since the periphery of a printed board 5, a flexible printed board in particular, is coated with a cover film, in general, solder resist is not placed thereon. When a small-pitch part 7 is mounted, however, it is impossible to coat the entire circumference of lands with a cover film because of its small distance between pins. If excessive solder is fed in this case, the solder overflows the lands between a printed board 5 and the mounted part 7 at the pins 2, 4 with through hole plate. When there are pins 3 provided only with lands 8 and with no through hole plating 6, the solder, if it is too much, is not lifted to the part mounting level and thus no short circuit due to solder occurs. This makes it possible to increase the soldering pitches and thus prevent short circuits.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a through hole for mounting a narrow pitch insert part in a printed board for mounting an insert part.

[0002]

2. Description of the Related Art In the prior art, Japanese Patent Laid-Open No. 64-9687
As described in, the shape of the land is changed between the component mounting surface side and the soldering surface side to prevent solder short circuit.

[0003]

When mounting a narrow-pitch insert component on a printed board of a two-layer board or a multilayer board without solder resist, it is possible to correct a short circuit on the solder side when excessive solder is supplied. However, it is difficult to correct a short circuit on the component mounting surface side. Even with the conventional technology, it is possible to prevent a short circuit on the component mounting surface side by making the land on the component mounting surface side smaller, but for objects with a narrower component pin pitch, there is a problem that short circuit occurs even if the shape of the land is changed. there were.

[0004]

In order to achieve the above object, a narrow-pitch component is formed by alternately using a place where through-hole plating is provided and a place where land is not formed in the component mounting insertion hole. At the time of mounting, even if the supply of solder becomes excessive, there is no short circuit.

[0005]

[Function] In the through-hole plating hole, the solder goes up to the land on the component mounting surface. In the non-through hole, the solder is attached only to the land on the solder surface, and the solder does not rise to the component mounting surface. Therefore, by alternately using the through-hole-plated holes and the holes that do not, the short circuit (solder bridge) between the mounted component and the printed board due to excessive solder is prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Printed board 5 In particular, a flexible printed board (hereinafter referred to as an FPC) does not have a solder resist, because it covers the land with a cover film. However, when the narrow pitch component 7 (for example, 1.27 pitch connector) is mounted, since the pin interval is small, the cover film cannot be covered over the entire land. At this time, if the solder is excessively supplied by hand or the like, the pins 2 and 4 having the through-hole plating 6 will overflow from the land between the printed board 5 and the mounting component 7 and the solder will flow out. Since the pin 3 does not have the through-hole plating 6 and has only the land 8, even if the solder is excessive, the solder does not rise to the component mounting surface and there is no short circuit due to the solder. In the prior art, there is a possibility that the insulation distance between the pins may not be secured due to the solder flowing out even if a short circuit occurs between the pins 2 and 3 as shown in FIG. was there.

[0007]

According to the prior art, as shown in FIG. 2, an excessive supply of solder causes a short circuit (solder bridge) on the component mounting surface side.
There has occurred. In the present invention, by alternately providing the lands on the component mounting surface side, the soldering pitch is increased,
Short circuit (solder bridge) can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

 1 ... Solder, 2 ... Component insertion pin, 3 ... Component insertion pin, 4 ... Component insertion pin, 5 ... Printed board, 6 ... Through hole plating, 7 ... Narrow pitch insertion component.

Front Page Continuation (72) Inventor Hideaki Mizuno 1 Ikegami, Haruoka-cho, Owariasahi-shi, Aichi Hitachi Ltd. Office Systems Division

Claims (1)

[Claims] 1. A printed circuit board characterized in that a hole for mounting an insertion part is mixed with a hole provided with through-hole plating and a hole not provided.