JP2007329411A - Surface-mounting circuit component mounting solder piece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-mounting circuit component to which a solder piece can be mounted for forming a solder filet for joining and fixing a lead terminal to a land pattern, and further in which the heated and melted solder piece is flown down smoothly from the lead terminal to form the solder filet. <P>SOLUTION: The surface-mounting circuit component 10 is provided with a lead terminal 12 which has: a mounting piece 13 provided with a footprint 15 joined to a land pattern 21 of a printed board 20; and a standing piece 14 standing up from the mounting piece 13. The standing piece 14 is formed with a through-hole 17 or recessed groove 18 facing the footprint 15 of the mounting piece 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface-mounted circuit component that is soldered to a printed circuit board of an electronic circuit, and more particularly to a surface-mounted circuit component that is pre-mounted with a solder piece and has excellent mountability.

  As a means for mounting circuit components typified by IC chips and transformers on a printed circuit board, there is a surface mounting method in which the footprint of the lead terminals of the circuit components is directly soldered to the land pattern of the printed circuit board. Widely done. Since the surface mounting method does not require the formation of a through hole as compared with the conventional pin mounting method, the degree of freedom in wiring to the multilayer substrate and the mounting density can be improved.

FIGS. 4A and 4B show a general mode in which conventional circuit components are surface-mounted on a land pattern. The surface-mounted circuit component 110 includes an outer case 41 that is formed in a rectangular parallelepiped shape by housing an electronic component element in a housing or resin-covered, etc., and a conductive material that is led out from the opposing side surfaces. It is usual to have a lead terminal 12. The lead terminal 12 is first led out substantially horizontally from the electronic component element, and then bent vertically downward along the side surface of the exterior case 41 to form a standing piece 14. The mounting piece 13 is formed by being bent in an L-shape toward the outside of 41 or the inside as shown in FIG.
On the printed circuit board 20 on which the circuit component 110 is mounted, a conductive land pattern 21 is provided in a size and a position including the footprint 15 of the corresponding mounting piece 13. A current is supplied to the land pattern 21 through the signal line 22.

When soldering the footprint 15 of the mounting piece 13 to the land pattern 21, the solder chip 30 is preliminarily printed and applied to the land pattern 21 through a metal mask (not shown) in order to increase the efficiency of the mounting operation. Is common ((a) in the figure).
When the circuit component 110 is placed on the printed circuit board 20 and heated through the lead terminals 12 to reflow the solder chip 30, the molten solder is interposed between the footprint 15 of the mounting piece 13 and the land pattern 21 by capillary force. Then, the two are joined together with cooling and hardening ((b) in the figure).
In this way, by forming the lead terminal 12 into an L-shaped cross section, the lead terminal 12 that supplies current to the electronic component element housed in the exterior case 41 can be surface-mounted on the conductive land pattern 21. Further, as shown in the figure, by bending the tip of the lead terminal 12 to the inside of the exterior case 41 and disposing the mounting piece 13 under the exterior case 41, the mounting area of the circuit component 110 can be reduced to the outer dimensions of the exterior case 41. Therefore, the mounting density of the circuit components 110 can be increased.

  However, with the recent increase in current and frequency of electric circuits, there is a demand for larger circuit parts for a limited mounting area, especially for coil parts such as transformers and coil antennas, and integrated circuit parts. The tendency is remarkable. Since external loads such as vibrations and shocks applied to the solder joints increase with the increase in size of the circuit components, it is necessary to improve the peel strength of the mounting pieces, particularly for the circuit components described above. For this reason, as shown in FIG. 2B, a solder fillet 32 is formed outside the lead terminal 12 having an L-shaped cross section, whereby a solder layer 31 for joining the mounting piece 13 of the lead terminal 12 and the land pattern 21 together. However, it is usual to perform reinforcement to improve the moment strength of the bent portion 16 so that the bent portion 16 is not cleaved by an external load load or the generated peel does not extend.

