JPS6214959B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is used as a board for electronic circuits in various electronic devices, and particularly relates to a double-sided printed board having conductive patterns such as copper foil patterns formed on both sides.

Conventionally, various structures as shown below have been employed for electrical connection between conductive patterns (front pattern and back pattern) on both sides of a double-sided printed circuit board.

As an example, a structure using plating as shown in FIG. 1 is known. In the device shown in FIG. 1, a through hole 4 is provided on both sides of a substrate 1 to pass between conductive patterns 2 and 3 formed by copper foil patterns, etc., and the through hole 4 is formed by chemical plating and electroplating. Cylindrical copper plating layer 5 on the inner wall surface of
is formed, and conductive patterns 2,
This is a connection between the three. However, with this structure, it is difficult to manage the plating process. In particular, cracks are likely to occur in the copper plating layer 5 at the corner portions 4a of the through holes 4, and connection failures are likely to occur. Furthermore, it is necessary to finish the inner wall surface of the through hole 4 into a uniform and clean surface so that the copper plating layer 5 can easily adhere to it, making it impossible to perform punching processing that can be processed quickly in large quantities, and drilling processing with poor processing efficiency. This results in higher costs. Furthermore, the work process of the plating process itself is complicated, resulting in poor work efficiency and high costs.

Another known example is one using eyelets, as shown in FIG. In this structure, an eyelet 7 made of copper or the like is inserted into the through hole 4, and both ends 7a and 7b of the eyelet 7 are crimped to the conductive patterns 2 and 3 on both sides to connect the patterns 2 and 3. It is. Furthermore, as shown in FIG. 3, a device using through-hole pins is also known.
In the device shown in FIG. 3, a through-hole pin 11 made of copper or the like and having a head 10 larger than the diameter of the through-hole 4 at one end is inserted into the through-hole 4 from the upper surface side (component mounting surface side). Then, the head 10 is connected to the conductive pattern 2 on the upper surface, and in this state, a solder dip (dip solder) is applied from the lower surface side to each of the conductive patterns 2 and 3 on both sides.
The through-hole pins 11 are used to connect the two through-hole pins 11. However, in the case of such a structure, since solder dipping is performed with the upper end opening of the through hole 4 closed with the head 10 of the through hole pin 11, the flux attached to the solder surface during the solder dipping is performed. There is no place for the gas generated from such things to escape. As a result, blowholes occur on the solder surface, resulting in disadvantages such as a lack of reliability in soldering.
In addition, since the thermal contraction of the solder applied by the solder dip and the substrate heated during the solder dip does not match, the solder and the conductive pattern are Problems such as cracks occurring between the two may also occur, resulting in poor connection.

Therefore, the present invention has been proposed with the aim of correcting all the drawbacks and problems of the conventional devices as described above. In particular, we would like to provide highly reliable soldering, which is performed when connecting conductive patterns formed on both sides of a board by connecting pins, without the occurrence of connection failures, and with an easy work process. That is.

The present invention will be described below with reference to embodiments shown in the drawings.

First, in order to configure the present invention, for example, the fourth
A double-sided printed circuit board 20 as shown in the figure is prepared. This double-sided printed circuit board 20 is formed by providing conductive patterns 22 and 23, such as copper foil patterns, on both sides of a board 21, sandwiching the board 21 therebetween. Through holes 26 and 27 passing through the substrate 21 are formed in land portions 24 and 25, which are parts of the conductive patterns 22 and 23 formed on both sides of the substrate 21 and are not provided with solder resist, respectively. ing. Through holes 26, 2 drilled here
7 is bored so that no conductive pattern is formed around the open ends 26a and 27a located on one side or the other side of the substrate 21. That is, the conductive patterns 22, 23 are arranged so that at least conductive patterns, especially land portions, are not formed at positions corresponding to the open ends 26a, 27a of the through holes 26, 27 formed in the substrate 21.
form.

