JPS61263193A - Connection of double-side printed wiring 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 Field of the Invention The present invention relates to an improvement in a method for electrically connecting double-sided copper foil patterns of double-sided printed wiring boards used in various electronic devices.

Conventional technology In recent years, various electronic devices have been developed with the advancement of semiconductors.
There are demands for more integrated circuits, smaller products, higher densities, and lower prices, and the technology of printed wiring boards has made remarkable progress in meeting these needs.

In the conventional technology, even if double-sided printed foils are connected via lead wires in a double-sided printed circuit, a creep phenomenon occurs in the soldered parts due to changes in environmental temperature, etc., and electrical reliability deteriorates. Further, since the lead wire bending portion is bent outward from the center line between the two insertion holes, there are problems such as low density and lack of soldering reliability.

A conventional example will be described below with reference to the drawings.

In FIG. 4, 11 is a general tin-plated wire or solder-plated lead wire, and in order to perform high-density mounting, the wire diameter (diameter) should be 0.3 ff to 1.5 ff. Off is desirable. This lead wire 11 does not require preparatory work to attach preliminary solder, and is normally inserted into a printed wiring board by an automatic insertion machine from a coiled state on a reel, etc., as in general wire management. It is cut off as appropriate at the same time as it occurs.

Figure 6 (2L), (b) shows this lead #! 11 is inserted into the double-sided printed wiring board 1 and temporarily fixed.

Here, the upper surface pattern land 91L and the lower surface pattern land 9b represent pattern lands for which the lead wire 11 is half-attached, and the land diameter is approximately 2.5 mm. It is set to On. In addition, 3
A and 3b are a pair of through holes into which both ends of the lead wire 11 are inserted.

For the printed wiring board 1 as described above, the lead wires 11 are cut to a predetermined size and inserted into the through holes 3&, 3b. The lead wire 11 can be easily mechanically mounted using an automatic insertion machine, and the lead wire 11 is temporarily fixed by bending both ends of the lead wire 11 protruding from the back side of the double-sided printed circuit board. .

In this state, the printed wiring board 1 is immersed in an ordinary dip soldering bath or a flow soldering bath, and the bent portions at both ends of the lead wires 11 are soldered to the lower surface (turn lands 9b).

This state is shown in FIG.

Here, 10 is solder that electrically connects the lead wire 11 and the lower surface pattern land 9b by dip soldering or flow soldering. After this, Figure 6 (&), (b)
As shown in the figure, from the top copper foil pattern side, the lead wire 11 and the top pattern land e& are automatically soldered at a location located approximately in the center of the top pattern land 9a by heat-sealing the solder 12 using a machine or the like. Solder.

In this way, in this method, the reliability of the electrical connection between the upper surface copper foil (the solder 12 is directly melted on the lead wire 11 and the upper surface) and the turn land 9a is improved. becomes extremely high, and the upper surface pattern land 9
Complete electrical continuity can be achieved between & and the lower surface turn land 9b. ◎Problems to be Solved by the Invention However, with the above configuration, the printed wiring board itself is exposed to large temperatures due to changes in environmental temperature. If there is a change, a creep phenomenon may occur in the soldered part, which may deteriorate electrical reliability. This phenomenon occurs when four different materials, the printed circuit board material, copper foil, solder material, and lead wire material, expand and contract under the influence of heat, and the stress is concentrated in the solder material, causing a creep phenomenon. occurs. In addition, due to the current demand for higher density, the bending of the lead wire is required in the insertion hole 2.
Improvements to higher density were required due to the fact that it was bent outwards on the center line between points and the bend line was long.

In order to solve the above conventional problems, the present invention improves the insertion shape of the lead wire in order to shift the stress concentration point from the solder material to the lead wire, and also bends the lead wire into the insertion hole to cope with higher density. The object of the present invention is to provide a method for connecting double-sided printed wiring boards, which can further improve the electrical reliability of the connection even under the influence of thermal changes by performing the connection on the center line between two points.

Means to Solve the Problem In order to improve the reliability of electrical connection, the present invention makes the wire diameter of the lead wire connecting the double-sided seedlings smaller, and the insertion shape is changed to two insertion holes. It has a round shape that contacts the outer peripheral wall of the lead wire, and the contraction and expansion of the material due to heat is absorbed by the slack of the lead wire. On the other hand, in order to accommodate higher density, the lead wires are bent along the board surface and bent over the center line of the two insertion holes so that they face each other, and the bent portions are positioned within the copper foil pattern and soldered. The structure is designed to increase reliability.

