JP2003142795A - Mounting structure of electric component to board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely solder between a through hole and a lead while surely preventing defective soldering between them, even if the temperature difference between the melting point of solder and the temperature of a molten solder is small, or even if the thermal capacity of an electric component and board is large. SOLUTION: In a mounting structure 10, an electric component 8 is mounted to a board 9 by inserting a lead 14 provided on the electric component 8 into a through hole 11 provided to the board 9 from a front surface 9a side of the board 9 and then soldering between the through hole 11 and the lead 14 from a rear surface 9b side of the board 9. The lead 14 comprises a section in which a tip side gradually becomes smaller relative to a base end in cross section within the through hole 11, while the interval from the through hole 11 is larger on the rear surface side of the board 9 than the front surface side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for mounting an electric component on a substrate, in which a lead portion is soldered to the substrate in a through hole and mounted on the substrate.

[0002]

2. Description of the Related Art For electrical parts such as relays and connectors,
Some are mounted on a board having a predetermined printed wiring pattern. As a mounting structure of this electric component on a substrate, there is, for example, a structure shown in FIG.

As shown in FIG. 4, in the mounting structure 3 for mounting the electric component 1 on the substrate 2, the through hole 4 provided in the substrate 2 is used.
The lead portion 5 provided in the electric component 1 is inserted thereinto,
The space between the through hole 4 and the lead portion 5 is soldered.

A printed wiring pattern (not shown) is provided on the front surface 2a and the back surface 2b of the substrate 2. This substrate 2 is provided with through holes 4 having a substantially same diameter and penetrating from a front surface 2a to a back surface 2b at a predetermined position. The through hole 4 of the substrate 2 is provided with a hole electrode 8 which is continuous with a predetermined end portion of the printed wiring pattern on the inner peripheral surface.

On the other hand, in the electric component 1, a plurality of lead portions 5 which are electrodes are provided so as to project from the lower surface of the component body 6 which constitutes the main part. The lead portion 5 of the electric component 1 is formed in a rectangular plate shape and has substantially the same cross-sectional shape from the base end to the tip. Then, in the electric component 1, the lead portion 5 is inserted into the through hole 4 of the substrate 2 from the surface 2a side, and the lead portion 5 is soldered between the lead portion 5 and the through hole 4 of the substrate 2 to be attached to the surface 2a of the substrate 2. It is implemented. Therefore,
In the electric component 1, the lead portion 5 is electrically connected to the printed wiring pattern of the substrate 2 via the solder 7 and the hole electrode 5 of the through hole 4.

In such a mounting structure 3, when the electric component 1 is mounted on the substrate 2, the lead portion 5 of the electric component 1 is mounted on the substrate 2.
Through the through hole 4 of the substrate 2 from the surface 2a side,
The electric component 1 is held at a predetermined position on the substrate 2. Then, after the substrate 2 is preheated by a flow soldering device (not shown), the molten solder 7 is jetted from the back surface 2b side of the substrate 2 to form a space between the lead portion 5 of the electric component 1 in the through hole 4. Fill with solder 7.

At this time, the melted solder 7 passes between the lead portion 5 of the electric component 1 in the through hole 4 and the surface 2 of the substrate 2.
In the mounting structure 3, the lead portion 5 of the electric component 1 and the through hole 4 are soldered to mount the electric component 1 on the board 2.

[0008]

However, in the above-described conventional mounting structure 3 for mounting the electric component 1 on the substrate 2, when the electric component 1 is mounted on the substrate 2, for example, the melting point of the solder 7 and the flow soldering device When the difference from the temperature of the melted solder 7 is small or when the heat capacity of the electric component 1 and the board 2 is large,
The amount of heat required to maintain the molten state of the solder 7 flowing in the through hole 4 toward the surface 2a of the substrate 2 is likely to be insufficient. When the amount of heat of the solder 7 is insufficient as described above, in the mounting structure 3, the inside of the through hole 4, particularly the surface 2a of the substrate 2 is formed.
Does not flow sufficiently to the side, and even if it flows, the solder 7 is solidified before being soldered, so that soldering failure occurs between the through hole 4 of the substrate 2 and the lead portion 5 of the electric component 1. Sometimes.

Therefore, the present invention has been made in consideration of the above conventional problems, and an object of the present invention is to provide a mounting structure for mounting an electric component on a substrate capable of reliably preventing a soldering failure.