On the double-sided printed circuit board 20 formed in this way,
For example, connection pins 28 formed as shown in FIGS. 5 and 6 are provided. That is, the connection pin 28 disposed here is formed by bending a conductive filament such as a copper wire. Figures 5 and 6
The connecting pin 28 as shown in the figure is formed by bending one end side of a linear body with a connecting portion 29 at its center at an angle of approximately 90 degrees with respect to the connecting portion 29, and forming a first leg portion 3.
0, and the other end of the connecting portion 29 is wound approximately 360 degrees in the horizontal direction with respect to the connecting portion 29 to form an arcuate solder patch 31 having a predetermined area. The other end side that is continuous with the attaching part 31 is connected to the connecting part 29 in the same way as in the formation of the first leg part 30.
The second leg portion 3 is bent at an angle of about 90 degrees to the second leg portion 3.
2. Solder 33 for connecting the connecting pin 28 and the conductive pattern 22 is provided in the solder mounting portion 31 which is a part of the connecting pin 28 bent into a substantially U-shape in this manner. The distance between the first and second leg portions 30 and 32 formed on both sides of the connection pin 28 corresponds to the pair of through holes 26 and 27 formed in the substrate 21.
This corresponds to the interval between.

The connection pin 28 formed in this way is connected to the first
The second legs 30 and 32 are respectively inserted into the through holes 26 and 27 formed in the substrate 20 to form the seventh leg.
Arrange as shown in the diagram. In other words, the first leg portion 3 is located at a biased position with respect to the solder application portion 31.
0 is inserted into a through hole 26 formed from a portion of a conductive pattern 23 formed on the lower surface side of the substrate 21,
One of the second leg portions 32 is inserted into a through hole 27 formed from a portion of the conductive pattern 22 formed on the upper surface side of the substrate 21, and the solder mounting portion 31 to which the second leg portion 32 continues is It is placed on the conductive pattern 22 formed on the upper surface side. In the state shown in FIG. 7, a solder dip is applied from the lower surface side of the substrate 20, which is opposite to the upper surface, which is the surface on which the connecting pins 28 are inserted. Then, the conductive pattern 23 formed on the lower surface side of the double-sided printed circuit board 20 and the first leg portion 30 are connected by the molten solder 34 supplied at the time of soldering dip, and the
The conductive pattern 22 and the second leg 32 formed on the upper surface side are heated by heat transmitted from the end of the second leg 32 protruding from the lower end of the through hole 27 during soldering. The connection is made by solder 33 provided on the solder patch 31 which is melted. That is, the conductive pattern 23 on the lower surface side of the substrate 21 is provided only on the side of the through hole 26 through which the first leg 30 is inserted, and on the lower surface side of the substrate 21 in the through hole 27 through which the second leg 32 is inserted. Since the surface of the substrate 21 is exposed, even if a solder dip is applied, molten solder is not supplied to the second leg portion 32 and its surroundings. As described above, the conductive patterns 22 and 23 on both sides of the substrate 21 are electrically connected by the connecting pins 28 as shown in FIG.

When connecting via the connection pins 28 as described above, the through holes 26 are formed from a part of each of the conductive patterns 22 and 23 formed on both sides of the substrate 21 toward the substrate 21 side. , 27, which are located on the side where the conductive pattern is not provided, can be soldered while remaining open. Therefore, it is possible to perform so-called good degassing in which gas caused by flux generated in the through holes 26, 27 during solder dipping is reliably released from the open ends 26a, 27a of the through holes 26, 27. Therefore, extremely good soldering can be performed without blowholes or the like occurring on the soldering surface. Further, according to the present invention, the through hole 2
The legs 30 and 32 of the connection pin 28 need only be inserted through the holes 6 and 27, and there is no need to plate or solder the inner peripheral surfaces thereof. Therefore, the through holes 26, 27
Since there is no need to finish the inner circumferential surface to a particularly clean surface, these through holes 26 and 27 can be formed extremely easily, for example, by punching. Furthermore, the present invention provides each through hole 2 formed in the substrate 21.
The soldered portions in 6 and 27 are on opposite sides sandwiching the board 21, that is, in each of the through holes 26 and 2.
Soldering portions 7 are applied on one side of the top surface and on the other side of the bottom surface. Therefore, the heat shrinkage of the board 21, which is heated during soldering, can be absorbed on the side opposite to the soldering part, and cracks that conventionally occur between the conductive patterns 22, 23 and the solders 33, 33 can be reliably prevented. .

