JPH0217954B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing double-sided printed wiring boards used in various electronic devices.

Conventional technology In recent years, as seen in the progress of semiconductors, various electronic devices have been desired to have more integrated circuits, smaller products, higher densities, and lower prices, and printed wiring boards have also been developed to meet these needs. There have been remarkable advances in technology.

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, reference numeral 11 indicates a general tin-plated or solder-plated lead wire, and in order to perform high-density mounting, the wire diameter is preferably 0.3 mm to 1.0 mm. This lead wire 11 does not require preparatory work to attach preliminary solder, and is normally inserted into the printed wiring board by an automatic insertion machine from a coiled state on a reel, etc., in the same way as general wire management. It is cut as appropriate at the same time as the work begins.

FIGS. 5a and 5b show a state in which this lead wire 11 is inserted into the double-sided printed wiring board 1 and temporarily fixed.

Here, the upper surface pattern land 9a and the lower surface pattern land 9b represent pattern lands for soldering the lead wires 11, and the land diameter is approximately 2.0 mm. Note that 3a 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 the through holes 3a, 3b are inserted.
Insert into. 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 surface of the double-sided printed circuit board.

In this state, the printed wiring board 1 is immersed in a normal dip solder bath or flow solder bath, and the bent portions at both ends of the lead wires 11 are connected to the bottom pattern lands 9.
Solder to b. This state is shown in FIG. 6b.
Here, 10 is connected to the lead wire 11 and the lower pattern land 9b by dip soldering or flow soldering.
It is solder that electrically connects. After that, as shown in FIGS. 6a and 6b, from the top copper foil pattern side, the lead wire 11 and the top pattern land 9a are soldered using an automatic soldering machine or the like at a location located approximately in the center of the top pattern land 9a. 12 is heat fused and soldered.

In this way, in this method, the solder 12 is directly melted on the top surface copper foil pattern side by a special soldering operation, so the reliability of the electrical connection between the lead wire 11 and the top surface pattern land 9a is extremely high.
Upper surface pattern land 9a and lower surface pattern land 9
Complete electrical continuity can be achieved with b.

Problems to be Solved by the Invention However, with the above configuration, if there is a temperature change in the printed wiring board itself that is greater than a change in the environmental temperature, a creep phenomenon will occur in the soldered parts and the electrical reliability will deteriorate. It may deteriorate. This phenomenon occurs when four different materials (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. . In addition, due to the current demand for higher density, the bending of the lead wire is bent outward from the center line between the two insertion holes, and the bending line is long, resulting in higher density. Improvements were required.

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 manufacturing a double-sided printed wiring board that can further improve the electrical reliability of the connection even under the influence of thermal changes by performing the process on the center line between two points.

Means for Solving the Problems In order to improve the reliability of electrical connection, the present invention makes the wire diameter of the lead wire connecting between the double-sided foils 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, so that the bent portions are located within the copper foil pattern, making soldering reliable. It is structured to enhance sex.

Function: This enables highly reliable electrical connection to be achieved with any double-sided printed circuit board whose printed circuit board material has different thermal expansion and contraction, from phenol to glass epoxy.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 3. First, FIG. 1 shows the order in which lead wires 2 are inserted into a double-sided printed wiring board 1 at an insertion pitch of 2 mm. In FIG. 1a, a typical tin-plated or solder-plated lead wire 2 is bent into a U-shape with a pitch of 2 mm and pushed into through holes 1a and 1b of a double-sided printed wiring board 1 by a moving piece 3. Figure 1b
The lead wire 2 inserted into the double-sided printed wiring board 1 is moved over the upper end surface of the fixed piece 4 arranged so that the movable piece 5 on the lower surface of the double-sided printed wiring board 1 is located between both ends of the lead wire 2. The lead wire 2 is clamped by sliding and then cut and bent along the board surface. In Fig. 1c, the lead wire 2 is pressed against the outer circumferential walls of the two through holes 1a and 1b to create a curve.
is raised to the substrate surface, and the lead wire 2 is made into a curved shape and temporarily fixed to the substrate. The lead wire diameter should be around 0.26mm. Note that 9a and 9b are upper surface pattern lands and lower surface pattern lands.

FIGS. 2a and 2b show the state in which the lead wires are inserted and temporarily fixed into the double-sided printed wiring board as described above. Here, the upper surface pattern land 9a and the lower surface pattern land 9b, which are copper foil patterns, represent pattern lands for soldering the lead wires 2, and in this embodiment, the land diameter is 2 mm.

The lead wires 2 are easily mounted mechanically on the double-sided printed wiring board 1 as described above using an automatic insertion machine. The lead wire 2, which can be inserted into the lead wire 2 and bent as shown in FIG. 3a, is bent onto the center line of the two through holes. This allows the bent lead wire 2 to fit within the land diameter of 2 mm 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 pattern 9 of the printed circuit board on both sides.
The state in which the lead wires 2 are soldered to a and 9b is shown. As for the soldering process, first solder 12
Solder by spot soldering method or simultaneous soldering method. Next, soldering 10 is performed in the manner described above.

Effects of the Invention According to the present invention, even if a printed circuit board material whose shape changes due to thermal expansion and contraction is used,
Insert U-shaped lead wires into the two lead wire insertion holes provided in the printed circuit board material, and place both ends of the lead wires along the copper foil surface, facing inward, and facing each other on the hole wall. By bending the lead wire into a curve so that it touches the outer circumferential surface and soldering it to the copper foil pattern, thermal changes in each component material that makes up the double-sided printed circuit board can be bent to the curved part (redundant part) of the lead wire. As a change, it is possible to produce a double-sided printed wiring board that can be absorbed and absorbed. In addition, in the double-sided printed wiring board manufactured according to the present invention, since the lead wires for obtaining electrical connection on both sides face each other on the center line of the two through holes, the copper wire between the two through holes is The folded portion is located within the foil pattern, improving soldering reliability.

[Brief explanation of drawings]

Figures 1a, b, and c are schematic sectional views of a board showing a method of connecting a double-sided printed wiring board in an embodiment of the present invention, Figure 2a is a plan view of the same board, and Figure 2b is a schematic cross-sectional view of the same board. Figure 3a is a plan view of the board after soldering, Figure 3b is a schematic sectional view, Figure 4 is a plan view of the lead wires, and Figure 5a is the board showing the conventional connection method. FIG. 5B is a plan view, FIG. 5B is a schematic sectional view, FIG. 6A is a plan view of the board after soldering, and FIG. 6B is a schematic sectional view. 1... Double-sided printed wiring board, 1a, 1b... Through hole, 2... Lead wire, 3, 5... Moving piece, 4...
Fixed piece, 9a...Top pattern land, 9b...
Bottom pattern land, 10, 12...Solder.

Claims (1)

[Claims] 1. An insulating substrate having a copper foil pattern on the top surface and a copper foil pattern on the bottom surface, two through holes are provided between the copper foil patterns on both sides, and a U-shaped lead wire is formed. Both ends of the lead wire are inserted into the through hole, and both ends of the lead wire are held and cut by a fixed piece and a pair of movable pieces located between both ends of the lead wire, and both ends of the lead wire are wrapped with copper foil. Bend the lead wires in a curved manner so that they face each other inwardly along the surface and in contact with the outer circumferential surface of the hole wall, and connect both ends of the lead wires to the copper foil pattern on the lower surface by soldering, and A method for manufacturing a double-sided printed wiring board, characterized in that the lead wire and the upper copper foil pattern are soldered from the upper copper foil pattern side.