JP2002237673A - Circuit board device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board device which prevents a short circuit or the like, when solder protrudes on a land and whose productivity and reliability are enhanced, by forming a solder escape hole between the board and the land. SOLUTION: Lands 3 connected to a wiring pattern 2 are insulated on the board 1, and respective electrodes 5A of an electronic component 5 are connected to the lands 3 by the solder 10. Solder escape holes 7, making use of through-holes 6, are formed between the board 1 and the lands 3, and solder attraction lands 8 are installed on the side of a rear surface 1B of the board 1. When the electronic component 5 is mounted, excess solder 10A from among the molten solder 10 is made to escape to the holes 7, and the solder 10A is attracted to the lands 8. Thereby, the solder 10A is prevented from protruding from the lands 3, so as to come into contact with the lands 3 in the circumference, the yield of the circuit board device in its manufacture is increased, and the reliability of the circuit board device can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board device suitably used, for example, for soldering electronic components on a board.

[0002]

2. Description of the Related Art In general, a circuit board device has a plurality of electronic components including, for example, a semiconductor IC, a transistor, a resistor, and a capacitor mounted on a board. A circuit board device according to this type of related art includes a substrate provided with a wiring pattern for forming an electronic circuit, and a land made of a metal material provided on the front surface side of the substrate and connected to the wiring pattern. And electronic components mounted on the front side of the substrate and connected to the lands by solder.

Here, a plurality of lands and a wiring pattern are formed on the front side of the substrate by printing or the like, and these lands are arranged corresponding to electrodes provided on the back side of each electronic component. Have been. Further, in the electronic component, each electrode is fixed to the surface side of the land by soldering, and is connected to a wiring pattern via these lands to form an electronic circuit.

Further, in the prior art, there is also a configuration in which a protective film is formed by applying an insulating material such as a resist on a substrate, and the wiring pattern and the land are covered with the protective film. . In this case, the protective film includes
An opening for exposing each land is provided.

When mounting an electronic component on a board, first, a solder material such as cream solder is applied to the land from each opening of the protective film, and then the electronic component is disposed at a predetermined position on the board. Each of the electrodes is placed on the cream solder. Next, the cream solder is melted by heating the substrate in a high-temperature atmosphere such as a heating furnace, and each electrode is soldered on the land.

[0006]

In the prior art described above, when mounting electronic components, cream solder is applied to each land of the substrate, and after placing each electrode of the electronic components on the solder, The electronic component is soldered by heating and melting the solder.

However, when the cream solder melts and becomes liquid, it becomes crushed between the electrode and the land due to the weight of the electronic component. It may protrude outward from between and come into contact with surrounding lands, electrodes, and the like.

Particularly, in an electronic component such as a semiconductor IC, since a plurality of electrodes are arranged close to each other, even if the solder slightly protrudes from the land, the solder may be adjacent to the land. It has a structure that makes it easy to contact with the electrodes.

For this reason, according to the prior art, when the circuit board device is manufactured, the solder protrudes from the land, so that a connection failure such as a short circuit is liable to occur, which not only deteriorates the manufacturing yield but also increases the reliability. Is reduced.

In the case where a protective film is provided on the substrate, a part of the molten solder is confined in the opening of the protective film between the land and the electrode.
Components such as flux contained in the solder hardly volatilize. As a result, the solder maintains a low viscosity state for a relatively long period of time, and there is a problem that the solder easily oozes out from a minute gap formed between the land and the electrode.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to prevent the solder from leaking out from the land to the periphery when mounting the electronic component, thereby stabilizing the electronic component. It is an object of the present invention to provide a circuit board device which can be soldered efficiently, can increase the yield at the time of manufacturing, and can improve the reliability.

[0012]

According to a first aspect of the present invention, there is provided a substrate provided with a wiring portion for forming an electronic circuit, and the wiring provided on a front surface side of the substrate. The present invention is applied to a circuit board device including a land made of a metal material connected to a portion and an electronic component mounted on the front side of the substrate and connected to the land by solder.