By the way, the connection pin 28 used in the present invention
The double-sided printed circuit board 20 formed as shown in FIG. A connecting pin 28 having a connecting portion 29 connecting between 30 and 32 and not having a solder dip (dip solder) on the board 20.
The second leg portion 3 of the connecting pin 28 is inserted into a conductive pattern 22 formed on the upper surface side of the insertion side and a through hole 27 formed corresponding to the conductive pattern 22.
It is only necessary that the solder 33 necessary and sufficient for connecting the two connection pins 28 to 2 is provided in advance on a portion of the connection pin 28. Therefore, various types of connection pins 28 configured as described below can be used.

The connecting pin 28 shown in FIGS. 9 and 10 has a semicircular curved portion formed in the vicinity of the second leg portion 32 of the connecting portion 29, and this curved portion is used as the solder mounting portion 31. Then, attach the second leg 3 to this arm bending part.
2 and the conductive pattern 22 on the upper surface of the substrate 21 by applying solder 33 thereon.

Moreover, what is shown in FIGS. 11 and 12 is a solder filling portion 31 formed at both ends of the connecting portion 29 in an arcuate manner as shown in FIGS. 5 and 6 described above. 31 was formed. Then, solder 33 is applied to one solder application part 31. If formed in this manner, since the shape is symmetrical, the directionality of the solder application portion can be eliminated, and the work of applying the solder 33 can be easily performed.

Further, the connecting pin 28 shown in FIGS. 13 and 14 is formed by punching a conductive metal plate such as a thin copper plate. That is, as shown in FIG. 15, the filament 36 is formed by punching out a metal plate so as to have a circular bulge 35 in the middle. A fold line 3 is formed so as to form a connecting portion 29 and first and second leg portions 30 and 32 on this filament body 36.
7 and 38 are provided and bent along the fold lines 37 and 38 to form a connecting pin 28 as shown in FIGS. 13 and 14. Then, the bulging portion 35 located on the second leg portion 32 side is used as the solder filling portion 31,
Solder 33 is provided here. By the way, connection pin 2
The bulging portion 3 where the solder 33 is filled when forming the solder 8
5 is preferably located on the second leg 32 so as to be located exactly on the conductive pattern 22 on the top surface of the substrate 21. Therefore, the proximal end portion 32a of the second leg portion 32 is cut into the bulge portion 35 so that the proximal end portion 32a of the second leg portion 32 is
5, and the fold line 38 is also aligned with the bulge 3.
5.

The various connection pins 28 described above have solder 33 applied to a solder application part 31 formed in the vicinity of the second leg part 32 of the connection part 29, but the solder application part 31 is It is not limited to these.

For example, as shown in FIGS. 16 and 17,
A conductive linear body (conductor) is bent into a U-shape to form first and second leg parts 30 and 32 at both ends of the connection part 29.
A substantially central portion of the connecting portion 29 of the connecting pin 28 is formed to bulge out in a semicircular shape,
This connection pin 28 and the conductive pattern 2 on the board 21
It is also possible to form a solder application portion 31 having a predetermined area on which solder 33 sufficient to connect 2 can be applied.