[0010]

In order to achieve the above object, the invention according to claim 1 inserts a lead portion provided in an electric component from a front surface side of the board into a through hole provided in the board. A mounting structure for mounting an electrical component on the substrate, wherein a space between the through hole and the lead portion is soldered from the back surface side of the substrate, wherein the lead portion is located in the through hole with respect to a base end side. It is characterized in that the front end side has a portion whose cross-sectional shape is gradually reduced, and the distance between the front end side and the through hole is increased on the back surface side with respect to the front surface side.

In the invention according to claim 1 having such a configuration, since the distance between the through hole and the lead portion is increased on the back surface side with respect to the front surface side of the substrate, the distance between the through hole and the lead portion is increased. The pressure rises when the solder filled in the substrate flows from the back side to the front side of the substrate. Therefore, the solder easily flows from the back surface side to the front surface side of the substrate due to the pressure difference.

According to a second aspect of the present invention, there is provided a mounting structure for mounting the electric component on the substrate according to the first aspect, wherein a portion of the lead portion whose cross-sectional shape is gradually reduced is at least a side surface in the through hole. A part is inclined from the base end side toward the tip end side.

According to the invention of claim 2 configured as described above, in addition to the function of the invention of claim 1, at least a part of the side surface of the lead portion is inclined from the base end to the tip, so that it is melted. When the space between the through hole and the lead portion is filled with the solder, the solder flows while being guided to the front surface side by the inclination of a part of the side surface thereof. Therefore, it is possible to facilitate the flow between the through hole and the lead portion from the back surface side to the front surface side of the substrate.

According to a third aspect of the present invention, there is provided a structure for mounting the electric component on the substrate according to the second aspect, wherein the side surface of the lead portion is inclined in the entire area of the through hole. To do.

According to the third aspect of the invention thus constructed, in addition to the operation of the second aspect of the invention, the side surface of the lead portion is inclined so as to be close to the tip from the base end in the entire area of the through hole. Therefore, it is possible to facilitate the flow between the through hole and the lead portion from the back surface side to the front surface side of the substrate.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, details of a mounting structure of an electric component according to the present invention on a substrate will be described based on an embodiment shown in the drawings. FIG. 1 is a schematic configuration sectional view showing an embodiment of a mounting structure of an electric component on a substrate according to the present invention.

In the mounting structure 10 for mounting the electric component 8 on the substrate 9 according to the present embodiment, as shown in FIG. 1, the lead portion 14 provided on the electric component 8 is provided in the through hole 11 provided on the substrate 9. 9 is inserted from the surface 9a side, and the through hole 11 and the lead portion 14 are soldered to each other to form the electrical component 8
Are mounted on the surface 9 a of the substrate 9. This mounting structure 1
0 indicates that the lead portion 14 of the electric component 8 has the through hole 11
In the inside, there is a portion where the cross-sectional shape is gradually reduced on the front end side with respect to the base end side, and between the through hole 11 and the front surface 9a side of the substrate 9 is increased on the back surface 9b side. is there.

A printed wiring pattern (not shown) is provided on the front surface 9a and the back surface 9b of the substrate 9. This substrate 9 is provided with through-holes 11 at a predetermined position, which penetrate from the front surface 9a to the back surface 9b with substantially the same diameter. The through hole 11 of the substrate 9 is formed of copper or the like on the inner peripheral surface thereof, and the hole electrode 12 continuous to a predetermined end portion of the printed wiring pattern is provided.

On the other hand, the electric component 8 is composed of a connector, a relay and the like, and a plurality of lead portions 14 which are electrodes are projected from the lower surface of the component body 13 which constitutes the main part. The lead portion 14 is formed in a substantially inverted triangular plate shape made of a conductive metal, and is inclined so that the side surfaces 14a, 14a arranged on both sides in the width direction of the outer peripheral surface are close to each other from the base end to the tip. The cross-sectional shape is gradually decreasing. That is, the lead portion 14 is a portion whose cross-sectional shape is gradually reduced on the distal end side with respect to the proximal end side as a whole.

The lead portion 14 is inserted into the through hole 11 from the front surface 9a side of the substrate 9, and the outer peripheral surface is gradually formed in a cross section from the base end to the tip between the hole electrode 12 in the entire area of the through hole 11. A gap that gradually increases from the front surface 9a side to the back surface 9b side of the substrate 9 in accordance with the reduction in size is formed. Then, the lead portion 14 is
The hole electrode 12 is inserted through the solder 15 filled in the gap.
Is soldered.

