JPS5856491A - Printed circuit board - 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 printed circuit board for mounting multi-terminal components, for example flat, (cage type I, SI, etc.).

When mounting a multi-terminal electronic component, such as a flat package LSI, which consists of a component body made of a molded part and a large number of terminals protruding around the component body, to a printed circuit board, laser beam, infrared rays or A method is used in which a spot heat source such as hot air is continuously scanned to solder the terminals in a soldering pattern. In this method, the spot heat source passes continuously along the pattern for soldering placed at a predetermined interval, so that soldering that does not require heat source irradiation can be done not only between patterns, but also on electronic components without terminals. The spot heat source will be irradiated to the corner of the In this case, the soldering process does not cause burnt marks on the printed circuit board between the patterns due to heat absorption by the patterns, but there is a disadvantage that burnt marks occur in areas other than these areas where the spot heat source passes. Therefore, in order to prevent burning, attempts have been made to provide a sacrificial pattern that is not directly related to soldering on the printed circuit board, and to absorb heat using this sacrificial pattern, but simply providing a sacrificial pattern is not reliable. lack of sex.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a soldering pattern and a discarding pattern on the board body, and to set the distance between these two patterns in a constant relationship. An object of the present invention is to provide a printed circuit board that can reliably prevent browning of the board body.

The present invention will be described below based on an embodiment shown in the drawings. 1st rI! 1 to 1 in Fig. 3 shows a multi-terminal electronic component such as a flat package type LSI. Many terminals 3・
It is formed from... On the other hand, 4 is the board body of the printed wiring board, and the electronic component mounting portion 6 on this surface has a soldering pattern 6... and an L-shaped discard pattern 7...
・ is provided. The above soldering is for pattern 6...
are arranged at predetermined intervals in correspondence with each terminal 3... of the multi-terminal electronic component 1, and the discarded patterns 7... are placed near the corner portions 1a... of the multi-terminal electronic component 1. It is provided. . Therefore, the multi-terminal electronic component 1 is connected to the board body 4.
By positioning the terminals 3 in the electronic component mounting portion 5, each terminal 3 comes into contact with the soldering pattern 6.

In addition, the above soldering pattern 6...the distance between them is 11, the width of the same pattern 6... is T, and the above discarding pattern 7 and the soldering at a close position are the same as the use pattern 6. If the distance between the openings is t, then O≦t,≦2(t,−T
) is set in the relationship.

Therefore, when mounting the multi-terminal electronic component 1 on the board body 4, a spot heat source 8 such as a laser beam, infrared rays, or hot air is irradiated, and the terminals 3...
When continuously scanning along the lines, each terminal 3... is heated by thermal energy from the spot heat source 8, and the soldering pattern 6... is fixed. At this time, the soldering patterns 6 and 6, the space between the patterns 6 and the disposable pattern 1, and the upper surface of the temporary pattern 7 also receive heat energy from the spot heat source 8, but the spacing between these is determined by the above formula. Since a satisfactory distance is set, heat is absorbed by the solder pattern 6 and the waste pattern 2 during soldering, and the board body 4 is not browned.

Here, the inventor's experimental results will be described.

First, as shown in FIG. 4, the laser beam L is continuously scanned as shown by the solid line arrow while changing the distance T between the discard pattern 1 and the soldering pattern 6 located in close proximity to it. When the state of the browned area at point A was investigated, the results shown in the following table were obtained. Note that tl here is the distance between the soldering patterns.

0 means almost none, Δ means a little bit, X is charred black.

In the above embodiment, the discarding pattern is formed in an L shape, but it is not limited to a square shape, and may be a discarding pattern divided into a plurality of parts 9 as shown in FIG. 5. Furthermore, as shown in FIGS. 6 and 7, a multi-terminal electronic component J2 has a rectangular component body 10 and terminals 11 on both edges extending υ in the longitudinal direction of the component body 10. In this case, discard patterns 14... are provided at both ends of the soldering pattern rows 13.13 provided corresponding to the terminals 11..., and the spot heat sources 15.15 are continuously scanned linearly. It can also be applied to

As explained above, in this invention, a soldering pattern and a discarding pattern are provided on the board body, and the distance between these soldering patterns is tls, the same pattern is the same turn as T, and the distance between the soldering patterns and the discarding pattern is tls. When soldering at a position close to I, the distance from the pattern should be 1. )0≦t
! It is characterized in that the relationship is set to ≦2(tl-T). Therefore, even if the spot heat source is continuously scanned, heat is absorbed by the soldering pattern and the discarding pattern, so that the board body can be reliably prevented from burning, and the quality can be improved.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention, where Figure 1 is a plan view, Figure 2 is a side view, Figure 3 is an enlarged plan view of main parts, and Figure 4 is a plan view of the main parts. 5 is a plan view of the main part showing another embodiment of the present invention, FIG. 6 is a plan view showing a further different embodiment of the present invention, and FIG. 7 is the same as that of FIG. 6. Also in side view. 1...Multi-terminal electronic component, 2...Component body, 3...
Terminal, 4... Board body, 6... Soldering pattern, 7... Discard pattern, 8... Spot heat source. Client agent foreigner Patent attorney Tuling sex Wu Liao S location diagram

Claims (1)

[Claims] In a printed circuit board in which a component body, the outer periphery of the component body, and a multi-terminal component having a large number of terminals are soldered by continuous scanning of a spot heat source, the soldering pattern is discarded on the board body, and an f-turn is used. In addition, the distance between these soldering patterns is '1', the width of the same pattern is T, and the distance between the above-mentioned discarded pattern and the soldering pattern located close to it is t! When 0≦t
, ≦2(tt T).