When using the connecting pin 28 in which the solder mounting portion 31 is provided at a substantially central portion of the connecting portion 29, which is an intermediate position between the first and second leg portions 30 and 32, it is possible to Even if the conductive patterns 22, 23 are not positioned at positions corresponding to the open ends 26a, 27a of the through holes 26, 26, solder dipping is performed with the open ends 26a, 27a reliably kept open. be able to. For example, as shown in FIG. 18, conductive patterns 22 and 23 formed on both sides of the substrate 21 are
through-holes 26 and 27 for inserting the connecting pin 28 are formed in these opposing parts.
to be drilled. Then, the connecting pin 28 formed as shown in FIGS. 16 and 17 is inserted through the through holes 26 and 27 via the first and second legs 30 and 32, and the connecting pin 28 is inserted through When a solder dip is applied from the bottom side of the board 21 opposite to the side surface,
The conductive pattern 23 formed on the lower surface side of the double-sided printed circuit board 20 and the first and second legs 30, 32 are connected by molten solder 34 supplied during soldering dip, and the conductive pattern 23 formed on the lower surface side of the double-sided printed circuit board 20 is connected to The conductive pattern 22 and the connecting portion 29 formed on the conductive pattern 22 and the connecting portion 29 are connected to each other by heat transmitted from the ends of the first and second leg portions 30 and 32 protruding from the lower ends of the through holes 26 and 27 during soldering. The connection is made by solder 33 provided on the solder patch 31 which is then melted. At this time, since the solder 33 is provided in the solder mounting portion 31 provided approximately at the center of the connecting portion 29, even if it is melted by heat, the open ends 26a of the through holes 26, 27, It does not flow out to 27b and does not block the through holes 26, 27. Therefore, the opening ends 26a, 27b of the through holes 26, 27 can be left open during soldering, and the double-sided printed circuit board 20 can be opened while ensuring so-called degassing as in the previous embodiment. conductive pattern 22 on both sides,
23 can be connected using connecting pins 28.

The various connection pins 28 described above can be constructed simply by placing the solder 33 on the solder platter 31, which has a sufficiently large area relative to the connection portion 29, etc., so manufacturing is extremely easy. It's easy.

As described above, the present invention completely opens one or the other opening end of each through-hole through which a connecting pin is inserted, thereby ensuring gas venting at the through-hole portion during soldering, and a double-sided printed circuit board. Since the conductive patterns on both sides are connected by soldering the connecting pins, there is no blow hole on the solder surface due to the above-mentioned gas venting failure, and the soldering reliability is extremely high. Good soldering can be performed very easily, and the above-mentioned connection can be obtained very well. Further, the through hole can be formed very easily by punching, for example, and the workability is good and the cost is very low.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are sectional views each showing an example in which conductive patterns on both sides of a conventional double-sided printed circuit board are connected. FIG. 4 is a sectional view showing a double-sided printed circuit board constituting the present invention, and FIGS. 5 and 6 are examples of connection pins used in the present invention. FIG. Figure 6 is a perspective view. FIG. 7 is a cross-sectional view showing the connection pins arranged on the double-sided printed circuit board, and FIG. 8 is a cross-sectional view showing the connection pins connected by soldering. 9 and 10 show other examples of the connecting pin, FIG. 9 being a plan view thereof and FIG. 10 being a front view thereof. FIGS. 11 and 12 show still other examples of connection pins.
FIG. 1 is a plan view thereof, and FIG. 12 is a front view. 13 and 14 show still other examples of connection pins, FIG. 13 is a plan view thereof, and FIG.
The figure is a front view, and FIG. 15 is a plan view showing the state in which the connection pin is molded. FIGS. 16 and 17 show still another embodiment of the connecting pin, with FIG. 16 being a plan view thereof and FIG. 17 being a front view thereof. FIG. 18 is a sectional view showing another embodiment of the present invention using the connection pins shown in FIGS. 16 and 17. 20... Double-sided printed circuit board, 21... Board, 2
2, 23... Conductive pattern, 26, 27... Through hole, 28... Connection pin, 30... First leg, 3
1...Solder application part, 32...Second leg part, 33
...Solder on the connection pin.

Claims (1)

[Claims] 1. A double-sided printed circuit board having a conductive pattern formed on both sides of the board with the board sandwiched therein and having a through hole in each part, has a solder mounting part having a predetermined area and bulges formed by bending the conductor. A connecting pin formed with a leg portion that can be inserted into each of the through holes is provided by inserting the leg portion into each of the through holes, and a lower surface side opposite to the insertion side surface of the connecting pin. A double-sided printed circuit board formed by applying a solder dip to connect the conductive patterns on both sides of the board via the connection pins.