JP2002374058A - Mounting structure for electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure whose solderability is satisfactory, even when a wiring pattern on a printed-wiring board is wide and even when the mounting area of an electronic component and the electronic component itself are large. SOLUTION: In the mounting structure for the electronic component 13, a connecting pad part 12, which is installed at the wiring pattern 11 on the printed-wiring board and an electrode part of the electronic component 13 are connected via solder 15. A heat-receiving part 16, which is composed of a high- thermal-conductivity material, is installed to extend from the part 12 to the outer side from the arrangement area of the electronic component 13, and a jetting part 17 is installed at the boundary between the part 12 and the part 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an electronic component, and more particularly, to a structure for soldering an electrode of an electronic component to a connection pad on a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, there is a mounting structure as shown in FIG. 9 in which an electrode portion of an electronic component is electrically connected to a pad portion formed on a printed wiring board via solder. As shown in FIG. 9, a predetermined wiring pattern 1 and a plurality of connection pad portions 2 continuous with predetermined ends of the wiring pattern 1 are formed on the printed wiring board. These connection pad portions 2 are arranged so as to correspond to electrode portions (not shown) formed on the lower surface of the electronic component 3. Further, a solder paste is applied to the upper surface of the connection pad portion 2. As shown by a dashed line in FIG. 9, the electrode section 4 provided on the electronic component 3 is mounted on the plurality of connection pad sections 2. The connection pad 2 and the electrode 4 are connected to each other by applying infrared rays (IR) or hot air to the joint, or by reflowing the solder paste using both of them. When such a solder paste is melted, the wiring pattern 1 is covered with a resist 5 as shown by stippling in FIG. 10 to prevent the molten solder from flowing out to the wiring pattern 1 side. are doing.

[0003]

However, in the above-described electronic component mounting structure, when the wiring pattern 1 on the printed wiring board is large, or when the mounting area of the electronic component 3 or the electronic component 3 itself is large, the solder bonding is performed. Since the heat capacity of the connection pad portion 2 serving as a portion becomes large, the amount of heat required to melt the solder is likely to be insufficient. When the amount of heat is insufficient in this manner, phenomena such as unmelting of the solder and formation of fillet of the solder occur, and there is a problem that the solderability is deteriorated.

Accordingly, the present invention has been made to solve the above-mentioned problems, and is intended for use in a case where a wiring pattern on a printed wiring board is wide, or a mounting area of an electronic component or an electronic component itself is large. An object of the present invention is to provide an electronic component mounting structure having good solderability.

[0005]

According to a first aspect of the present invention, there is provided an electronic component in which a connection pad portion provided on a wiring pattern on a wiring board and an electrode portion of the electronic component are electrically connected via solder. Wherein a heat receiving portion made of a high thermal conductive material extends from the connection pad portion to an outside of an area where the electronic component is arranged.

In this electronic component mounting structure, when the electrode portion of the electronic component is set on the connection pad portion of the wiring board via paste-like solder and heated, the heat receiving portion efficiently absorbs heat energy, and The absorbed heat energy is transmitted directly to the connection pad, so that a large amount of heat energy is applied to the connection pad, which increases the speed of heating of the connection pad compared to when there is no heat receiving section, and starts melting the solder. As the time becomes shorter, the time during which the solder is in a molten state becomes longer.

According to a second aspect of the present invention, in the electronic component mounting structure according to the first aspect, the heat receiving portion is formed of the same material as the connection pad portion.

In this electronic component mounting structure, in addition to the function of the first aspect, the heat receiving portion can be formed in the same manufacturing process as the connection pad portion.

According to a third aspect of the present invention, there is provided the electronic component mounting structure according to the first or second aspect, wherein a jetty portion is formed at a boundary between the connection pad portion and the heat receiving portion. It is characterized by.

In this electronic component mounting structure, in addition to the effect of the first or second aspect of the present invention, the solder on the connection pad portion does not spread to the heat receiving portion.

According to a fourth aspect of the present invention, in the electronic component mounting structure according to the third aspect, the ridge portion is a resist having a melting temperature higher than a melting temperature of solder.

In this electronic component mounting structure, in addition to the effect of the third aspect of the present invention, the resist is not melted by the heat of the melted solder.

According to a fifth aspect of the present invention, there is provided the electronic component mounting structure according to any one of the first to fourth aspects, wherein the area of the heat receiving part is equal to the area of the connection pad part by 0.1. It is characterized in that it is 5 to 2.5 times.

