JP2017041576A - Structure for soldering terminal to through-hole, and soldering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for soldering a terminal to a through-hole in which a paste solder can be prevented from being interrupted or divided by reducing an extrusion amount of the paste solder during terminal insertion and a wetting defect of the solder in a reflow soldering step can be prevented by satisfactorily depositing the paste solder to the terminal.SOLUTION: In a structure where a distal end portion 10a of a rod-shaped terminal 10 is inserted into a through-hole 2 filled with a paste solder 50 and the terminal 10 is soldered to the through-hole 2 through a reflow soldering step, in the distal end portion of the terminal 10, a tapered part 12 of a predetermined length T1 is formed of which the cross-sectional area becomes smaller gradually from a side of a proximal end 12b to a distal end 12a When inserting the terminal 10 into the through-hole 2, the distal end 12a of the tapered part 12 penetrates outside of the through-hole 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a terminal soldering structure and a soldering method for a through hole of a circuit board.

  When mounting a surface-mounted component on a circuit board, as shown in FIG. 5, paste solder (also referred to as cream solder) 50 is filled in the through hole 2 formed in the circuit board 1 by a technique such as screen printing. The circuit conductor 3 that forms the through-hole 2 by passing through a reflow soldering process with the terminal 110 of the surface-mounted component 100 (electrical component such as an electronic component or a connector) inserted into the through-hole 2. It is generally performed to connect to (for example, see Patent Document 1).

  The reflow soldering step is a step of performing soldering by applying paste solder 50 on the circuit board 1 and then heating it with hot air or the like.

  Specifically, in this reflow soldering process, the paste solder is partially applied to the surface of the circuit board and the inside of the through hole by a screen printing technique, and the terminal of the mounting component is inserted into the through hole. Then, with the paste solder attached to the tip of the terminal, hot air is blown onto the circuit board in a reflow furnace to heat the terminal. This is a soldering process in which the paste solder is melted inside the through hole using the heat received by the terminal at this time, thereby electrically connecting the terminal and the through hole.

  Normally, the terminal 110 to be inserted into the through hole 2 has a slightly narrow tip for facilitating insertion into the through hole 2 of the circuit board 1, but generally has a constant diameter (that is, a constant cross-sectional area). ) Straight shape. In FIG. 5, the code | symbol 111 shows the straight shape part of a fixed diameter, and the code | symbol 112 shows the taper shape part by chamfering.

  By the way, in such a shape of the terminal 110, as shown in FIG. 6, when the tip of the terminal 110 is inserted into the through hole 2, the paste solder 50 previously filled in the through hole 2 is replaced with the through hole 2. Since the amount pushed out increases and the diameter of the terminal 110 is constant, as the insertion of the terminal 110 proceeds, the paste solder 50 cannot follow the movement of the straight-shaped portion 111, and the solder 50 is interrupted and divided. There is a problem that it is easy to do.

  For example, if there is a portion 57 where the solder 50 is cut off and divided, the solder reflow soldering process deteriorates the solder wetting (a phenomenon that rises along the terminal to form the fillet), and clean fillets 58 and 59 are formed. This may cause a connection failure.

  This point will be described in detail with reference to FIGS.

  As shown in FIGS. 7 and 8, when the terminal 110 is inserted into the through hole 2 of the circuit board 1 filled with a sufficient amount of paste solder 50 in advance as shown by the arrow, the tip surface of the terminal 110 is moved. Thus, the paste solder 50 in the through hole 2 is gradually pushed out toward the opposite surface side of the circuit board 1.

  Further, when the terminal 110 is inserted, as shown in FIG. 9, a large amount of paste solder 50 is pushed out by the terminal 110, and the pushed-out solder 55 is drawn into the terminal 110 and sinks downward.

  In this way, the paste solder 50 positioned around the terminal 110 also tries to go out of the through hole 2 in such a manner that it is dragged by the solder 55 pushed out by the tip surface of the terminal 110.

  When the straight-shaped portion 111 moves in the terminal insertion direction, the paste solder 50 positioned around the terminal 110 is not particularly restrained in addition to the viscous force of the paste solder itself. The paste solder 50 located in the position is pulled out without much resistance and tries to go out of the through hole 2. As a result, the paste solder 50 located around the terminal 110 is likely to generate a portion 57 that is interrupted and divided at the front end surface of the terminal 110.