In the mounting structure 10 thus constructed,
When the electric component 8 is mounted on the substrate 9, the lead portion 14 of the electric component 8 is inserted into the through hole 11 of the substrate 9 so that the surface 9 of the substrate 9
The electrical component 8 is held at a predetermined position on the surface 9a of the substrate 9 by inserting from the side a. Then, after the substrate 9 is preheated by a flow soldering device (not shown), the melted solder 15 is jetted from the back surface 9b side of the substrate 9. Then,
The mounting structure 10 includes a hole electrode 12 in a through hole 11.
And the outer peripheral surface of the lead portion 14 of the electric component 8 is filled with the solder 15 pushed up from the back surface 9b side by a predetermined pressure.

At this time, in the mounting structure 10, the clearance is gradually increased from the front surface 9a side to the back surface 9b side of the substrate 9, that is, the clearance is gradually decreased from the back surface 9b side to the front surface 9a side. The pressure of the solder 15 gradually rises as the solder 15 flows inside. Therefore, the solder 15 is applied to the back surface 9b of the substrate 9 by the increased pressure.
Is pushed up to the side to facilitate the flow to the surface 9a side,
The flow velocity also increases, and it becomes easier for the substrate 9 to flow to the surface 9a side.

Further, in the mounting structure 10, since the cross-sectional shape of the lead portion 14 on the tip end side is gradually reduced with respect to the base end side, the area where the solder 15 contacts the lead portion 14 on the tip end side is reduced. ing. Therefore, the mounting structure 10
Then, the heat radiation of the solder 15 on the tip side of the lead portion 14 can be reduced, and the temperature drop of the solder 15 can be suppressed accordingly, so that the solder 15 can be transferred from the rear surface 9b side of the substrate 9 to the front surface 9a.
It can be made easier to flow to the side.

When the solder 15 is filled in the gap to the surface 9a side of the substrate 9, the hole electrode 12 and the outer peripheral surface of the lead portion 14 are soldered over the entire inside of the through hole 11. .

As described above, in the mounting structure 10, the lead portion 14 of the electric component 8 and the hole electrode 12 provided on the inner peripheral surface of the through hole 11 are soldered to each other so that the electric component 8 is on the surface of the substrate 9. 9a.

In the mounting structure 10 of the present embodiment, the gap between the hole electrode 12 and the outer peripheral surface of the lead portion 14 is gradually reduced from the back surface 9b side to the front surface 9a side of the substrate 9, so that the electric component 8 is formed. As the molten solder 15 filled in the gap flows from the back surface 9b side to the front surface 9a side of the board 9, the pressure of the solder 15 gradually increases.

Therefore, in the mounting structure 10, as compared with the case where the cross section of the lead portion of the electric component is uniform from the base end side to the tip end side, the solder 15 has the back surface 9b side to the front surface 9 side of the substrate 9.
Even if the heat capacity of the substrate 9 is large due to a large printed wiring pattern of the substrate 9 or a large electrical component 8 itself, for example, the solder 15 remains melted in the molten state. It is possible to reliably fill the surface 9a side of the substrate 9. Therefore, the mounting structure 1
At 0, the hole electrode 12 and the outer peripheral surface of the lead portion 14 can be reliably soldered over the entire area of the through hole 11, and the soldering failure between the lead portion 14 and the through hole 11 can be reliably prevented and the electrical conductivity can be improved. The reliability of the connection between the component 8 and the board 9 can be improved.

Further, for example, Sn / Pb as the solder 15 is used.
Lead-free solder (Sn with higher strength after soldering than eutectic)
When Ag, Cu) is used for the base, Sn / Pb
Many have a higher melting point than eutectic solder. And
There is an upper limit to the temperature of the melted solder 15 due to the heat resistance of the substrate 9 and the electric component 8, and the melting point of the solder 15 and the melted solder 15
However, according to the present invention, the melted solder 15 is melted at the base portion of the lead section of the electric component. As compared with the case where the surface is uniform from the side to the tip side, the flow can be facilitated from the back surface 9b side to the front surface 9a side of the substrate 9, and the front surface 9a side of the substrate 9 can be reliably filled.

