JP2015185774A - lead pin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead pin with simple structure that can be formed with good mass productivity, without requiring any special processing on the printed wiring board side, and capable of reducing occurrence of blow hole by enhancing solder wicking when soldering.SOLUTION: A lead pin 1 including a medium brim 20 around a prismatic substrate 10 is configured to form a recess 22 in the thickness direction of the medium brim 20, in the direction of the substrate 10 from the outer periphery of the medium brim 20.

Description

The present invention relates to a lead pin electrically connected to a conductor portion formed on a printed wiring board. In particular, the present invention relates to a lead pin that improves solderability when the lead pin is mounted on a printed wiring board.

When mounting components or the like on a printed wiring board, mounting by soldering is common. In particular, in the mass production stage, it is required to improve the efficiency of soldering and mounting of components, etc., so the components are temporarily mounted on a printed wiring board, and the printed wiring board is dipped in a solder bath to solder the components. The mounting work is a series of work steps, and the efficiency of soldering work for mounting components and the like on the printed wiring board is improved.

However, in these mass production processes, there is a risk that the component and the conductor portion of the printed wiring board are not sufficiently soldered. More specifically, when the component is a lead component, first, the lead portion of the component is inserted into a through-hole formed in advance on the printed wiring board and is temporarily attached, and then dipped into the solder bath. Further, there is a concern that the solderability may be insufficient between the lead portion and the conductor portion of the printed wiring board due to poor solder rotation.

This concern arises because a specific sealed space is created between the printed wiring board and the component main body. That is, the space between the printed wiring board and the component main body (for example, an electrolytic capacitor) is surrounded by the thickness of the outer sleeve of the component main body and the lead-out end surface of the lead portion of the component main body. by.

The space portion is connected to the outside (solder surface side) through a clearance between a through hole formed in the substrate through which the lead portion is inserted and the lead portion in a temporarily mounted state before soldering. When the printed circuit board is dipped in the solder bath, the gap between the through holes is closed by the solder, and the space portion becomes a sealed space. At this time, due to the heating during soldering, the air in the sealed space thermally expands and blows out from the through hole to the solder surface side, and blows off the solder before solidification. As a result, the solder does not sufficiently turn around the lead portion, and the lead portion and the conductor portion of the substrate may not be sufficiently soldered.

In order to solve such a concern, the following solutions have been disclosed conventionally. Broadly speaking, there are two types: one having a specific solution structure on the printed wiring board side and one having a specific solution structure on the electronic component side.

First, as a thing provided with a specific solution structure in a printed wiring board, there exists a thing shown in patent document 1 and patent document 2. FIG.

In Patent Document 1, a rectangular step portion is previously formed by screen printing around a through hole formed in a substrate so that the above-described sealed space does not occur. When the electronic component main body is temporarily mounted on the printed wiring board by the stepped portion, the electronic component main body is slightly lifted from the printed wiring board, and a gap is formed between the printed wiring board and the electronic component main body. The Therefore, even if the air in the space portion is thermally expanded during soldering, the thermally expanded air can escape to the outside through the gap, so that the solder also turns well to the soldered portion of the lead portion, and the conductivity is increased. Is sufficiently secured.

In Patent Document 2, a vent hole communicating with the space portion and the outside is formed in the vicinity of the through hole in the substrate so that the above-described sealed space does not occur. Therefore, even if the air in the space portion is thermally expanded, the thermally expanded air can escape to the outside through the vent hole, so that the solder can be well turned to the soldered portion of the lead portion, and sufficient conductivity is ensured. It is what is done.

Next, as a device having a specific solution structure on the electronic component side, for example, a protrusion is provided on the printed wiring board surface side of the electronic component main body so that the above-described sealed space does not occur. Some electronic component bodies are slightly lifted from the printed circuit board so that the electronic component body is not in close contact with the printed circuit board.

Further, Patent Document 3 discloses an example of a press-fit pin formed so as not to generate the above-described sealed space as a component to be mounted on a printed wiring board. Normally, a press-fit pin is a type in which a pin formed slightly larger than the diameter of the through hole is driven, and after installation, the through hole is closed with a pin head to maintain airtightness. A convex flat plate is formed below the pin head, and a convex flat portion having the same thickness as the head thickness is provided on the inner side of the pin head having a diameter of about twice the pin diameter, and air is passed between the two openings of the through hole. Is intended to be obtained. For this reason, the above-described sealed space does not occur, and solderability can be improved during soldering.