A feature of the structure adopted in the first aspect of the present invention is that a through hole is provided in the substrate so as to penetrate between the front surface side and the back surface side of the substrate, and a through hole is provided between the land surface of the substrate and the substrate. A solder escape hole formed by the through hole is provided between the substrate and the back surface of the substrate, and a metal material is used to surround the solder escape hole on the back surface of the substrate and flows out to the solder escape hole. The present invention is configured to provide a solder attracting land for attracting the solder.

With this configuration, a solder escape hole can be formed between the substrate and the land by using the through hole of the substrate. Then, when the electronic component is mounted, if the solder melts on the land, the surplus of the solder can be accommodated in the solder escape hole and escaped from the land. In addition, the solder drawing land contacts the solder flowing down in the solder escape hole, so that this solder can be attracted and guided to the back side of the board, and excess solder can be removed from the solder escape hole and the solder drawing land. And can be stored over. Also, components such as flux contained in the solder can be volatilized from the solder escape hole to the back surface side of the substrate.

According to the second aspect of the present invention, the solder escape hole has a through-hole structure in which a metal material is adhered to the inner wall.

Thus, when the solder is melted on the land, excess solder can escape into the solder escape hole via the through hole, and at this time, the solder smoothly moves along the metal material forming the through hole. Can flow down.

Further, by forming the land and the inner wall of the through hole using the same metal material as in the third aspect of the present invention, these members and the solder escape hole can be formed together and simultaneously. Can be formed.

Further, according to the invention of claim 4, a closing member for closing the solder escape hole is provided on the back surface side of the substrate.

Thus, the closing member can prevent the extra solder contained in the solder escape hole from protruding from the back surface side of the substrate, and for example, has a configuration in which the thickness dimension of the entire substrate is kept small. Can also.

According to a fifth aspect of the present invention, on the back surface of the substrate, a soldering land is formed using a metal material to surround the solder escape hole and attracts the solder flowing out to the solder escape hole. Is provided.

Thus, the solder attracting land comes into contact with the solder flowing down in the solder escape hole, so that the solder can be attracted and guided to the back side of the substrate, and excess solder can be passed through the solder escape hole. It can be stored over the soldering land.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a circuit board device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 to 6 show a first embodiment of the present invention. In this embodiment, a case where a semiconductor IC, a transistor, or the like is mounted as an electronic component on a substrate is exemplified. State.

In the figure, reference numeral 1 denotes a substrate constituting a main body of the circuit board device. The substrate 1 is formed of, for example, an insulating resin material or the like, and a metal material or the like is printed on the surface 1A side thereof. A plurality of wiring patterns 2, 2, as a wiring portion
... are formed. The front surface 1A and the back surface 1 of the substrate 1
B, as shown in FIG.
… Is drilled.

Are a plurality of lands provided on the front surface 1A side of the substrate 1 so as to be connected to the respective wiring patterns 2. Each of the lands 3 is, for example, a substantially square as shown in FIGS. It is formed of a shaped metal film or the like, and is arranged corresponding to each electrode 5A of the electronic component 5 described later. Land 3
The outer edge is covered with a protective film 9 described later, and a central portion thereof is exposed at a position of an opening 9A provided in the protective film 9. Also, between the substrate 1 and the lands 3, there are provided solder escape holes 7, 7,...

Reference numeral 4 denotes an electronic circuit mounted on the substrate 1. The electronic circuit 4 includes, as shown in FIG.
It is configured to include other electronic components including passive elements such as resistors and capacitors, and these electronic components 5 and the like are connected to each other by the wiring pattern 2.

Reference numeral 5 denotes a substantially rectangular electronic component constituting a part of the electronic circuit 4. The electronic component 5 is, for example, a ROM or RA.
M, a semiconductor IC such as a microprocessor or a transistor, and a plurality of electrodes 5A, 5
A,... Are formed. In the electronic component 5, each electrode 5 </ b> A is connected to the surface of the land 3 by a solder 10 described later, and is mounted on the substrate 1.

Are a plurality of through-holes formed through the substrate 1 at positions corresponding to the lands 3. Each through-hole 6 has an opening in the front surface 1A and the back surface 1B of the substrate 1. And constitutes a part of the solder escape hole 7.