In this electronic component mounting structure, the heat collection efficiency of the heat receiving portion is good, the heat supply efficiency to the connection pad portion is high, and the time to start melting the solder can be shortened.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention. FIG. 1 is a plan view showing the vicinity of a connection pad portion of a printed wiring board, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing a state where electronic components are soldered on a printed wiring board.

As shown in FIGS. 1 to 3, on a printed wiring board 10, a predetermined wiring pattern 11 and a plurality of connection pad portions 12 continuous to predetermined ends of the wiring pattern 11 are formed. ing. These connection pad portions 12
Are arranged so as to correspond to the electrode portions 14 formed on the lower surface of the surface-mounted electronic component 13. Connection pad part 1
A paste-like solder 15 is applied to the upper surface of 2.

The connection pad portion 12 has a square shape,
A heat receiving portion 16 having the same width extends from one end surface thereof, and the heat receiving portion 16 is arranged outside the area where the electronic component 13 is arranged. The length of the heat receiving portion 16 is preferably 0.5 to 2.5 times the length of the connection pad portion 12 in terms of thermal efficiency. The heat receiving portion 16 is made of the same material as the connection pad portion 12, and is made of a copper (Cu) foil which is a high heat conductive material. Also, the connection pad section 12 and the heat receiving section 1
A jetty portion 17 is provided at an upper surface position which is a boundary with the jetty 6. The jetty portion 17 is formed of a resist having a melting temperature higher than the melting temperature of the solder 15. On the upper surface of the wiring pattern 11, the molten solder 15
It is covered with a resist (not shown) to prevent it from flowing to one side.

Next, the soldering step will be described. The electrode section 14 of the electronic component 13 is set on the solder 15 of the connection pad section 12 of the printed wiring board 10. Next, infrared rays (I
R) and hot air are applied, or they are used in combination for heating. Then, the heat due to such heating is directly absorbed only in the portion located outside the electronic component 13 in the connection pad portion 12, while it is directly absorbed in the entire heat receiving portion 16. Then, the heat energy absorbed by the heat receiving unit 16 is directly transmitted to the connection pad unit 12. Therefore, a large amount of heat energy is applied to the connection pad portion 12, the speed of temperature rise of the connection pad portion 12 is increased as compared with the case where the heat receiving portion 16 is not present, and the melting start time of the solder 15 is shortened, and the solder 15 Since the time in the molten state becomes longer, even when the wiring pattern 11 on the printed wiring board 10 is wide, or when the mounting area of the electronic component 13 or the electronic component 13 itself is large, the temperature required for soldering is reduced. Solder melting time can be secured and solderability is good.

That is, in the present invention, since the heat receiving portion 16 is extended to the connection pad portion 12, the heat capacity as a whole of the solder joint increases, but instead, the ratio of the heat receiving area of the solder joint increases. Thus, the rate of temperature rise is improved by making the heat energy absorption much larger than in the conventional example.

In the first embodiment, the heat receiving section 16
Is formed of the same material as the connection pad portion 12, the heat receiving portion 16 can be formed in the same manufacturing process as the connection pad portion 12, so that the manufacturing process of the printed wiring board 10 is not complicated. .

Further, in the first embodiment, since the ridge 17 is formed at the boundary between the connection pad 12 and the heat receiving section 16, the solder 15 on the connection pad 12 is formed as shown in FIG. Since the solder 15 does not spread over the heat receiving portion 16, it is possible to prevent the solder 15 from getting wet to the electronic component 13 from being deteriorated or the fillet shape of the solder 15 being changed and the bonding strength from being reduced.

In the first embodiment, since the ridge 17 is a resist (not shown) having a melting temperature higher than the melting temperature of the solder 15, the resist is melted by the heat of the melted solder 15. Therefore, the spread of the solder 15 on the heat receiving portion 16 can be reliably prevented.

When lead-free solder (Ag, Cu, Sn base) is used as the solder 15, the melting point is Sn.
/ Pb eutectic solder (183 ° C.) in many cases. For example, in the case of Sn / Ag3.5, the melting point is 22.
In the case of 1 ° C. and Sn / Ag3.5 / Cu, the melting point is 217.
° C, Sn / Ag3.0 / Cu0.5, the melting point is 2
In the case of 18 ° C. and Sn / Ag 3.0 / Cu 0.7 / Bi 3.0, the melting point is 211 ° C. The soldering temperature has an upper limit due to the heat resistance of the printed wiring board 10 and the electronic components 13. If there is a wiring pattern 11 or an electronic component 13 on the printed wiring board 10 having a large heat capacity, the soldering of the connection pad portion 12 is conventionally performed. Although the melting time of No. 15 was shorter and the possibility of defective soldering was high, according to the present invention, the time required for soldering and the melting time of the solder can be secured as described above, so that lead-free Solder (Sn
Good soldering is also possible when using Ag, Cu,) for the base.