  However, when forming a sufficient amount of solder fillet 32 along the width direction of the lead terminal 12, the amount of solder is insufficient with only the solder chip 30 printed and applied through the metal mask. There is a problem that solder must be supplied separately. This is because the printing application of the solder chip 30 is performed uniformly and simultaneously on all of the many land patterns on which all the surface-mounted circuit components including the large-sized circuit component 110 are mounted from the viewpoint of work efficiency. This is because it is difficult to provide the thick solder chip 30 only on the land pattern 21 to which the circuit component 110 is bonded. That is, the footprint 15 of the mounting piece 13 and the land pattern 21 are joined by a part (for example, half of the total amount) of the reflow solder formed by heating the solder chip 30, and the other part (for example, the remaining half) is lead. When an attempt is made to draw out to the outside of the terminal 12 and form it into a fillet shape, the solder amount is insufficient on the whole, and a desired peel strength cannot be obtained on the mounting piece 13.

  Therefore, as an invention for making up for the above shortage of solder, the following Patent Document 1 proposes a chip type electronic component in which a solder piece for fillet formation is embedded in a lead terminal in advance. In this invention, a solder fillet is formed by providing one or a plurality of holes in the middle of a standing piece of a lead terminal and embedding a solder piece (see Patent Document 1: FIGS. 1 and 2). A sufficient amount of solder is supplied, and another solder piece is embedded in the mounting piece, so that it is not necessary to apply a solder chip to the land pattern with a metal mask.

JP 7-22277 A

However, the lead terminal described in Patent Document 1 has a problem in a mounting operation for forming a solder fillet.
That is, even if the solder piece embedded in the standing piece of the lead terminal is heated and melted, the molten solder does not flow down immediately from the hole portion toward the land pattern, but first climbs over the inner edge of the hole portion and further stands up. Because it behaves as it flows down to the land pattern below along the surface of the piece, a considerable amount of molten solder remains in the hole and on the surface of the lead terminal upright, which is cooled and re-solidified. Will be. Such residual solder and re-solidification not only impair the aesthetics of the lead terminals, but also lead to a lack of solder. For this reason, it can be said that it is extremely difficult to form a solder fillet neatly by heating and melting a solder piece embedded in the middle of a standing piece.
Therefore, when using the lead terminal described in Patent Document 1, a large amount of solder is embedded in the hole portion in advance in anticipation of the amount of solder remaining inside the hole portion or on the surface of the standing piece, or molten solder. There is a problem that a special jig device and a work process are required to scrape the wire to the outside of the lead terminal.
Further, in such lead terminals, there are molten solder that flows out of the lead terminal to form a fillet and that that flows into the lead terminal, and the latter is the exterior resin of the electronic component element. Cause the problem of heat damage.

  The present invention has been made to solve the above-described problems of circuit components having a conventional lead terminal, that is, a solder piece for forming a solder fillet for joining and fixing the lead terminal to a land pattern can be mounted. Further, it is an object of the present invention to provide a surface mount type circuit component in which a solder fillet is formed by a solder piece that has been heated and melted flowing down from a lead terminal.

In this invention, when the solder piece mounted on the vertical surface of the lead terminal is heated to become molten solder, it does not flow down on the vertical surface but comes into contact with the vertical surface from the mounted position. It was possible to reach the land pattern directly without any problems.
That is, the present invention
(1) In a surface-mounted circuit component provided with a lead terminal having a mounting piece having a footprint bonded to a land pattern of a printed circuit board and a standing piece rising from the mounting piece,
A surface-mounting circuit component, wherein the standing piece has a through hole facing the footprint of the mounting piece;
(2) In a surface-mounted circuit component provided with a lead terminal having a mounting piece having a footprint bonded to a land pattern of a printed circuit board and a standing piece rising from the mounting piece,
A surface-mounting circuit component, wherein a concave groove facing the footprint of the mounting piece is formed on the outside of the standing piece;
(3) The surface-mounted circuit component according to (1), wherein a solder piece is mounted in the through hole, or the surface-mounted circuit component according to (2), wherein a solder piece is mounted in the concave groove;
Is the gist.

In the present invention,
(4) The surface-mounted circuit component according to (1), wherein a through hole is formed across the mounting piece and the upright piece;
(5) The surface-mounted circuit component according to (2), wherein a concave groove is formed across the mounting piece and the standing piece;
(6) The surface-mounted circuit component according to (2) or (5) above, wherein the concave groove is formed by press-molding a lead terminal;
(7) The surface-mounted circuit component according to (1) or (4), wherein the through hole formed in the upright piece has a tapered shape that becomes wider toward the footprint;
(8) The surface-mounted circuit component according to the above (2), (5), or (6), wherein the concave groove formed in the standing piece has a tapered shape that becomes wider toward the footprint;
The above-mentioned problems can be solved and the object of the present invention can be achieved.

