JP4712509B2 - Relay fixing structure - Google Patents

Description

  For example, the present invention relates to a relay fixing structure in which a relay is fixed to a circuit board used for an electric junction box of an automobile.

Conventionally, various relay fixing structures have been proposed (see, for example, Patent Document 1).
As shown in FIG. 3, the conventional relay fixing structure 10 includes a relay body 2 having a relay body 2a, a terminal 4 and a leg 6 extending and fixed to the lower portion of the relay body 2a. The terminal 6 is made to stand, the terminal 4 is inserted into the through hole 7 of the circuit board 3, and the terminal 4 is fixed in the through hole 7 with solder 5.
Conventionally, the leg portion 6 is at most about 0.4 to 0.5 mm in height, and the solder is eutectic solder. In the figure, reference numeral 5a denotes a fillet of solder 5 formed on the surface opposite to the relay 2 fixing surface.

JP-A-10-255626

However, in recent years, lead-free solder has been used instead of eutectic solder for environmental measures.
When the present inventors formed the conventional relay fixing structure 10 shown in FIG. 3 using lead-free solder, the solder 5 is not sufficiently filled into the through hole 7 during flow soldering, and the solder 2 is fixed on the fixing surface side. 5 fillet was not formed, resulting in a problem of poor connection.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a relay fixing structure that can prevent poor connection when a relay is fixed on a circuit board even when lead-free solder is used.

According to a first aspect of the present invention, there is provided a relay fixing structure in which a relay having a relay main body, a terminal extending and fixed to a lower portion of the relay main body, and a leg is made to stand on the circuit board by the leg. , the terminal is inserted into the through hole of the circuit board by flow soldering process from the opposite side of the relay, a relay fixing structure fixing the said terminal in the through hole, wherein the solder is lead-free solder, In the state where the relay main body is made to stand on the circuit board by the leg, the leg portion improves the escape of gas from the through hole to the relay fixing surface in the flow soldering process, and the circuit board. of 0.9mm or more intervals to allow the formation of a fillet on the relay fixing surface side formed to a length to be formed between the relay main body and the circuit board, the terminals, the leg And forming the above length, characterized in that the pre-solder surface formed from the tip to the vicinity tip corresponding position of the legs.

  ADVANTAGE OF THE INVENTION According to this invention, even when lead-free solder is used, the relay fixing structure which can prevent the connection failure when a relay is fixed on a circuit board can be provided.

1A and 1B show a relay fixing structure 1 according to an embodiment of the present invention and a manufacturing process thereof.
First, as shown in FIG. 1A, a relay 2 and a circuit board 3 are prepared.
The relay 2 includes a relay body 2a, a terminal 4 that extends and fixed to the lower portion of the relay body 2a, and a leg 6. Here, the leg portion 6 has a length of about 1.0 mm, and the terminal 4 has a length of about 4 mm. The leg 6 is preliminarily formed with a surface of pre-solder 8 in a range of about 2 mm to 3 mm from the tip (a range from the tip to the position corresponding to the tip of the leg).

Through holes 7 are formed in the circuit board 3 so as to penetrate the front and back surfaces. The through hole 7 is formed with a copper plating portion (not shown).
As shown by the arrow in FIG. 1A, such a relay 2 is made to stand on a circuit board 3 with legs 6, and a terminal 4 on which a preliminary solder 8 is formed is inserted into a through hole 7 of the circuit board 3. 1b, the terminal 4 is inserted into the through hole 7, and the solder 5 made of lead-free solder is fixed from the opposite side of the bottom surface of the two relays by flow soldering, thereby fixing the relay. 1 is configured.
At this time, the solidified solder 5 has fillets 5 a and 5 b formed on both the front and back surfaces of the circuit board 3, and no void remains inside the through hole 7.