  If the paste solder 50 has a discontinuous part 57, the amount of solder necessary for reflow soldering is reduced, and the paste solder 50 extruded by the terminal 110 may not be wetted up. Since the amount of the paste solder 50 remaining is small, the solder reflow soldering process makes the solder wetting very bad and may cause a connection failure.

JP 2005-26456 A

  As described above, conventionally, the shape of the terminal 110 inserted into the through-hole 2 is a straight shape having a substantially constant diameter (a constant cross-sectional area) from the distal end to the proximal end. The extrusion amount of the paste solder 50 when inserted was increased. Further, when the terminal 110 is inserted, the amount of extrusion increases, and the paste solder 50 is likely to be broken or divided, and as a result, the total solder amount is reduced in the reflow soldering process. The solder wettability worsened and it was easy to cause poor connection.

  In consideration of the above circumstances, the present invention can reduce the amount of paste solder extruded when a terminal is inserted into a through-hole to prevent breakage or breakage of the solder, and to adhere paste solder to the terminal well. As a result, it is possible to prevent solder wetting-up failure in the reflow soldering process, and as a result, it is possible to guarantee a good joint quality and soldering structure and soldering of the terminal to the through hole It aims to provide a method.

  In order to solve the above-mentioned problem, the terminal soldering structure for the through-hole according to the first aspect of the present invention is the tip of the rod-shaped terminal provided in the electrical component in the through-hole of the circuit board previously filled with paste solder. In this state, through a reflow soldering process, in the terminal soldering structure for the through hole in which the terminal is soldered to the through hole, the distal end of the terminal goes from the proximal end to the distal end. A taper portion having a predetermined length that gradually decreases in cross-sectional area is formed, and when the terminal is inserted into the through hole, the tip of the taper portion penetrates outside the through hole. .

  In the soldering method of the terminal to the through hole according to the second aspect of the present invention, paste solder is filled in the through hole of the circuit board, and the tip of the rod-shaped terminal provided on the electrical component is inserted into the through hole. In the soldering method of the terminal to the through hole for soldering the terminal to the through hole by passing through a reflow soldering step, the cross-sectional area gradually increases from the base end side to the tip end of the terminal. A state in which a tapered portion having a predetermined length is formed to be small, and when the tip end portion of the terminal is inserted into the through hole, the tip end of the taper portion penetrates the through hole, and the terminal is held in the penetrated state. Thus, the terminal is soldered to the through-hole through the reflow soldering step.

  According to the first aspect of the present invention, the tapered portion is formed at the tip of the terminal inserted into the through hole, and the tip of the tapered portion penetrates out of the through hole when the terminal is inserted into the through hole. Therefore, the amount of paste solder extrusion (displacement amount) when the terminal is inserted into the through hole can be reduced by the reduction of the terminal volume compared to the conventional straight section alone. The amount of paste solder remaining in the through hole can be increased.

  Further, when the tapered portion is inserted into the through hole, a component force and a reaction force in a direction orthogonal to the terminal insertion direction can be generated in the paste solder in the through hole by the inclined surface of the tapered portion. Accordingly, the adhesive strength of the paste solder to the surface of the terminal and the inner wall surface of the through hole can be increased, and the amount of the paste solder that is dragged by the paste solder pushed out of the through hole by the tip surface of the inserted terminal and leaks to the outside Can be reduced. Accordingly, the paste solder can be uniformly attached to the terminals without being interrupted or divided. As a result, it is possible to prevent a solder wetting failure in the reflow soldering process and to obtain a good solder joint state in which sufficient fillets are formed both above and below the through hole.

  According to the invention of claim 2, a tapered portion having a predetermined length is formed at the tip of the terminal to be inserted into the through hole, and the tip of the tapered portion is inserted when the terminal is inserted into the through hole filled with paste solder. Since it is inserted into the through hole and soldered in the reflow soldering process while maintaining the state, the terminal is passed through by the amount of decrease in the terminal volume compared to the conventional straight section only. The amount of paste solder pushed out (insertion amount) when inserted into the hole can be reduced, and the amount of paste solder remaining in the through hole can be increased.

  In addition, when inserting the taper portion into the through hole, the inclined surface of the taper portion can cause a component force in the direction perpendicular to the terminal insertion direction and the reaction force to the paste solder in the through hole. The adhesive strength of the paste solder to the surface of the metal and the inner wall surface of the through hole can be increased. Therefore, it is possible to reduce the amount of paste solder that is dragged by the paste solder pushed out from the through hole by the tip surface of the terminal to be inserted and leaks to the outside, and the paste solder is evenly attached to the terminal without being interrupted or divided. be able to. As a result, it is possible to prevent a solder wetting failure in the reflow soldering process and to obtain a good solder joint state in which sufficient fillets are formed both above and below the through hole.