According to the surface-mounted circuit component according to the present invention (hereinafter sometimes abbreviated as “circuit component”), by providing a through hole or a concave groove in the standing piece of the lead terminal and mounting the solder piece, A sufficient amount of solder is provided to form a solder fillet without changing the thickness of the solder chip previously applied to the land pattern of the printed circuit board.
Furthermore, according to the present invention, since the through holes and concave grooves for mounting the solder pieces are provided in a mode facing the footprint of the mounting pieces, the solder pieces are melted by heating from the outside of the circuit components. The molten solder immediately flows down to the land pattern by its own weight. On the land pattern, the molten solder forms a fillet along the footprint of the mounting piece by its capillary force and surface tension.
As described above, in the present invention, since the flow of molten solder is not hindered, the solder does not remain in the through hole or the concave groove. Therefore, the mounting operation is performed efficiently, the residual solder does not impair the appearance of the circuit components, and the shape and size of the solder fillet can be formed with good reproducibility.

Hereinafter, the best mode for carrying out the present invention will be specifically described with reference to the drawings. Fig.1 (a) is a perspective view showing the lower surface side (abdominal side) of the circuit component 10 concerning 1st Embodiment of this invention, The same figure (b) is the schematic diagram showing the bb cross section. It is.
In the circuit component 10 according to the present embodiment, a through hole 17 that faces the footprint 15 of the mounting piece 13 is formed on the standing piece 14 of the lead terminal 12 with respect to the conventional circuit component 110 shown in FIG. It is characterized by being. The description of the configuration common to the conventional circuit component 110 is omitted.

  The circuit component 10 is not limited as long as it is an electronic component that is surface-mounted on a printed circuit board 20 of an electronic circuit (see FIG. 4), but for the purpose of the present invention to obtain a high mounting peel strength by a solder fillet. In view of the above, IC chip components, coil antennas, transformers, inductor components and other coil components are particularly targeted. Accordingly, examples of the electronic component element 40 accommodated in the outer case 41 include an integrated circuit and a bar core wound with a coil winding.

  The shape and number of lead terminals 12 vary depending on the type of circuit component 10. For example, when the electronic component element 40 is an integrated circuit, a plurality of strip-like lead terminals 12 corresponding to the number of signal lines are led out substantially horizontally from the opposing side surfaces of the outer case 41, and further to the outer case 41. The so-called gull wing type is generally bent downward and outward at a right angle twice. On the other hand, when the electronic component element 40 is a coil component such as a coil antenna or a transformer, the flat lead terminals 12 are led out from the outer case 41 according to the number of coil windings as shown in each drawing of FIG. The mounting piece 13 is generally bent inside the outer case 41.

  In the present embodiment, an example in which the footprint 15 of the mounting piece 13 is disposed directly below the outer case 41 is illustrated, but the present invention is not limited to this. Further, when the outer case 41 has a shape other than a rectangular parallelepiped shape such as a cylindrical shape or a hexagonal column, or when the lead terminal 12 is led out from only one side surface of the outer case 41, The present invention can also be applied to the case where it is derived from the upper surface.

  The through hole 17 which is a feature of the circuit component 10 according to the present embodiment is for mounting a solder piece for forming a solder fillet. Instead of placing the solder piece on the surface of the lead terminal 12, the solder piece is protected by the lead terminal 12 by being embedded in the through-hole 17, and the circuit component 10 is being transferred or mounted. This will not fall out.

  The through hole 17 is formed in the lower surface of the upright piece 14 of the lead terminal 12, and when viewed from the normal direction of the upright piece 14, the cross section of the mounting piece 13 and the footprint 15 are visible through the through hole 17. . That is, the shape of the through hole 17 in the plane of the upright piece 14 opens toward the footprint 15 of the lower mounting piece 13.

  The through hole 17 illustrated in FIG. 1A has an elliptical shape that extends from the standing piece 14 of the lead terminal 12 to the mounting piece 13 via the bent portion 16. The shape of the through-hole 17 is semi-elliptical (bell-shaped, inverted U-shaped), and since it opens downward in the plane of the upright piece 14, it satisfies the above requirements.

  However, the shape of the through-hole 17 is not particularly limited, and may be formed only on the upright piece 14 without straddling the mounting piece 13. In addition to the bell shape, the shape of 17 may be a semicircular shape, a rectangular shape, a triangular shape (inverted V shape), or a combination thereof.

