Method of circuit connection across both surfaces of substrate

Details Method of circuit connection across both surfaces of substrate Method of circuit connection across both surfaces of substrate

1984-07-26

1986-06-03

Goldberg, Howard N.

Metal working

Method of mechanical manufacture

Electrical device making

2281801, H05K 1304

Patent

active

045921377

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a method of making a circuit connection across both surfaces of substrate in the field of electronic circuit assembling technique.


BACKGROUND ART

Heretofore, for circuit connection across both surfaces of substrate, a through-hole substrate is generally known. Part of this through-hole substrate is shown in FIG. 1. Referring to FIG. 1, 1 denotes a substrate formed of an insulating resin; 2a and 2b denote copper foils which are electrically conductive members formed on both surfaces of substrate in respective specified patterns; 3 denotes a through-hole for fitting parts piercing the substrate 1 and copper foils 2a and 2b; 4 denotes a copper plating layer formed on the internal circumferential wall of the through-hole 3 and on copper foils 2a and 2b by chemical plating or electrical plating, which conductively communicates between the copper foils 2a and 2b. Numeral 5 designates a solder layer formed by dipping or flow-soldering. Such a through-hole substrate is expensive because of the cost for forming the copper plating layer 4 and is, therefore, hardly adaptable for commercial electronic equipment. Moreover, because of the fear of inadequate conduction resulting from lack of copper plating layer 4 at the end of the through-hole 3 or cutting-off of the copper plating layer 4 caused by inserting lead wires of parts, it has heretofore been necessary to ensure reliability of conduction by floating the solder 5 up over the copper foil 2a as shown in the drawing when conducting the dipping or flow-soldering and, accordingly, to strictly control the temperature of the solder tank and the soldering time. As a means for overcoming such a difficulty, a substrate to be printed on both surfaces thereof by through-pin system is available. FIG. 2 shows part of it. Referring to FIG. 2, 6 designates a conductive pin pressed into the through-hole 3, which is en bloc soldered on the bottom copper foil 2b by way of dipping or flow-soldering after mounting other electronic parts on the printed substrate and which is further soldered on the top copper foil 2a, thereby effecting conduction across the copper foils 2a and 2b. On such a printed substrate, connecting of the pin 6 with the copper foil 2a has heretofore had to be done by hand at low efficiency, because other electric parts existed on the same surface. Or when soldering the pin on the copper foil 2a, the solder 5 on the side of the copper foil 2b already soldered partly melts, resulting in inadequate conduction.


DISCLOSURE OF THE INVENTION

According to this invention, into through-holes each equipped on its perimeter with conductive members such as copper foils, etc., applied as printed wiring on both surfaces of insulating substrate, etc., an electrically conducting wire provided with a solder ball is inserted and by soldering the conductive member on one surface with the conducting wire by way of dipping or flow-soldering, etc., the conducting wire and the conductive member on the surface not being soldered are joined by melting the aforementioned solder ball, thereby making the circuit connection across both surfaces of substrate.


BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are sectional views of substrates each showing the conventional circuit connection across both surfaces of substrate;
FIG. 3 is a perspective view of a conducting wire having a solder ball thereon which is an embodiment of this invention;
FIGS. 4a and 4b are sectional views of a substrate showing the connection forming process in the method of joining both surfaces of substrate, using the conducting wire of FIG. 3;
FIG. 5 is a perspective view of a conducting wire having a solder ball thereon which is another embodiment of this invention;
FIGS. 6a and 6b are sectional views of the substrate showing the forming process in the method of making the connection across both surfaces of substrate, using the conducting wire of FIG. 5.


THE MOST PREFERABLE MODE IN EXERCISING THE INVENTION

In the following, an embodiment of this invention

REFERENCES:
patent: 2915678 (1959-12-01), Frazier et al.
patent: 3002481 (1961-10-01), Hutters
patent: 3780433 (1973-12-01), Lynch
patent: 3932934 (1976-01-01), Lynch et al.
patent: 4373259 (1983-02-01), Motsch

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