JPH01304795A - Method for wiring printed board - Google Patents

Abstract

PURPOSE:To require a shorter wiring of the surface and back of a substrate by a method wherein a throughfoot print is formed so as to extend from the surface to the back of the substrate or to reach an intermediate conductive pattern at a foot print for connecting the surface and the back of the substrate and then leads of a surface mounted part of a conductive pattern is connected to the throughfoot print on the surface of the substrate, on the back of the substrate or at the intermediate conductive pattern. CONSTITUTION:At a footprint A for connecting the surface and the back of a substrate, a throughfoot print 10 is formed by filling the solder 10b inside a via 10a which extends from the surface 1a to the back 1b of the substrate 1. On the end of the surface 1a of this throughfoot print 10, a part lead 4 is soldered in the same way as other foot print 2. And on the end of the back 1b, a part lead 4' or a conductive pattern 5' is soldered. At a portion B having an intermediate conductive pattern 11, a throughfoot print 10 is formed from the surface 1a to the intermediate conductive pattern 11 and from the back 1b to the intermediate conductive pattern 11 and the part leads 4 and 4' and other parts are soldered on the surface 1a and the back 1b. By this method, a shorter wiring is required than before and such a high speed printed board is obtained which has little noise.

Description

[Detailed Description of the Invention] [Summary] A wiring method for a printed circuit board on which surface-mounted components such as a flat pack type package are mounted. A printed board that is designed to shorten the wiring on the front and back sides of the printed circuit board to be mounted. Footprints are provided on the board in the same manner as the pin spacing, and a large number of leads of surface mount components are mounted by flatly attaching them to each footprint. In this step, a through footprint extending to the front and back surfaces of the board or the intermediate conductor pattern is formed in the front and back connection footprint portion, and component leads or conductor patterns are connected to the through footprint on the front and back surfaces of the board or the intermediate conductor pattern.

[Industrial application field]

The present invention relates to a wiring method for a printed board on which surface-mounted components such as a flat back type package are mounted, and more particularly, to shortening of wiring connecting the front and back surfaces of the board.

In recent years, in order to increase the packaging density of printed circuit boards, components such as flat pack type packages with narrow pin spacing and terminal leads extending in two or four directions have been increasingly used. With this surface mount component, the mounting area is less than half that of a DTP with the same number of pins, and the mounting density can be doubled by double-sided mounting, making it suitable for components with a large number of terminals.
It has advantages such as being able to be made thinner. However, since the pin spacing between the pins is narrow at the connection part with the component lead, a through hole such as a DIP is formed, and wiring such as using this through hole for connection between the front and back surfaces of the board is not possible.

[Conventional technology]

Therefore, the conventional wiring method for surface-mounted printed circuit boards is as shown in FIGS. 2(a) and 2(b). That is, footprints (lands) 2 are provided on the surface of the substrate 1 at narrow intervals that are the same as the pin intervals, and each lead 4 of the surface mount component 3 is directly flattened and mounted on the footprints 2. A large number of conductor patterns 5 are routed on the substrate 1 to connect to each footprint 2. Here, since the footprint 2 is used only for flattening the component lead 4, when connecting the front surface 1a and the back surface 1b of the board 1, through holes 6 are provided separately for each of the conductor patterns 5. A branching pattern 7 is wired through the through hole 6 on the back side.

(Problems to be Solved by the Invention) By the way, in the conventional example described above, since the wiring on the front and back surfaces 1a and 1b of the substrate 1 is performed using the dedicated pattern 7 and the through hole 6, the wiring area for this is small. When the number of front and back wiring is large in double-sided mounting as shown in the figure, it occupies a large area of the board, leading to a complicated wiring pattern.In addition, the circuit of the front and back wiring becomes long, which reduces noise. This will be disadvantageous when it comes to speeding up, etc.

The present invention has been made in view of these problems, and an object of the present invention is to provide a printed board wiring method that can shorten the front and back wiring in a surface-mounted printed circuit board.

[Means to solve the problem]

In order to achieve the above object, the wiring method of the present invention utilizes the footprint of the board on which component leads are flattened for front and back wiring. Therefore, a through footprint that extends to the front and back surfaces of the board or the intermediate conductor pattern is formed in the front and back connection footprint portion, and leads of surface mount components or conductor patterns are formed in the through footprint on the front and back surfaces of the board or the intermediate conductor pattern. It connects.

[Effect]

Due to the above wiring method, it is normal for both the front and back sides of the board.

Component leads are flattened to the footprint and through footprint for surface mounting. Further, wiring is directly performed on the front and back surfaces of the board via only the through footprint or through the intermediate conductor pattern.

〔Example] Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a board, 2 is a large number of footprints provided on the board 1, 3 is a surface mount component, 4 is a lead,
5 is a conductor pattern, and this component lead 4 is directly soldered to the footprint 2 and mounted, and in the case shown, it is mounted on both sides of the front surface 1a and back surface 1b of the board 1. Here, each part and the corresponding part on the front surface 1a of the back surface 1b are given the same reference numerals with a dash.

Therefore, in the fundprint part A for front and back connections, a via 10a penetrating the front and back surfaces 1a and 1b of the substrate 1 is opened within a narrow range by drilling with a laser beam or the like.
Fill solder 10b inside 0a to create through footprint 10
is formed. And this through footprint 10
A component lead 4 is soldered to the end of the front surface 1a in the same manner as the other footprints 2, and a component lead 4' or a conductor pattern 5' is soldered to the end of the back surface 1b as shown.

On the other hand, in the portion B having the intermediate conductor pattern 11, the intermediate conductor pattern 1
1, a through footprint 10 similar to that described above is formed. Component leads 4, 4', etc. are soldered to this through footprint 10 on the front and back surfaces 1a and 1b.

With this configuration, on the front surface 1a of the board 1, the leads 4 of the surface mount component 3 are surface-mounted on both the footprint 2 and the through footprint 10 in the same plane, and the same is true on the back surface 1b.

Furthermore, electrical connection is made by wiring over a short distance from the component lead 4 on the front surface 1a to the component lead 4' on the back surface 1b via the through-end blind 10 or an intermediate conductor pattern 11 therebetween.

It goes without saying that the present invention can also be applied to single-sided mounting.

〔Effect of the invention〕

As described above, according to the present invention, in a surface-mounted printed circuit board, the front and back connection wiring is performed in the through-footprint of the footprint section, so the wiring of patterns for this purpose is significantly reduced. Packaging density can be improved.

The through footprint of the footprint section shortens the wiring length, which is advantageous for noise countermeasures and increased speed.

If there is an intermediate layer, its conductor pattern can be used in a through footprint, increasing the degree of freedom in wiring.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the printed board wiring method of the present invention, FIG. 2(a) is a sectional view of a conventional example, and FIG. 2(b) is a plan view thereof. In the figure, 1 is the board, 1a is the front surface, 1b is the back surface, 2 is the footprint, 3 is the surface mount component, 4.4' is the lead, 5' is the conductor pattern, 10 is the through footprint, and 11 is the intermediate conductor pattern. shows.

Claims (1)

[Claims] A footprint (2) on the board (1) as well as a pin spacing.
In a printed board on which a large number of leads (4) of surface mount components (3) are mounted flatly on each footprint (2), the front and back surfaces (1) of the board (1) are mounted on the front and back connection footprints.
a, 1b) or the intermediate conductor pattern (11); ) A printed board wiring method that connects component leads (4, 4') or conductor patterns (5') to