  Further, the number of the through holes 17 may be one or plural for each lead terminal 12. In the circuit component 10 including the plurality of lead terminals 12, the shape and number of the through holes 17 provided in each lead terminal 12 may be different from each other. In the present embodiment shown in FIG. 1, three through holes 17 are formed side by side in the width direction for each lead terminal 12.

  The lead terminal 12 according to the present embodiment can be obtained, for example, by drilling three elliptical through holes side by side in a metal plate and bending the metal plate along a bending line passing through all of the three through holes. it can. In addition, the through-hole 17 may be punched after a U-shaped or L-shaped lead terminal is formed in advance by bending or cutting.

  FIG. 2A is a perspective view on the lower surface side showing a state in which solder pieces 33 are respectively mounted in the plurality of through holes 17 formed in the lead terminals 12 of the circuit component 10 according to the present embodiment. A solder piece 33 molded in the same shape is fitted and fixed to an elliptical through-hole 17 formed across the mounting piece 13 and the upright piece 14.

  Solder or cream solder can be used for the solder piece 33. These solder materials are heated in a molten or semi-molten state and poured into the through holes 17, or a solid solder material is molded in accordance with the shape of the through holes 17 and is inserted into the through holes 17. The solder piece 33 can be mounted in the through hole.

  However, in the present invention, it is not always necessary to fill the through hole 17 with the solder piece 33, and a part of the gap may be left. On the contrary, the solder piece 33 may be mounted in such a manner as to partially protrude from the through hole 17.

  The circuit component 10 according to the present invention has a through hole 17 that faces the footprint 15 of the mounting piece 13 in the standing piece 14 of the lead terminal 12. For this reason, when the circuit component 10 having the solder piece 33 mounted in the through hole 17 is joined to the printed circuit board 20 (see FIG. 4), the land pattern 21 (see FIG. 4) is located immediately below the solder piece 33. It will be. For this reason, when the solder piece 33 is heated and melted in the reflow process, the molten solder can be directly dropped from the through hole 17 to the land pattern 21 without contacting the surface of the standing piece 14.

  Moreover, about this Embodiment, the shape of the through-hole 17 in the surface of the standing piece 14 is a semi-ellipse convex upward. Thus, since the through-hole 17 formed in the standing piece 14 has a tapered shape that becomes wider downward, the reflowed solder piece 33 does not remain inside the standing piece 14. 33 can be used for forming a solder fillet without waste.

  2B, the circuit component 10 shown in FIG. 2A is placed on the printed land pattern 21 of the solder chip 30 (not shown in the figure), and the lead terminal 12 is further heated. 3 is a perspective view showing a state in which a solder layer 33 and a solder fillet 32 are formed by melting a solder piece 33 and a solder chip 30 and looking up from the lower surface side of the circuit component 10. That is, the land pattern 21 (not shown in the figure) of the printed circuit board 20 is in contact with the lower surface of the solder layer 31.

The heated and melted solder piece 33 is preferably detached from the standing piece 14 as described above and flows down to the land pattern 21, and part of the mounting piece 13 flows out of the lead terminal 12, and part of the solder piece 33 is melted. It is mixed with the solder chip 30 and developed between the footprint 15 and the land pattern 21.
The molten solder that the solder piece 33 is heated and melted and flows out to the land pattern 21 from the through hole 17 is developed in the width direction of the lead terminal 12 along the ridge line of the bent portion 16 by capillary force, and the melted solder's own weight, The solder fillet 32 is formed by the balance between the surface tension and the surface free energy with respect to the lead terminal 12.
In addition, the solder fillet 32 is cooled and hardened together with the solder layer 31 developed between the footprint 15 and the land pattern 21, and the circuit component 10 and the land pattern 21 are bonded and bonded.

  In the present invention, the use of the solder chip 30 is optional. That is, by sufficiently mounting the solder pieces 33 in the through holes 17, it is possible to eliminate the need for printing and applying the solder chips 30 with a metal mask.

  As described above, according to the circuit component 10 according to the present invention, the solder fillet 32 can be formed without forming the solder chip 30 to be printed thickly, and without separately supplying flow solder or manual solder during surface mounting. It can be suitably formed to achieve high mounting peel strength.