It is sectional drawing which shows the soldering structure of the terminal with respect to the through hole of embodiment of this invention. It is explanatory drawing of the soldering method for obtaining the soldering structure of the terminal with respect to the through hole of embodiment of this invention, and is sectional drawing which shows the state before inserting a terminal in a through hole. It is explanatory drawing of the soldering method for obtaining the soldering structure of the terminal with respect to the through hole of embodiment of this invention, and is sectional drawing which shows a state when it starts to insert a terminal into a through hole. It is explanatory drawing of the soldering method for obtaining the soldering structure of the terminal with respect to the through hole of embodiment of this invention, and is sectional drawing which shows the state before finishing inserting a terminal to an insertion completion position in a through hole. It is sectional drawing which shows the structure where the terminal of the conventional electrical equipment was soldered to the through hole. It is sectional drawing which shows the soldering structure of the terminal with respect to the conventional through hole. It is explanatory drawing of the soldering method for obtaining the soldering structure of the terminal with respect to the conventional through hole, and is sectional drawing which shows the state before inserting a terminal in a through hole. It is explanatory drawing of the soldering method for obtaining the soldering structure of the terminal with respect to the conventional through hole, and is sectional drawing which shows a state when it begins to insert a terminal in a through hole. It is explanatory drawing of the soldering method for obtaining the soldering structure of the terminal with respect to the conventional through hole, and is sectional drawing which shows the state before finishing inserting a terminal to an insertion completion position in a through hole.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 is a cross-sectional view showing a soldering structure of a terminal to a through hole according to the embodiment, FIGS. 2 to 4 are explanatory diagrams of a procedure (soldering method) for obtaining the soldering structure of FIG. FIG. 3 is a cross-sectional view showing a state before the terminal is inserted into the through hole, FIG. 3 is a cross-sectional view showing a state when the terminal is started to be inserted into the through hole, and FIG. It is sectional drawing which shows the previous state.

  The rod-shaped terminal 10 of the electrical component used in this embodiment has a circular or polygonal cross-sectional shape, and the distal end portion 10a inserted into the through hole 2 of the circuit board 1 is closer to the distal end from the proximal end side. The taper portion 12 has a gradually decreasing cross-sectional area. The through hole 2 is formed in a part of the circuit conductor 3 on the circuit board 1.

  The tapered portion 12 provided at the distal end portion 10a of the terminal 10 is formed in a truncated cone shape when the sectional shape of the terminal 10 is circular, and a polygonal frustum when the sectional shape of the terminal 10 is polygonal (for example, rectangular). It is formed in a shape (for example, a quadrangular pyramid shape). The distal end 12a of the tapered portion 12 is coincident with the distal end of the terminal 10, and the proximal end 12b of the tapered portion 12 is continuous with the straight portion 11 having a constant cross-sectional area.

  Then, with the length T1 of the taper portion 12 in a state where the terminal 10 is inserted into the through hole 2 to the proper position, a partial length range T2 on the proximal end side of the taper portion 12 remains in the through hole 2. It is set to such a dimension.

  The tip portion 10a of the terminal 10 configured in this way is inserted into the through hole 2 of the circuit board 1 filled with the paste solder 50 in advance, and in this state, the terminal 10 passes through the through hole by passing through a reflow soldering process. 2 is soldered.

  Next, a procedure (soldering method) for obtaining the soldering structure having the configuration shown in FIG. 1 will be described.

  First, as shown in FIG. 2, the paste solder 50 is filled in the through hole 2 of the circuit board 1 by a method such as screen printing.

  Then, the terminals 10 are inserted into the through holes 2 of the circuit board 1 filled with a sufficient amount of paste solder 50 in advance, as indicated by arrows in FIGS.

  Then, as the tip end surface of the terminal 10 moves, the paste solder 50 in the through hole 2 is gradually pushed out toward the opposite surface side of the circuit board 1, and the pushed-out solder 55 is drawn into the terminal 10. Go down and go down.

  At the time of this insertion, as shown in FIG. 1, the terminal 10 is inserted to a position where a part on the base end 12b side of the tapered portion 12 stays in the through hole 2, and the reflow soldering process is performed while maintaining this state. Solder with.