FIG. 4 shows a second embodiment of the present invention and is a plan view near a connection pad portion of a printed wiring board. FIG.
As shown in (2), the heat receiving portion 20 extends from the two end surfaces of the rectangular connection pad portion 12, and the heat receiving portion 20 is arranged outside the area where the electronic component 13 is arranged. An embankment portion 21 is provided in an L-shape at an upper surface position which is a boundary between the connection pad portion 12 and the heat receiving portion 20. The heat receiving section 20
As in the first embodiment, the connection pad 12 is made of copper (Cu) foil of the same material as the connection pad 12, and the jetty 21 is higher than the melting temperature of the solder 15 as in the first embodiment. It is formed of a resist having a melting temperature.

Since the other structure is the same as that of the first embodiment, the same components are denoted by the same reference numerals and the description is omitted.

In the second embodiment, the same operations and effects as those in the first embodiment can be obtained. Further, since the heat receiving portion 20 extends from the two end faces of the connection pad portion 12, the heat receiving portion 2
The heat transfer property from 0 to the connection pad portion 12 is good, and the temperature rising speed of the connection pad portion 12 is improved.

FIG. 5 shows a third embodiment of the present invention and is a plan view of the vicinity of a connection pad portion of a printed wiring board. FIG.
As shown in (1), a heat receiving portion 22 extends from an end surface of the rectangular connection pad portion 12 in three directions, and the heat receiving portion 22 is arranged outside the area where the electronic component 13 is arranged. In addition, a jetty portion 23 is provided in a U-shape at an upper surface position serving as a boundary between the connection pad portion 12 and the heat receiving portion 22. The heat receiving section 22
Similar to the first embodiment, the connection pad 12 is made of the same material as the copper (Cu) foil, and the jetty 23 is higher than the melting temperature of the solder 15 as in the first embodiment. It is formed of a resist having a melting temperature.

Since the other structure is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and the description is omitted.

According to the third embodiment, the same operation and effect as those of the first embodiment can be obtained. Further, since the heat receiving portion 22 extends from the three end surfaces of the connection pad portion 12, the second
Compared to the embodiment, the heat transfer from the heat receiving section 22 to the connection pad section 12 is further improved, and the temperature rising speed of the connection pad section 12 is further improved.

FIG. 6 shows a fourth embodiment of the present invention and is a plan view of the vicinity of a connection pad portion of a printed wiring board. FIG.
As shown in FIG. 5, a heat receiving portion 24 having the same width as the wiring pattern 11 extends from one end surface of the rectangular connection pad portion 12,
The heat receiving section 24 is arranged outside the area where the electronic components 13 are arranged. In addition, a jetty 25 is provided at an upper surface position which is a boundary between the connection pad section 12 and the heat receiving section 24. The heat receiving portion 24 is made of copper (Cu) foil of the same material as that of the connection pad portion 12 as in the first embodiment, and the jetty portion 25 is made of solder 15 as in the first embodiment. Is formed of a resist having a melting temperature higher than the melting temperature.

Since the other structure is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

In the fourth embodiment, the same functions and effects as those of the first embodiment can be obtained. Further, since the heat receiving portion 24 is formed using a part of the wiring pattern 11 as compared with the conventional example, it is not necessary to change the patterning shape of the connection pad portion 12 and the wiring pattern 11.

Further, since a part of the wiring pattern 11 is used, it is not necessary to secure an installation area for the heat receiving section 24 on a printed wiring board (not shown).

7 and 8 show a modification of the first embodiment. FIG. 7 is a cross-sectional view of the vicinity of a connection pad portion of a printed wiring board. FIG. 8 is a plan view of a vicinity of the connection pad portion of the printed wiring board. It is. This modified example is different from the first embodiment in that the paste 15 is applied to the electrode portions 14 of the electronic component 13 and soldered. Other configurations are the same as those of the first embodiment, and therefore, the same structural portions are denoted by the same reference numerals and description thereof will be omitted.