Therefore, in the mounting structure 10, the solder 15
Even when there is a small difference between the melting point of the solder and the heating temperature of the solder 15, the hole electrode 12 and the outer peripheral surface of the lead portion 14 can be reliably soldered over the entire area in the through hole 11, that is, the lead portion. It is possible to reliably prevent the soldering failure between the through hole 14 and the through hole 11 and improve the reliability of the connection between the electric component 8 and the substrate 9.

Further, in the mounting structure 10, the hole electrode 12
Since the clearance between the outer peripheral surface of the lead portion 14 and the outer peripheral surface of the lead portion 14 gradually decreases from the back surface 9b side of the substrate 9 toward the front surface 9a side,
The solder filled in the above-mentioned gap is transferred from the rear surface 9b side to the front surface 9a.
The flow velocity increases as it flows to the side. Therefore, in the mounting structure 10, the solder 15 can be made to flow more easily from the back surface 9b side to the front surface 9a side of the substrate 9, and the hole electrode 12 and the outer peripheral surface of the lead portion 14 can be distributed over the entire area of the through hole 11. It is possible to solder more reliably.

Further, in the mounting structure 10, since the lead portion 14 of the electric component 8 has a cross-sectional shape that gradually decreases from the base end side to the tip end side, the lead portion cross section of the electric component extends from the base end side to the tip end side. The area where the solder 15 contacts the lead portion 14 on the tip side is smaller than that in the case where the solder 15 is uniform. Therefore, in the mounting structure 10, the lead portion 1
It is possible to reduce the heat radiation of the solder 15 at the tip end side of 4,
The solder 15 can be made to flow more easily from the back surface 9b side of the substrate 9 to the front surface 9a side.

Therefore, in the mounting structure 10, the hole electrode 12 and the outer peripheral surface of the lead portion 14 can be soldered more reliably over the entire area of the through hole 11.

Further, in the mounting structure 10, the lead portion 14 of the electric component 8 is inclined so that the side surfaces 14a, 14a thereof are close to each other from the base end to the tip, and the cross-sectional shape is gradually reduced. When the gap 15 is filled with the above-mentioned gap, the surface 9a is formed by the inclination of the side surfaces 14a, 14a.
It flows while being guided to the side. Therefore, the mounting structure 10
Then, the solder 15 is placed on the back surface 9b of the substrate 9 in the gap.
Side to the surface 9a side can be made to flow easily, and more reliably between the hole electrode 12 and the outer peripheral surface of the lead portion 14,
It is possible to solder more reliably.

Further, in the mounting structure 10, the lead portion 14 of the electric component 8 has the side surfaces 14a, 14a inclined from the base end to the tip, so that the solder 15 and the lead portion 11 are formed.
The area of contact with the lead portion 1 can be increased, and the lead portion 1
It is possible to delay the degree of progress of cracks that occur along the line 4.

Since the size of the above-mentioned gap of the mounting structure 10 is large on the back surface 9b side of the substrate 9 filled with the melted solder 15, the melted solder 15 easily enters.

The substrate 9 of the electric component 8 according to the present invention has been described above.
Although one embodiment of the mounting structure 10 has been described above, the present invention is not limited to this, and various design changes associated with the constituent elements are possible. For example, in the above-described embodiment, the melted solder 15 is used as the soldering means.
Although the flow soldering device that jets the solder from the back surface 9b side of the substrate 9 is used, the solder 15 is locally jetted only to the portion of the substrate 9 where the electric component 8 is provided by using the local flow soldering device. Alternatively, the substrate 9 may be simply immersed in the melted solder 15, or the thread-like solder may be manually or automatically melted by a soldering hand.

Further, although the lead portion 14 of the electric component 8 is formed in a plate shape, it may be formed in a column shape such as a column.

Further, the lead portion 14 of the electric component 8 is a portion in which the side faces 14a, 14a are inclined so that the side faces 14a, 14a are close to each other from the base end to the tip, and the overall cross-sectional shape is gradually reduced. Even if the cross-sectional shape is gradually reduced, such as a two-stage configuration in which a rectangular plate-shaped portion wide in the width direction on the base end side and a rectangular plate-shaped portion narrow in the width direction on the tip end side are integrally molded. Good.

Further, the lead portion of the electric component is, for example,
As shown in the modified examples of FIGS. 2 and 3, a part of the side surface in the through hole 11 may be inclined from the base end side toward the tip end side so that the cross-sectional shape is gradually reduced.