  That is, the terminal 10 is passed through the through-hole 2 until the tip 12a of the tapered portion 12 penetrates the through-hole 2 and a portion of the tapered portion 12 on the base end 12b side (the range of the length T2) stays in the through-hole 2. Insert into 2. Usually, since some means for restricting the insertion amount of the terminal 10 is provided, the above state is automatically obtained by inserting the terminal 10 to the insertion restriction position (insertion completion position).

  The terminal 10 can be soldered to the through hole 2 by performing a reflow soldering process in a state where the terminal 10 is held at this position.

  In the soldering structure and soldering method of this embodiment, the tapered portion 12 having a predetermined length T1 is provided at the tip portion 10a of the terminal 10, so that the terminal volume is reduced as compared with the conventional straight portion alone. As a result, the amount of paste solder 50 to be pushed out (the amount of displacement) when the terminal 10 is inserted into the through hole 2 can be reduced, and the amount of paste solder 50 remaining in the through hole 2 can be increased.

  2 and 3, when the taper portion 12 is inserted into the through hole 2, the inclined surface of the taper portion 12 causes the paste solder 50 in the through hole 2 to be perpendicular to the terminal insertion direction. It is possible to generate a component force and a reaction force thereof. Therefore, the adhesion of the paste solder 50 to the surface of the terminal 10 and the inner wall surface of the through hole 2 can be increased.

  Therefore, it is possible to reduce the amount of paste solder 50 that is dragged to the paste solder 50 pushed out from the through hole 2 by the tip surface of the terminal 10 to be inserted and leaks to the outside, and the paste solder 50 is interrupted or divided. Without being attached to the terminal 10.

  This can be maintained even when the insertion of the terminal 10 into the through hole 2 is completed by leaving a part of the proximal end side of the tapered portion 12 in the through hole 2.

  As a result, it is possible to prevent the solder wetting failure in the reflow soldering process, and to obtain a solder joint structure having good (sufficient) fillets 51 and 52 on both the upper and lower sides of the through hole 2 as shown in FIG. be able to.

  Further, if the length T1 of the tapered portion 12 is formed longer than the depth of the through hole 2, the base end 12b of the tapered portion 12 is positioned above the through hole 2 when the terminal 10 is inserted into the through hole 2. Even though the straight portion 11 on the upper side (base end 12b side) of the tapered portion 12 does not reach the through hole 2, the through hole 2 is formed by the distal end surface of the terminal 10 to be inserted, as in the case shown in FIG. The amount of the paste solder 50 that is dragged by the paste solder 50 that is pushed out from the terminal and leaks to the outside can be further reduced, and the long taper portion of the terminal 10 can be obtained without interrupting or dividing the paste solder 50. 12 can be evenly attached. As a result, it is possible to prevent poor solder wetting in the reflow soldering process, and to obtain a solder joint structure in which good fillets are formed on the top and bottom of the through hole 2.

DESCRIPTION OF SYMBOLS 1 Circuit board 2 Through hole 10 Terminal 10a Tip part 11 Straight part 12 Tapered part 12a Tip 12b Base end 50 Paste solder T1 Length of taper part

Claims (2)

Insert the tip of the rod-shaped terminal provided on the electrical component into the through-hole of the circuit board filled with paste solder in advance, and in this state, reflow soldering process, the terminal is soldered to the through-hole In the soldering structure of the terminal to the attached through hole,
A tapered portion having a predetermined length that gradually decreases in cross-sectional area from the proximal end side toward the distal end is formed at the distal end portion of the terminal, and when the terminal is inserted into the through hole, the distal end of the tapered portion is A terminal soldering structure for a through hole, characterized in that it penetrates outside the through hole. The through hole of the circuit board is filled with paste solder, and the tip of the rod-like terminal provided on the electrical component is inserted into the through hole. In this state, the terminal is passed through the reflow soldering process. In the soldering method of the terminal to the through hole soldered to the hole,
A tapered portion having a predetermined length that gradually decreases in cross-sectional area from the proximal end side to the distal end is formed at the distal end portion of the terminal, and when the distal end portion of the terminal is inserted into the through-hole, A terminal with respect to a through hole, wherein a tip penetrates the through hole, and the terminal is soldered to the through hole by passing through the reflow soldering process in a state where the terminal is held in the penetrated state. Soldering method.

Images