The process of completing the relay fixing structure 1 of the present embodiment will be described.
As a result of the study, the present inventor has found that the gap between the relay body 2a and the circuit board 3 is too close in the configuration of FIG. It was considered that the lead-free solder with poor quality did not sufficiently fill the through hole 7 with the solder 5 during flow soldering.
Therefore, first, as shown in FIG. 1 (b), the above-described gas escape is improved by setting the distance H between the relay main body 2a and the circuit board 3 to about 0.9 mm or more.
Further, by widening the interval H in this way, the fillet 5b of the solder 5 can be formed on the fixing surface side of the relay 2 as shown in FIG. 1B, so that the fixing strength is improved.
However, it has been clear by the inventor's examination that the solder 5 is not sufficiently raised only by increasing the distance H as described above.
Therefore, in the present embodiment, as shown in FIG. 1A, preliminary solder 8 is applied to the surface of the terminal 4 before the relay 2 is fixed to the circuit board 3. The range of the preliminary solder 8 is made as wide as possible from the front end to the vicinity of the front end corresponding position of the leg portion 6 so that the solder 5 is lifted up. The preliminary solder 8 is preferably lead-free solder from the viewpoint of preventing cracking of the solder 5 formed on the surface.

Here, it is difficult to form the preliminary solder 8 up to the vicinity of the tip corresponding position of the leg 6 with the configuration of FIG. Because the tip of the leg 6 is too close to the relay main body 2a, when the preliminary solder 8 is formed, the molten preliminary solder 8 hits the relay main body 2a and adversely affects the relay main body 2a. Because there is a possibility.
On the other hand, in this embodiment, since the distance H between the relay main body 2a and the circuit board 3 is increased, it is possible to widen the range of the preliminary solder 8 and to form the leg 6 near the tip corresponding position. It is possible.
Such a large interval H not only improves the escape of gas, but also forms a solder fillet on the surface on the relay 2 side, lengthens the terminal 4, and widens the range of the preliminary solder 8. Is taken into consideration.

  By adopting such a relay fixing structure 1 of the present embodiment, even when lead-free solder is used as the solder 5, the gas between the relay body 2 a and the circuit board 3 during the flow soldering process. The solder 5 is sufficiently pulled out and the solder 5 is sufficiently lifted, so that the solder 5 is sufficiently filled in the through hole 7 and no voids are formed. Therefore, the relay 2 and the circuit board 3 are fixed by the solder 5. Becomes strong.

FIG. 2 shows a relay fixing structure 1 according to the second embodiment of the present invention.
As shown in FIG. 2, instead of providing the leg portion 6, the protruding portion 4 a may be formed on the terminal 4, and the interval H may be regulated by preventing the portion from entering the through hole 7.
In this case, since it is not necessary to provide the leg part 6, it is preferable in terms of cost.
In the present invention, the upper limit value of the distance H between the relay body 2a and the circuit board 3 is not particularly limited, but is preferably 3 mm or less in consideration of the stability of the fixed state of the relay 2.

It is a partial side sectional view showing the relay fixing structure of the first embodiment of the present invention. It is a partial side sectional view showing the relay fixing structure of the second embodiment of the present invention. It is a partial side sectional view showing a conventional relay fixing structure.

DESCRIPTION OF SYMBOLS 1 Relay fixing structure 2 Relay 2a Relay main-body part 3 Circuit board 4 Terminal 4a Overhang | projection part 5 Solder 5a, 5b Fillet 6 Leg part 7 Through hole 8 Pre-solder 10 Relay fixing structure (conventional)

Claims (1)

A relay having a relay body portion and said relay body lower portion extending fixed pins and the legs, is standing with the leg portion on the circuit board, is inserted the pin into the through hole of the circuit board, the relay by flow soldering process from the opposite side of, a relay fixing structure fixing the said terminal in the through holes,
The solder is lead-free solder,
The legs,
In the state where the relay main body is made to stand on the circuit board with the leg part, it is possible to improve the escape of gas from the through hole to the relay fixing surface side in the flow soldering process, and to the relay fixing surface side of the circuit board Forming a distance of 0.9 mm or more allowing the formation of fillets between the relay body and the circuit board,
The relay fixing structure in which the terminal is formed to have a length longer than that of the leg, and preliminary solder is formed on the surface from the tip of the terminal to the vicinity of the tip corresponding position of the leg.

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