Are a plurality of solder escape holes provided between the substrate 1 and each land 3. Each of the solder escape holes 7
A land side hole 7A formed through the land 3 in the opening 9A of the protective film 9, and communicates with the land side hole 7A;
It is formed by a substrate side hole 7B formed by the through hole 6 of the substrate 1. Further, the solder escape holes 7 are opened to the front surface side of the lands 3 and the back surface 1B side of the substrate 1 via the through holes 6.

When the electronic component 5 is mounted, as shown in FIG. 6 to be described later, of the solder 10 melted between the land 3 and the electrode 5A of the electronic component 5, the excess solder 10A
Flows out of the land 3 into the solder escape hole 7. Thus, the solder escape hole 7 accommodates the excess solder 10A and escapes from the land 3 to prevent the solder 10A from protruding outside the land 3.

.. Are a plurality of solder drawing lands provided on the back surface 1B side of the substrate 1 corresponding to the respective solder escape holes 7, and the respective solder drawing lands 8 are made of, for example, a metal material. By printing on the back surface 1B of the substrate 1, it is formed as an annular metal film surrounding the opening of the solder escape hole 7.

When the solder 10 on the land 3 is melted, excess solder 10A flows down through the solder escape hole 7 and comes into contact with the solder drawing land 8.
Since A rises in a convex curved shape on the solder drawing land 8 due to surface tension, the solder 10A in the solder escape hole 7 is attracted to the solder drawing land 8 and easily flows toward the back surface 1B side of the substrate 1. Become. Thus, the solder drawing land 8 guides the excess solder 10A from the solder escape hole 7 to the back surface 1B side of the substrate 1 and stores the solder 10A on the solder drawing land 8.

Reference numeral 9 denotes a protective film provided on the front surface 1A side of the substrate 1. The protective film 9 is formed by applying an insulating material such as a resist on the substrate 1, and includes a wiring pattern 2 and a land. 3 and the outer edge side. As shown in FIG. 4, the protective film 9 is provided with a plurality of openings 9A for exposing the center of each land 3.

Are electrodes 5A of the electronic component 5.
The solder 10 is provided between the land 3 and the land 3, for example.
It is formed by coating on top. The excess solder 10A when the electronic component 5 is mounted is held over the solder escape hole 7 and the solder drawing land 8.

The circuit board device according to the present embodiment has the above-described configuration. Next, a mounting operation of the electronic component 5 will be described.

First, when the electronic component 5 is mounted, as shown in FIG. 5, the wiring pattern 2, land 3, solder escape hole 7 (through hole 6), solder drawing land 8, protective film 9
Are formed in advance. Then, a solder material 10 ′, such as cream solder, is applied onto the lands 3 through the openings 9 A of the protective film 9.

Next, the electronic component 5 is disposed at a predetermined position on the substrate 1, and each electrode 5A is connected to the solder material 1 as shown in FIG.
After each of them is placed on 0 ', the substrate 1 is heated in a high-temperature atmosphere such as a heating furnace to melt the solder material 10'. Thus, each solder material 10 ′ becomes the solder 10 in the opening 9 A of the protective film 9, and connects each land 3 on the substrate 1 and the electrode 5 A of the electronic component 5. At this time, the solder 10
Is volatilized from the solder escape hole 7 to the back surface 1B side of the substrate 1 as well.

The surplus solder 1 of the solder 10
0A flows out of the land side hole 7A of the solder escape hole 7 into the board side hole 7B (through hole 6) due to its own weight, the weight of the electronic component 5, and the like.

At this time, when the solder 10A flows down through the solder escape hole 7 and comes into contact with the solder attracting land 8, it is attracted to the solder attracting land 8 and easily flows to the back surface 1B side of the substrate 1. Therefore, the excess solder 10A can smoothly escape into the solder escape hole 7, and the solder 10A can be accumulated between the solder escape hole 7 and the solder drawing land 8.

Thus, according to the present embodiment, the substrate 1
A solder escape hole 7 is provided between the substrate 1 and the land 3 by a through hole 6 or the like of the substrate 1, and a solder attracting land 8 is provided on the back surface 1 </ b> B side of the substrate 1. When the solder melts, the excess solder 10A can be reliably released from the land 3 into the solder release hole 7.