In the modification shown in FIG. 2, the lead portion 17 is inclined so that the side surfaces 17a, 17a are close to each other toward the tip from the base end to the middle portion in the longitudinal direction, and the lead portion 17 is gradually reduced to a plate-like shape. It is formed in a rectangular plate shape having side faces 17b, 17b continuous with the side faces 17a, 17a from the middle portion to the tip. That is, in this modification, the intermediate portion in the longitudinal direction from the base end is a portion whose cross-sectional shape is gradually reduced.

Further, in another modification shown in FIG. 3, the lead portion 18 is formed in a rectangular plate shape from the middle portion to the base end in the longitudinal direction, and the side surfaces 18a, 18a face the tip from the middle portion to the tip. It is formed in a plate shape that is inclined so as to come close to each other and gradually decreases in cross-sectional shape. That is,
In this modification, the cross-sectional shape is gradually reduced from the middle portion in the longitudinal direction to the tip.

Even in the modified examples shown in FIGS. 2 and 3, substantially the same actions and effects as the mounting structure 10 of the above-described embodiment can be obtained.

[0043]

As described above, according to the first aspect of the present invention, since the distance between the through hole and the lead portion is increased on the back surface side with respect to the front surface side of the substrate, the through hole and the lead portion are formed. The pressure rises when the solder filled between the parts flows from the back surface side to the front surface side.

Therefore, it is possible to facilitate the flow of the solder between the through hole and the lead portion from the back surface side to the front surface side of the substrate, and when the difference between the melting point of the solder and the temperature of the molten solder is small, the electric component, Even if the amount of heat required to maintain the molten state of the solder is insufficient, such as when the heat capacity of the board is large, solder between the through hole and the lead section is surely soldered over the entire area of the through hole. Therefore, defective soldering between the lead portion and the through hole can be reliably prevented, and the reliability of the connection between the electric component and the substrate can be improved.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, since at least a part of the side surface of the lead portion is inclined from the base end to the tip, the molten solder is When it is filled between the through hole and the lead portion, it flows while being guided to the surface side by the inclination of a part of the side surface thereof. Therefore, it is possible to facilitate the flow between the through hole and the lead portion from the back surface side to the front surface side of the substrate, and it is possible to more reliably solder the through hole and the lead portion.

According to the invention of claim 3, in addition to the effect of the invention of claim 2, since the side surface of the lead portion is inclined in the entire area of the through hole, the space between the through hole and the lead portion is increased. Can be made to flow more easily from the back surface side to the front surface side of the substrate, so that the solder can be more reliably soldered between the through hole and the lead portion.

[Brief description of drawings]

FIG. 1 is a schematic configuration sectional view showing a first embodiment of a mounting structure of an electric component on a substrate according to the present invention.

FIG. 2 is a schematic configuration cross-sectional view showing a modified example of the mounting structure shown in FIG.

FIG. 3 is a schematic configuration cross-sectional view showing another modified example of the mounting structure shown in FIG.

FIG. 4 is a schematic configuration sectional view showing a mounting structure of a conventional electric component on a substrate.

[Explanation of symbols]

8 electrical components 9 substrates 9a surface 9b back side 10 Mounting structure 11 through holes 14,17,19 Lead part 14a, 18a, 18b, 19a, 19b Side surface 15 Solder

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hitoshi Ikeya             Yazaki, 206, Nunobikihara, Haibara-cho, Haibara-gun, Shizuoka Prefecture             Parts Co., Ltd. F term (reference) 5E336 AA01 BB02 BC04 CC02 CC03                       CC51 CC55 EE01 GG05

Claims (3)

[Claims] 1. A lead portion provided on an electric component is inserted into a through hole provided in a substrate from the front surface side of the substrate, and a solder is provided between the through hole and the lead portion from the back surface side of the substrate. A mounting structure for mounting an electric component to be mounted on a substrate, wherein the lead portion has a portion in which a cross-sectional shape of a tip end side is gradually reduced with respect to a base end side in the through hole, A mounting structure for mounting an electric component on a substrate, wherein a space between the front surface side and the rear surface side of the substrate is increased. 2. The mounting structure for mounting an electrical component on a substrate according to claim 1, wherein at least a part of a side face of the through hole is formed in the base end in a portion where the cross-sectional shape of the lead portion is gradually reduced. A mounting structure for mounting an electric component on a substrate, wherein the mounting structure is inclined from the side toward the tip side. 3. The mounting structure for an electric component according to claim 2, wherein the side surface of the lead portion is inclined in the entire area of the through hole. Implementation structure of.