JP-A-6-169142 (FIG. 1) Japanese Utility Model Publication No. 63-102273 (FIG. 1) JP-A-1-120780 (FIG. 1)

In the case of providing a specific solution structure on the printed wiring board side described above, for example, when changing the shape of a component at the time of design change, such as when changing an electronic component to be mounted on the printed wiring board, The case where the said step part and the said air vent which were formed in the board | substrate do not respond | correspond to the component shape after a change is assumed. That is, when the design is changed, it is necessary to change not only the electronic component but also the pattern of the printed wiring board, and there is a possibility that costs and labor for changing the board may occur.

In a press-fit pin disclosed as having a specific solution structure on the electronic component side, it is necessary to process and form a convex flat plate having the same thickness as the head thickness inside the pin head, which makes the pin processing complicated. There is a risk that the mass productivity of the pin may be reduced. In addition, since the pin head has a structure that covers the through hole, once the solder turns inside the pin head, the pin head becomes a heat sink and the solder tends to harden, blocking the ventilation path, and provided below the through hole and the pin head. There is a possibility that the gas in the space with the convex flat part is contracted as it is and blow holes are generated. In other words, although the press-fit pin is raised from the substrate by the thickness of the convex flat part, the top of the through hole is shaped to be covered with a pin head, so there is a possibility that a blow hole will occur. The

Therefore, the present invention has been made in view of the above problems, and does not require any special processing on the printed wiring board side, and the lead pins themselves can be formed with a simple structure with high mass productivity, and can be easily soldered when soldering. An object of the present invention is to provide a lead pin capable of improving the resistance and reducing the occurrence of blow holes.

A lead pin according to the present invention is configured to solve the above-described problem, and is a lead pin provided with a center collar around a prismatic base, and the center of the center is formed from the outer periphery of the center collar toward the base. A concave portion is formed in the thickness direction.

According to such a configuration, by providing a recess in the thickness direction of the middle wall, when the lead pin is inserted into the printed wiring board, the space formed on the surface of the printed wiring board is in communication with the through hole, and always Since the air flow path can be maintained between the front and back sides of the printed wiring board, there is no sealed space due to the center of the lead pin covering the through hole of the printed wiring board, and the solder turns to the lead pin. It is possible to reduce the occurrence of blow holes without blocking the ventilation path. Further, in the lead pin manufacturing process, the concave portion can be press-formed together with the formation of the intermediate collar, so that the mass productivity of the lead pin is improved.

Moreover, the said recessed part can employ | adopt the structure provided point-symmetrically with respect to each surface around the said base | substrate.

According to such a configuration, since the concave portion in the center rib is formed point-symmetrically with respect to the longitudinal axis center of the lead pin, a plurality of the ventilation paths can be maintained, and there is no directionality at the time of forming the concave portion, and mass production of the lead pin is possible. Can be improved.

In addition, the concave portion can adopt a configuration that communicates with the through hole when the lead pin is mounted in the through hole of the printed wiring board.

According to such a configuration, since the through hole can always maintain a ventilation path with the outside, the gas can be easily removed when the solder is raised, and the solder flow when the printed wiring board moves through the solder tank is improved. Since the rising path can be formed, the solder rising property with respect to the lead pin can be further improved.

As described above, according to the present invention, no special processing is required on the printed wiring board side, and the lead pins themselves can be formed with a simple structure and with high mass productivity, and the solder rising property is improved when soldering. It is possible to provide a lead pin that can reduce the occurrence of the above.

The perspective view of the lead pin which shows 1st Embodiment is shown. The schematic diagram of the mounting state to the through hole of the printed wiring board in 1st Embodiment is shown. The figure which looked at the lead pin which shows 1st Embodiment from the back surface side (concave formation side) of a printed wiring board is shown. The figure which looked at the lead pin which shows 1st Embodiment from the surface side of the printed wiring board is shown. A means for improving solderability in a conventional example will be described. A means for improving solderability in a conventional example will be described. A means for improving solderability in a conventional example will be described.

Hereinafter, the present invention will be described with reference to embodiments.
(Embodiment 1)
First, the external configuration of the lead pin 1 according to the present embodiment will be described with reference to FIG. The lead pin 1 according to the present embodiment includes a base 10 having a quadrangular cross section made of, for example, brass having conductivity, and a center portion 20 formed of the same material around the base 10.

In the longitudinal direction of the base body 10, an insertion portion 11 is provided on one side of the intermediate flange portion 102 to be inserted into a through hole formed in the printed wiring board, and the other side is exposed on the surface of the printed wiring board. An exposed portion 12 to which a lead wire or the like is connected is provided.

First, the insertion part 11 and the exposed part 12 will be described.

The insertion portion 11 is formed in a tapered shape from the middle collar portion 20 toward the tip portion, and the tip portion is formed so as to maintain a constant thickness. The taper shape improves the insertion property into the through hole, and the tip portion has a constant thickness to improve the solder fixing property.

