JP3901625B2 - Bonding structure of chip parts to bus bar - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a structure for joining chip parts to a bus bar which is joined on an electronic part mounted on a wiring board, inside a connector, and further on J / B or the like.
[0002]
[Prior art]
As shown in FIG. 6, the electronic component 1 is composed of four bus bars 2, 3, 4 and 5, and the bus bars 3, 4, 5 arranged in parallel are orthogonal to the one bus bar 2, Arranged in isolation. That is, with the bus bar 2 in common, a total of three chip components 6, 7, and 8 are mounted between the bus bar 2 and the bus bar 3, between the bus bar 2 and the bus bar 4, and between the bus bar 2 and the bus bar 5. The
The chip parts 6, 7, and 8 are parts such as capacitors, resistors, transistors, and diodes. In the illustrated example, the chip component 6 is a capacitor, and the chip components 7 and 8 are resistors.
[0003]
Further, recessed solder lands 10, 11, 12, 13 are formed at positions where chip components formed in a chip shape are soldered. The solder lands 10, 11, 12, and 13 are formed in a region corresponding to a desired appropriate solder wet area.
[0004]
Next, referring to FIGS. 7 and 8, molten solder is dropped into the gap between the connection portion 6 t and the solder land 10 in a state where the connection portion 6 t of the chip component 6 is isolated from the inner end edge of the solder land 10. Apply. By solidification of the molten solder, the chip component 6 can be soldered to the bus bars 2, 3, 4, and 5 via the connection portion 6t and the solder land 10 (see Japanese Patent Application No. 2001-318133).
[0005]
In addition, when soldering a diode chip to a metal plate (conductor piece) in the conventional soldering structure, a large number of grid-like or radial fine grooves are formed on the soldering surface of the metal plate, resulting in excessive soldering. The solder was absorbed into the narrow groove by capillary action to prevent the excess solder from protruding (see, for example, Patent Document 1 below).
In addition, in the diode built-in connector, by providing a joint portion having a plurality of through holes formed in the connecting conductor piece, and soldering the substantially joint portion and the diode chip, the excess solder is absorbed into the through hole, Some have prevented solder from protruding (see, for example, Patent Document 2 below).
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-27675 (page 3, FIG. 1)
[Patent Document 2]
JP-A-9-106860 (second page, FIG. 1)
[0007]
[Problems to be solved by the invention]
However, as shown in FIG. 8, when soldering the chip components 6, 7, 8, there is a problem that voids (bubbles) 16 are formed in the thick portion of the solder fillet 15. The formation of the void 16 reduces the strength of the soldered portion.
Further, if the amount of solder is reduced in order to reduce the void 16, an appropriate solder fillet shape cannot be obtained, and there is a problem that the reliability of soldering is lowered.
Further, according to the technique disclosed in Patent Document 1 and the like, although solder protrusion can be prevented, an apparatus and method for preventing void formation are not disclosed.
[0008]
SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and it is possible to prevent the formation of voids in a solder fillet and maintain a sufficient solder joint strength, thereby realizing a highly reliable solder joint chip bar bus bar joint structure. The purpose is to provide.
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a structure for joining chip parts to a bus bar, wherein one or more electronic circuit chip parts are mounted on a bus bar, which is two or more bar-shaped metal conductors to be isolated, and the chip parts are connected. The chip part is joined to the bus bar, and the chip part is surrounded by a solder land formed as a recess at a predetermined position on the surface of the bus bar where the solder fillet is formed. As described above, a protrusion is provided.
[0010]
According to the joining structure of the chip component with the above structure to the bus bar, the amount of solder used is reduced, and the generation of voids is reduced. Therefore, the strength of the soldered portion is improved, and the reliability of solder joint can be increased. In addition, the positioning performance when chip components are mounted is improved.
[0011]
The joining structure of the chip part to the bus bar according to claim 2 of the present invention is characterized in that the cross-sectional shape of the protrusion is a right triangle shape. It is.
[0012]
According to the bus bar joining structure of the chip part having the above-described configuration, the bus bar material is interposed in the solder fillet by providing the projection with a simple triangular cross-sectional shape. The same solder fillet shape can be secured. Therefore, since it becomes possible to solder with a small amount of solder, the amount of voids is relatively reduced.
[0013]
According to a third aspect of the present invention, in the joining structure of the chip part to the bus bar, the protrusion is formed simultaneously with the solder land by pressing. It is a junction structure.
[0014]
According to the joining structure of the bus bars of the chip parts having the above-described structure, it is formed by pressing at the same time as the solder land on which the fillet is formed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a structure for joining chip parts to a bus bar according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a perspective view of a bus bar and a chip component immediately before solder bonding of the bonding structure of the chip component to the bus bar of the present embodiment, FIG. 2 is a cross-sectional view taken along line BB in FIG. 1, and FIG. It is an expanded sectional view of a projection part.
FIG. 4 is an exploded perspective view after press working showing the method of joining the chip component to the bus bar according to the present embodiment, FIG. 5 shows the procedure for joining the chip component to the bus bar, and FIG. (B) is a perspective view in which chip parts are arranged, and (c) is a perspective view showing a state in which a solder fillet is formed.
[0016]
As shown in FIG. 1, a chip component such as a resistor or a capacitor is soldered to an electronic component 1, and a termination resistor circuit provided at the end of a bus line laid in an automobile or the like is formed into a compact chip shape. It is the formed subassembly.
In the illustrated electronic component 1, the bus bars 3 arranged in parallel are arranged so as to be orthogonal to one bus bar 2. A chip component 6 is mounted between the bus bar 2 and the bus bar 3.
[0017]