At this time, the solder attracting land 8 is attached to the back surface 1B of the substrate 1 with respect to the solder 10A flowing down in the solder escape hole 7.
Side, and the solder 10A can be attracted and guided to the back surface 1B side. Thereby, the solder 10A can be smoothly discharged from the land 3 into the solder escape hole 7. For example, even when the surplus amount of the solder 10A is relatively large, the solder escape hole 7 and the solder drawing land 8 can be used. Thus, a sufficient amount of solder 10A can be stored.

Therefore, when the electronic component 5 is mounted, it is ensured that the excess solder 10A does not protrude from between the land 3 and the electrode 5A and come into contact with the surrounding wiring pattern 2, land 3, electrode 5A and the like. It is possible to stably solder the respective electrodes 5A of the electronic component 5 to the predetermined lands 3, respectively.
Improves manufacturing yield by preventing connection failures such as short circuits,
Reliability can be improved.

Further, since the solder escape hole 7 is formed by the through hole 6 or the like, when the electronic component 5 is mounted, the molten solder 1
0 is located between the land 3 and the electrode 5A and is confined in the opening 9A of the protective film 9,
Components such as flux contained in the substrate 0 can also be volatilized from the through hole 6 of the substrate 1 to the back surface 1B side, and the volatility can be increased to prevent the solder 10 from leaching more reliably.

Next, FIG. 7 shows a second embodiment of the present invention, which is characterized in that a solder escape hole is provided between a substrate and a land via a through hole. It is in. Note that, in the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Reference numeral 11 denotes a substrate formed of, for example, an insulating resin material. The substrate 11 has a wiring pattern 2, lands 3, and electronic components on its front surface 11A side in substantially the same manner as in the first embodiment. 5, a protective film 9 and the like are provided. However, the substrate 11 is provided with a through hole 13 and the like in a through hole 12 described below, which is located between the front surface 11A and the back surface 11B.

Are a plurality of through-holes (only one is shown) formed through the substrate 11 at positions corresponding to the lands 3, and each of the through-holes 12 is a surface 11A of the substrate 11.
And the back surface 11B.

Are a plurality of through holes in which a metal material is provided on the inner wall of each through hole 12. Each through hole 13 is formed of a cylindrical thin film that covers the inner wall of each through hole 12. The lands 3 are formed together (integrally) using the same metal material as the metal material constituting the lands 3.

Are a plurality of solder escape holes provided between the substrate 11 and each land 3. Each of the solder escape holes 14 penetrates the land 3 within the opening 9A of the protective film 9. The land side hole 14A formed by
A and a substrate side hole 14B formed inside the through hole 13 and communicating with A. The solder escape holes 14 are opened through the through holes 13 on the front surface side of the lands 3 and on the back surface 11B side of the substrate 11.

When the electronic component 5 is mounted, the excess solder 10 out of the solder 10 melted between the land 3 and the electrode 5A of the electronic component 5 is substantially similar to the first embodiment.
A flows out from the land side hole 14A of the solder escape hole 14 into the board side hole 14B. At this time, since the inner wall of the solder escape hole 14 is formed by the through hole 13 made of a metal material, the solder 10A smoothly flows downward along the through hole 13 and comes into contact with, for example, an insulating film 15 described later. It will flow down to the position. Thus, the solder escape hole 14 accommodates the excess solder 10A and escapes from the land 3 to prevent the solder 10A from protruding outside the land 3.

Reference numeral 15 denotes an insulating film as a closing member provided on the back surface 11B side of the substrate 11. The insulating film 15 is formed of an insulating material such as a resist, for example.
4 (through hole 13) is closed on the back surface 11B side of the substrate 11. The insulating film 15 prevents the solder 10A flowing down in the solder escape hole 14 from protruding from the back surface 11B of the substrate 11.

Thus, also in the present embodiment configured as described above, it is possible to obtain substantially the same operation and effect as in the first embodiment. And especially in this embodiment,
Since the solder escape hole 14 is provided via the through hole 13, when the solder 10 is melted on the land 3, the excess solder 10 </ b> A flows smoothly along the through hole 13 in the solder escape hole 14. , Solder 10
A can efficiently escape into the solder escape hole 14.