The exposed portion 12 is formed with a constant thickness from the middle collar portion 20 to the tip portion. In addition, the thickness of the exposed portion 12 and the thickness of the root of the insertion portion 11 are formed the same on the front side and the back side of the middle collar. When the intermediate rod 20 is formed by processing the wire rod, the thickness of the insertion portion 11 and the exposed portion 12 is made the same to facilitate the processing and improve the mass productivity.

The length of the insertion portion 11 is provided about half of the length of the exposed portion 12. The length may be set to the same length depending on the state of the lead wire to be connected, or conversely, the length of the insertion portion 11 may be set to be twice the length of the exposed portion 12 or the like. .

Next, the middle collar part 20 will be described. The middle collar portion 20 protrudes from each surface so as to surround the periphery of the base body 10 and is formed in a square shape. Then, when the insertion portion 11 side is set downward and the exposed portion 12 side is set upward with respect to the middle collar portion 20, a groove shape is formed from the outer peripheral portion toward the base body 10 on the lower side in the thickness direction of the middle collar portion 20. The recesses 22a to 22d are formed. As shown in FIG. 3, the recesses 22 a to 22 d are provided at four positions perpendicular to the central portion of each surface of the base 10 having a square cross section.

Further, the groove-shaped recess is provided in a smooth curved shape in a standard normal distribution as shown in FIG. In addition, you may provide a square-wave shape in a U-shape. A circle indicated by a dotted line in FIG. 3 shows the position of the through hole 31 as a reference. As shown in FIG. 2, the shape of the groove-like recess is provided in a smooth curved shape in a standard normal distribution. In addition, you may provide a square-wave shape in a U-shape.

These recesses 22a to 22d are formed by being rotated every 90 degrees with respect to the rotation axis center when the longitudinal direction of the substrate 10 is set to the rotation axis center, and are provided in point symmetry. For this reason, since there is no directionality of a rotation direction at the time of formation of the center pin 20 and the recessed part 22 at the time of mass-producing a lead pin by processing a wire, it can produce with a sufficient yield.

FIG. 2 shows a state in which the lead pins 1 are arranged on the printed wiring board 30. The printed wiring board 30 is provided with a circular through hole 31 at a predetermined position in advance, and the insertion portion 11 of the lead pin 1 is inserted into the through hole 31 to temporarily attach the lead pin. The size of the through hole 31 is approximately the same as the length of the diagonal line of the square base of the lead pin 1, and the square corner at the base of the insertion portion 11 is the inner wall of the through hole. The lead pin is self-supporting even in a state before soldering.

When viewed from the upper side, the through hole 31 is covered with the middle collar portion 20. At this time, when the through hole 31 is closed by solder on the back surface side of the printed wiring board, the above-described sealed space appears to be generated.

However, each surface portion other than the corner portion of the base 10 is not in contact with the inner wall of the through hole 31, and four substantially bowl-shaped gap spaces are formed between the lead pin 1 and the through hole 31. In addition, since the groove-shaped recesses 22a to 22d at the four locations from the outer peripheral portion to the base 10 are formed on the lower side of the intermediate collar portion 20 so as to communicate with the gap space, The above-mentioned sealed space does not occur, and even after the solder turns to the insertion portion 11, the ventilation path is not blocked and the solder rising property can be secured well, and the occurrence of blow holes can be reduced.

In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention.

For example, the positions of the recesses provided in the middle collar portion 20 may be formed from each corner of the outer circumference of the middle collar portion 20 toward the base body 10. Compared with the case where the concave portion 22 is provided in the central portion of the middle flange portion 20, the volume of the communication portion is reduced, but the size of the gap space between the through hole 31 and the lead pin insertion portion 11 is the same, so that the expansion pressure If the same, the speed at which the air is jetted upward is increased, the solder rising property can be ensured, and the object of the present application can be achieved.

Further, the lead pin 1 is applied to a through hole provided in a printed wiring board, but may be applied to a normal pin insertion hole in a single-sided board.

DESCRIPTION OF SYMBOLS 1 Lead pin 10 Base | substrate 11 Insertion part 12 Exposed part 20 Middle collar part 21 Contact | adherence part 22 with a printed wiring board Recessed part 30 Printed wiring board 31 Through hole

Claims (3)

A lead pin with a central collar around a prismatic base,
A lead pin, wherein a concave portion is formed in the thickness direction of the center rib from the outer periphery of the center collar toward the base. The recess is
The lead pin according to claim 1, wherein the lead pin is provided point-symmetrically with respect to each surface of the base. The lead pin according to claim 1 or 2, wherein the recess communicates with the through hole when the lead pin is mounted in the through hole of the substrate.

Images