FIG. 3 shows a circuit component 10 according to the second embodiment of the present invention. The figure (a) is the perspective view seen from the lower surface side, The figure (b) is the bb sectional drawing.
The circuit component 10 according to the present embodiment is characterized in that a concave groove 18 is formed on the outside of the standing piece 14 of the lead terminal 12 so as to face the footprint 15 of the mounting piece 13.

  That is, instead of the through hole 17 formed in the lead terminal 12 in the first embodiment, the lead terminal 12 according to this embodiment has a groove on the opposite side of the outer case 41, that is, on the outside of the circuit component 10. 18 is formed, and a solder piece 33 (not shown in the figure) can be mounted in the concave groove 18.

  The concave groove 18 is provided in the lower surface of the upright piece 14 and opens toward the footprint 15 of the mounting piece 13. Except for the above requirements, the shape, depth, and number of the grooves 18 are not particularly limited. Further, the concave groove 18 may be formed only on the standing piece 14 or may be formed across the mounting piece 13 from the standing piece 14 via the bent portion 16. The concave groove 18 has a tapered shape in which the in-plane shape of the upright piece 14 becomes wider toward the footprint 15 as in the case of the through hole 17 of the first embodiment, so that the reflowed solder piece 33 is formed. Does not remain inside the concave groove 18 and quickly flows down toward the land pattern 21.

  In this embodiment, the concave groove 18 illustrated in FIG. 3A has a bell shape and is formed only in the surface of the upright piece 14. The lead terminal 12 having three concave grooves 18 shown side by side in the figure is formed by, for example, forming a bell-shaped concave groove 18 sideways and three bell-shaped concave grooves 18 by press-molding a metal plate, and connecting lines connecting the bottoms of the concave grooves 18. The bent portion 16 can be obtained by folding the press surface in a mountain.

Thus, by obtaining the concave groove 18 by press molding, the lead terminal 12 is formed with a convex portion 19 on the back surface of the concave groove 18, that is, on the surface facing the exterior case 41. As a result, the exterior case 41 and the lead terminal 12 are joined with the projections 19 in contact with each other as shown in FIG. In addition to avoiding contact with 41, it is also possible to avoid the risk of thermal damage to the electronic component element 40 in the filling process and reflow process of the solder pieces 33.
Furthermore, since the concave groove 18 is formed only in the plane of the upright piece 14, when the solder piece 33 mounted in the concave groove 18 is heated and melted, the amount flowing into the lower surface of the footprint 15 is suppressed, That is, a solder fillet having a size as designed can be formed between the lead terminal 12 and the land pattern 21.

(A) It is a perspective view of the surface mount type circuit component concerning 1st embodiment of this invention, (b) It is the bb sectional drawing. (A) It is a perspective view which shows the state which mounted the solder piece in the through-hole of the lead terminal. (B) It is a perspective view which shows the state in which the solder fillet was formed of the fusion | melting solder. (A) It is a perspective view of the surface mount type circuit component concerning 2nd embodiment of this invention, (b) It is the bb sectional drawing. (A) It is a perspective view which shows the conventional surface mount type circuit component and a printed circuit board. (B) It is a perspective view which shows the state which joined the conventional surface mount type circuit component to the printed circuit board, and formed the solder fillet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,110 Circuit component 12 Lead terminal 13 Mounting piece 14 Standing piece 15 Footprint 16 Bending part 17 Through-hole 18 Concave groove 19 Convex part 20 Printed circuit board 21 Land pattern 22 Signal line 30 Solder chip 31 Solder layer 32 Solder fillet 33 Solder Piece 40 Electronic component element 41 Exterior case

Claims (3)

In a surface-mounted circuit component provided with a lead terminal having a mounting piece having a footprint bonded to a land pattern of a printed circuit board and a standing piece rising from the mounting piece,
A surface-mounted circuit component, wherein the standing piece is formed with a through hole facing a footprint of the mounting piece. In a surface-mounted circuit component provided with a lead terminal having a mounting piece having a footprint bonded to a land pattern of a printed circuit board and a standing piece rising from the mounting piece,
A surface-mounted circuit component, wherein a concave groove facing the footprint of the mounting piece is formed outside the standing piece.   The surface-mounted circuit component according to claim 1, wherein a solder piece is mounted in the through hole, or the surface-mounted circuit component according to claim 2, wherein a solder piece is mounted in the concave groove.

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