Further, since the solder escape hole 14 is closed on the back surface 11B side of the substrate 11 by the insulating film 15, it is possible to prevent the solder 10A flowing into the solder escape hole 14 from projecting from the back surface 11B side of the substrate 11. Can be prevented. As a result, each through hole 13 is formed on the back surface 11B side of the substrate 11.
Can be prevented from being erroneously short-circuited, and the thickness of the entire substrate 11 including the solder 10A can be reduced.

Further, since the through holes 13 are integrally formed using the same metal material as the lands 3, the solder escape holes 14 can be efficiently formed together with the lands 3 and the through holes 13 at the same time. Can be.

Next, FIG. 8 shows a third embodiment of the present invention, which is characterized in that a solder escape hole via a through hole and a solder drawing land are provided together. It is in. In the present embodiment, the first
The same reference numerals are given to the same components as those of the embodiment, and the description thereof will be omitted.

Reference numeral 21 denotes a substrate formed of, for example, an insulating resin material. The substrate 21 has a wiring pattern 2 on its front surface 21A side in substantially the same manner as in the second embodiment.
Land 3, electronic component 5, protective film 9, etc. are provided, and surface 2
A through hole 22, a through hole 23, and the like are formed between 1A and the back surface 21B. A land side hole 24A and a substrate side hole 24B are provided between the substrate 21 and the land 3.
Is formed through the through hole 23.

Are a plurality of solder drawing lands (only one is shown) provided on the back surface 21B side of the substrate 21 corresponding to each solder escape hole 24.
Is substantially the same as that of the first embodiment, for example, the substrate 2
The first back surface 21B is formed of an annular metal film surrounding the opening of the solder escape hole 24, and is integrally formed of the same metal material as the land 3 and the through hole 23.

When the electronic component 5 is mounted, the excess solder 10A of the solder 10 melted between the land 3 and the electrode 5A of the electronic component 5 is transferred from the land side hole 24A of the solder escape hole 24 to the substrate side. The solder 1 flows out into the hole 24B,
0A flows down smoothly along the through hole 23. Further, the solder 10 </ b> A comes into contact with the solder drawing land 25 to be drawn from the solder escape hole 24 toward the solder drawing land 25, and the solder escape hole 24 and the solder drawing land 25 are formed.
It is configured to accumulate over this.

Thus, in the present embodiment configured as described above, substantially the same operation and effect as those of the first and second embodiments can be obtained. In particular, in the present embodiment, since the solder attracting land 25 surrounding each solder escape hole 24 is provided on the back surface 21B side of the substrate 21, the land 3 is formed by the solder escape hole 24 and the solder attracting land 25. The upper excess solder 10A can be efficiently escaped, and a sufficient amount of solder 10A can be stored in these portions.

In the second embodiment, the solder escape hole 14 is closed by the insulating film 15 on the back surface 11B side of the substrate 11. However, the present invention is not limited to this. May be configured to use another closing member,
Further, a configuration in which the closing member is omitted may be adopted.

In each of the embodiments, the electronic component 5 composed of a semiconductor IC, a transistor and the like is mounted on the substrate 1, 11, 21 or
Although the configuration is described above, the present invention is not limited to this, and may be configured to be applied to various electronic components including, for example, a resistor and a capacitor.

[0061]

As described above in detail, according to the first aspect of the present invention, a solder escape hole is formed between the substrate and the land by a through hole of the substrate, and the solder drawing land is formed on the back side of the substrate. When the solder melts on the lands, the excess solder can be reliably released into the solder escape holes.At this time, the solder is attracted by the solder attraction lands and into each solder escape hole. And a sufficient amount of solder can be stored over these solder escape holes and solder drawing lands. Therefore, when mounting electronic components, excess solder can be prevented from protruding from the lands and coming into contact with surrounding conductors and the like, and the electronic components can be stably soldered to the lands and connection defects such as short circuits can be prevented As a result, the yield during manufacturing can be increased, and the reliability can be improved. Further, the flux and the like in the solder can be volatilized from the solder escape hole to the back surface of the substrate, and the volatility can be increased to prevent the solder from leaching more reliably.