As a result, the reliability of electrical connection is high for any double-sided printed circuit board whose printed circuit board material has different thermal expansion and contraction, from phenolic material to glass epoxy material, and by improving the lead wire bending shape. High density can be ensured.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 3. First, in FIG. 1, a double-sided printed wiring board 1
The insertion order of the lead wires 2 with an insertion pitch of 2jrll is shown. Figure 1 (L) shows a general tin-plated or solder-plated lead wire 2 bent into a U-shape with a pitch of 2H and inserted into the through holes 1m and 1b of the double-sided printed wiring board 1 by the moving piece 3. Push it in. FIG. 1(b) shows the lead wire 2 inserted into the double-sided printed wiring board 1 after the movable piece 6 on the lower surface of the double-sided printed wiring board 1 slides on the fixed piece 4 to grip the lead wire 2. Cut and fold along the board surface. In FIG. 1(C), the lead wire 2 is pressed against the outer circumferential walls of the two through holes 1a and 1b, and the lead wire 2 is moved by the movable piece 1 in order to create a curve. The lead wire diameter is preferably about 0.26ff.

Note that 91L and 9b are upper surface pattern lands and lower surface pattern lands.

Figure 2 (&) and (b) show the state in which the lead wires have been inserted and temporarily fixed into the double-sided printed circuit board as described above.
It is something. Here, the top pattern land 9 is a copper foil pattern! The L1 lower surface pattern land 9b is a pattern land for soldering the lead wire 2, and in this embodiment, the land diameter is 2 mm.

The lead wires 2 can be easily mounted mechanically on the double-sided printed wiring board 1 as described above using an automatic insertion machine.
The lead wires 2 are curved in the outer peripheral walls of the two insertion holes 11L and 1b so that they can be inserted in close contact with each other, and the lead wires 2 bent as shown in Fig. 3(a) are inserted into the centers of the two through holes. It can be bent on a line. This means that the bent lead wire 2 fits within the land diameter of 21III to which it is soldered, which improves the reliability of soldering and eliminates any influence when attaching other parts in the subsequent process.

Figure 3 shows the pattern 9& of the printed circuit board on both sides.

A state in which the lead wire 2 is soldered to 9b is shown. In the soldering process, the solder 12 is first soldered by a spot soldering method or a simultaneous soldering method. Next, solder 1o
is carried out using the method described above.

Effects of the Invention As described above, the present invention has the following advantages:
The lead wires are curved and slack in the two through-holes, and the expansion and contraction of the four elements (printed circuit board material, copper foil lead material, and solder material) due to heat is absorbed by the slack of the lead wires.
Since the lead wire has a shape that changes, creep phenomena such as solder parts, etc. do not occur. In addition, to ensure high density and high reliability, the bent lead wires are placed facing each other on the center line of the two through holes, and are tightly attached to the board surface and securely housed within the copper foil land. , it improves solderability, eliminates the influence of parts mounting in post-processing, ensures high density, and high reliability, and has great practical effects.

FIG. 2(a) is a schematic cross-sectional view of the board showing the method of connecting wire plates, FIG. 2(b) is a schematic cross-sectional view of the same board, and FIG.
a) is a plan view of the board after soldering, FIG. 3(b) is a schematic cross-sectional view, FIG. 4 is a plan view of the lead wire, and FIG. 6 (2L)
is a plan view of the board showing the conventional connection method, FIG. FIG.

1...Double-sided printed wiring board, 1a, 1b...
...Through hole, 2...Lead wire, 3,6...
...Moving piece, 4...Fixed piece, 9a...
Upper surface pattern land, 9b... Lower surface pattern land, 10, 12... Solder.

Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure w43 Figure 4rl! JI I

Claims (1)

[Claims] An insulating substrate having a copper foil pattern on the top surface and a copper foil pattern on the bottom surface is provided, two through holes are provided in the insulating substrate so as to sandwich the copper foil patterns on both sides, and both ends of the lead wire are formed into a U-shape. into the through-hole, and bend it inward along the copper foil surface so that both ends are facing each other, and the lead wires in the two through-holes are each in contact with the outer peripheral surface of the hole wall, and are curved. Both ends of the lead wire are soldered and connected to the lower copper foil pattern, and from the other upper copper foil pattern side, the lead wire and the upper copper foil pattern are soldered. A method for connecting a double-sided printed wiring board, comprising electrically connecting a copper foil pattern through the lead wire.