The chip component 6 includes a connecting portion 6t exposed on the bus bars 2 and 3 side. These connecting portions 6t are connected to solder lands 10 and 11 provided on the bus bars 2 and 3, respectively. The connection portion 6t is formed in a flat plate shape on both sides of the chip component 6, and the lower surface facing the bus bars 2 and 3 forms part of the bottom surface of the chip component 6.
Further, the lower surface of the connection portion 6t extends to face the inside of the chip component 6. The connecting portion 6t is preferably made of a copper alloy having at least a surface excellent in solder wettability.
[0018]
The bus bars 2 and 3 of the present embodiment are provided with protrusions 20 so as to surround the chip component 6 on solder lands 10 and 11 formed as recesses at predetermined positions on the surface thereof.
As shown in FIG. 2, the cross-sectional shape of the protrusion 20 is preferably a right triangle.
[0019]
That is, as shown in FIG. 3, since the cross-sectional shape is a right triangle, the distance a between the hypotenuse 21 and the outer surface 22 of the solder fillet 15 in the cross-sectional shape, the side 23 upright from the bottom surface, and the chip component 6 The distance b between the connecting portion 6t (see FIG. 1) is substantially equal.
Therefore, the thickness of the solder fillet 15 can be kept substantially uniform, soldering can be performed with a small amount of solder, and the amount of voids is relatively reduced.
[0020]
Next, a method of joining the chip component 6 to the bus bars 2 and 3 according to the present invention will be described with reference to FIGS. 4 and 5A to 5C.
First, as shown in FIG. 4, the solder lands 10, 11 in the recesses are disposed at the positions where the chip components 6 formed in a chip shape are soldered, and the protrusions 20 surround the chip components 6 in the solder lands 10, 11. Are simultaneously formed by the press 30.
[0021]
Next, as shown in FIG. 5A, solder paste 31 is printed on the solder lands 10 and 11, respectively.
[0022]
Next, as shown in FIG. 5 (b), the connection part 6 t of the chip component 6 is mounted on the solder paste 31 inside the protrusion 20 in the solder lands 10 and 11.
Next, as shown in FIG. 5C, molten solder is applied dropwise to the gap between the connecting portion 6t and the solder lands 10 and 11 in this state. The chip component 6 can be soldered to the bus bars 2 and 3 by solidification of the molten solder.
At this time, the molten solder dripping amount may be a minimum appropriate amount, and a fillet (filled solder) is formed between the solder lands 10 and 11 where the protrusions 20 are formed and the connection portion 6t.
The semi-assembly of the bus bars 2 and 3 and the chip component 6 described above is used as a chip-shaped electronic component by molding the peripheral portion of the chip component 6 with a synthetic resin material.
[0023]
According to the joining structure of the bus bars 2 and 3 of the chip component 6 having the above-described configuration, a part of the bus bars 2 and 3 is interposed in the solder fillet 15 by providing the projections 20 having a simple triangular cross-sectional shape. Thus, a solder fillet shape equivalent to the conventional one can be secured with a small amount of solder. Therefore, since the chip component 6 can be soldered with the minimum appropriate amount of solder, the amount of voids can be reduced.
Further, positioning at the time of mounting the chip parts becomes easy, and workability can be improved.
[0024]
The joining structure of the chip component to the bus bar of the present invention is not limited to the above embodiment. For example, although the cross-sectional shape of the protrusion 20 described above has been described as a triangular shape, the upper end of the protrusion 20 is rounded as long as it does not interfere with the press processing with the solder lands 10 and 11. Or may have any other cross-sectional shape.
[0025]
【The invention's effect】
As described above, according to the joining structure of the chip component to the bus bar according to the first aspect of the present invention, the chip component is placed on the solder land formed as a recess at a predetermined position on the surface of the bus bar where the solder fillet is formed. Since the projecting portion is provided so as to surround the chip component, the chip component can be soldered with the minimum appropriate amount of solder, and the generation of voids can be reduced. Therefore, the formation of voids in the solder fillet is prevented to maintain a sufficient solder joint strength, thereby realizing a highly reliable solder joint.
[Brief description of the drawings]
FIG. 1 is a perspective view of a bus bar and a chip component immediately before solder bonding of a bonding structure of a chip component to a bus bar according to the present invention.
FIG. 2 is a cross-sectional view taken along line BB in FIG.
FIG. 3 is an enlarged view of a protrusion in FIG.
FIG. 4 is an exploded perspective view after press working showing a method for joining chip parts to a bus bar according to the present embodiment.
5A and 5B show a procedure for joining chip parts to a bus bar according to the present embodiment, in which FIG. 5A is a perspective view after applying a solder paste, and FIG. 5B is a perspective view showing a state in which chip parts are mounted thereon; (C) is a perspective view showing that a solder fillet has been formed.
FIG. 6 is a perspective view of an assembly showing a solder joint state between a conventional chip component and a bus bar.
7 is an enlarged partial perspective view showing a solder joint portion between the chip part and the bus bar in FIG. 6. FIG.
FIG. 8 is a cross-sectional view of a solder joint portion taken along line AA in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electronic component 2, 3 Bus bar 6 Chip component 10, 11 Solder land 15 Solder fillet 16 Void 20 Protrusion part

Claims (3)

A structure in which one or more electronic circuit chip components are mounted on a bus bar, which is two or more bar-shaped metal conductors to be isolated, and the connecting parts of the chip components are connected to the bus bars, and the chip components are joined to the bus bars by soldering. Because
A solder land formed as a recess at a predetermined position on the surface of the bus bar on which the solder fillet is formed, and a protrusion is provided so as to surround the chip component. . The joint structure to the bus bar according to claim 1, wherein a cross-sectional shape of the protrusion is a triangular shape. The said protrusion part is formed simultaneously with the said solder land by press work, The joining structure to the bus-bar of Claim 1 or 2 characterized by the above-mentioned.

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