In each of the above embodiments, the case of reflow soldering has been described. However, the present invention is not limited to soldering in which a heating source is not in contact with the connection pad portion 12 or the like, such as light beam soldering. Applicable to the construction method.

[0037]

As described above, according to the first aspect of the present invention, the heat receiving portion made of a high thermal conductive material extends from the connection pad portion to the outside of the area where the electronic components are arranged. Heat energy is efficiently absorbed, and the absorbed heat energy is directly transmitted to the connection pad portion, so that a large amount of heat energy is applied to the connection pad portion. As the temperature rise speed rises, the melting start time of the solder becomes faster,
The time that the solder is in a molten state is prolonged. Therefore, even when the wiring pattern on the printed wiring board is wide, or the mounting area of the electronic component or the electronic component itself is large, the temperature required for soldering and the melting time of the solder can be secured, and the solderability is improved. good.

According to the second aspect of the invention, in addition to the effect of the first aspect, the heat receiving portion is formed of the same material as the connection pad portion. Can be created. Therefore, the manufacturing process of the wiring board is not complicated.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect of the present invention, a jetty portion is formed at the boundary between the connection pad portion and the heat receiving portion. It is possible to prevent the solder on the pad portion from spreading to the heat receiving portion, preventing the solder from getting wet to the electronic component, and preventing the solder from changing in fillet shape and reducing the bonding strength.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, the jetty portion is a resist having a melting temperature higher than the melting temperature of the solder. Is not melted, and it is possible to reliably prevent the solder from spreading to the heat receiving portion.

According to the invention set forth in claim 5, claims 1 to 5 are provided.
In addition to the effects of the invention described in claim 4, it is possible to optimize the heat collection efficiency of the heat receiving unit and the heat transfer efficiency to the connection pad unit.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention and is a plan view near a connection pad portion of a printed wiring board.

FIG. 2 shows the first embodiment of the present invention, and is a cross-sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view showing the first embodiment of the present invention and showing a state where an electronic component is soldered on a printed wiring board.

FIG. 4 is a plan view showing a second embodiment of the present invention, in the vicinity of a connection pad portion of a printed wiring board.

FIG. 5 is a plan view showing a third embodiment of the present invention, in the vicinity of a connection pad portion of a printed wiring board.

FIG. 6 is a plan view showing a fourth embodiment of the present invention, in the vicinity of a connection pad portion of a printed wiring board.

FIG. 7 is a cross-sectional view showing a modification of the first embodiment of the present invention and showing the vicinity of a connection pad portion of a printed wiring board.

FIG. 8 is a plan view showing a modification of the first embodiment of the present invention and showing the vicinity of a connection pad portion on a printed wiring board.

FIG. 9 is a plan view showing a conventional example and showing an arrangement relationship between connection pad portions on a printed wiring board and electrodes of an electronic component.

FIG. 10 is a plan view showing a conventional example, showing a main portion near a connection pad portion on a printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Printed wiring board (wiring board) 11 Wiring pattern 12 Connection pad part 13 Electronic component 15 Solder 16, 20, 22, 24 Heat receiving part 17, 21, 23, 25 Jetty part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroe Suzuki 206-1 Nunobikihara, Haibara-cho, Haibara-gun, Shizuoka Prefecture Inside Yazaki Parts Co., Ltd. F term in the company (reference) 5E314 AA25 BB09 BB11 FF01 GG26 5E319 AA03 AC16 BB05 CC33 GG03 5E336 AA04 CC31 EE03 GG06 5E338 CC10 CD11 CD33 EE51

Claims (5)

[Claims] An electronic component mounting structure in which a connection pad portion provided on a wiring pattern on a wiring board and an electrode portion of the electronic component are electrically connected via solder. A heat receiving portion made of a highly heat-conductive material extending from an area where the electronic component is arranged. 2. The electronic component mounting structure according to claim 1, wherein the heat receiving portion is formed of the same material as a connection pad portion. 3. The electronic component mounting structure according to claim 1, wherein a jetty portion is formed at a boundary between the connection pad portion and the heat receiving portion. Component mounting structure. 4. The mounting structure for an electronic component according to claim 3, wherein the jetty portion is a resist having a melting temperature higher than a melting temperature of the solder. 5. The mounting structure of an electronic component according to claim 1, wherein an area of the heat receiving section is 0.5 times an area of the connection pad section.
A mounting structure of an electronic component, which is 2.5 times as large.