According to the second aspect of the present invention, since the solder escape hole has a through-hole structure, when the solder is melted on the land, excess solder is removed along the metal material forming the through-hole. It can smoothly escape into the escape hole. Therefore, at the time of mounting the electronic component, it is possible to reliably prevent excess solder from protruding from the land and coming into contact with the surrounding conductors and the like, and it is possible to increase the production yield and improve the reliability.

According to the third aspect of the present invention, since the land and the inner wall of the through hole are formed by using the same metal material, the solder escape hole is formed together with the land and the through hole and simultaneously. Can be formed efficiently.

Further, according to the fourth aspect of the present invention, since the closing member for closing the solder escape hole is provided on the back surface side of the substrate, the closing member is provided with an extra part accommodated in the solder escape hole. It can prevent solder from protruding from the back side of the board,
It is possible to prevent each through-hole from being erroneously short-circuited on the back surface side of the substrate, and to make the thickness of the entire substrate small, for example.

According to the fifth aspect of the present invention, since the solder drawing land surrounding the solder escape hole is provided on the back side of the substrate, the solder pull land flows down in the solder escape hole. By contacting the solder, the excess solder can be attracted and smoothly guided into the solder escape hole, and the solder can be stably stored over the solder escape hole and the solder attachment land.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a circuit board device according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a substrate, an electronic component, and the like as viewed from a direction indicated by arrows II-II in FIG.

FIG. 3 is an enlarged sectional view of a main part in FIG. 2 showing a connection portion between a land and an electronic component.

FIG. 4 shows a connection portion between a land and an electronic component in an arrow in FIG.
FIG. 4 is a cross-sectional view as viewed from the IV-IV direction.

FIG. 5 is an enlarged sectional view showing a state before electronic components are mounted on a substrate.

FIG. 6 is a diagram showing a state in which excess solder flows out of the land into the solder escape hole when the electronic component is mounted on the land.
It is an important section enlarged sectional view in the inside.

FIG. 7 is an enlarged cross-sectional view of a main part at a position similar to FIG. 6 showing a part of a circuit board device according to a second embodiment of the present invention.

FIG. 8 is an enlarged sectional view of a main part at a position similar to FIG. 6 showing a part of a circuit board device according to a third embodiment of the present invention.

[Explanation of symbols]

 1, 11, 21 Substrate 1A, 11A, 21A Front surface 1B, 11B, 21B Back surface 2 Wiring pattern (wiring portion) 3 Land 4 Electronic circuit 5 Electronic component 5A Electrode 6, 12, 22 Through hole 7, 14, 24 Solder escape hole 7A, 14A, 24A Land side hole 7B, 14B, 24B Board side hole 8, 25 Solder land 9 Protective film 9A Opening 10, 10A Solder 13, 23 Through hole 15 Insulating film (blocking member)

Claims (5)

[Claims] 1. A substrate on which a wiring portion for forming an electronic circuit is provided, a land made of a metal material provided on the front surface side of the substrate and connected to the wiring portion, and mounted on the front surface side of the substrate A circuit board device comprising an electronic component connected to the land by soldering, wherein the substrate has a through-hole penetrating between a front side and a back side of the substrate; A solder escape hole formed by the through hole is provided between the solder escape hole and the back surface side of the substrate. The solder escape hole is formed on the back surface side of the substrate by surrounding the solder escape hole using a metal material. A circuit board device characterized in that a solder attracting land for attracting the solder flowing to the circuit board is provided. 2. The circuit board device according to claim 1, wherein the solder escape hole has a through-hole structure in which a metal material is attached to an inner wall. 3. The circuit board device according to claim 2, wherein the land and the inner wall of the through hole are formed using the same metal material. 4. The circuit board device according to claim 2, wherein a closing member for closing the solder escape hole is provided on a back surface side of the board. 5. A soldering land which is formed on a rear surface side of the substrate using a metal material so as to surround the solder escape hole and attracts solder flowing out to the solder escape hole. Or the circuit board device according to 3.