JP2008205101A - Manufacturing method of electronic component mounted substrate and electronic component mounted substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electronic component mounted substrate capable of reducing poor connection between an electronic component and a printed wiring board and preventing occurrence of a solder ball, and the electronic component mounted substrate. <P>SOLUTION: The manufacturing method includes steps of forming a land 12 and a solder resist 16 having a first opening 14 and a second opening 15 for exposing the land on a base material 18 to prepare a printed wiring board 10, applying cream solder 20 to the printed wiring board, then mounting an electronic component via the cream solder, heating the printed wiring board to a predetermined temperature and further cooling it to obtain the electronic component mounted substrate. When the solder resist is formed, the first opening is formed in a predetermined range on the land and the second opening is formed to surround the first opening outside the periphery of the first opening on the land, and in addition, the cream solder is applied to an area where the first and second openings are formed and to an area where the solder resist extends between the first and second openings. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component mounting board manufacturing method and an electronic component mounting board, and more particularly, to an electronic component mounting board manufacturing method and an electronic component mounting board for mounting a surface mounting type electronic component on a printed wiring board by soldering. .

In recent years, along with the downsizing of electronic equipment and high-density mounting, electronic parts mounted on printed wiring boards have been downsized and the pitch of electronic component leads has been reduced. Surface-mounted electronic components that can be independently mounted on both sides of a board are widely used.
Patent Document 1 describes an example of a method for manufacturing an electronic component mounting board in which such a surface mounting type electronic component is mounted on a printed wiring board by soldering.
Japanese Patent Laid-Open No. 04-177772

Here, the problem of the manufacturing method of the conventional electronic component mounting substrate as described in Patent Document 1 will be described with reference to FIGS.
5 and 6 are schematic cross-sectional views for explaining a first problem and a second problem of the conventional method of manufacturing an electronic component mounting board, respectively, and (a) in each figure shows a state before mounting. , (B) shows the state after mounting, respectively.

First, a semiconductor package 100 that is a surface-mount type electronic component and a printed wiring board 110 on which the semiconductor package 100 is mounted will be described as components for manufacturing a conventional electronic component mounting substrate 150 described later.
As shown in FIG. 5A, the semiconductor package 100 mainly includes a main body portion 101 in which a semiconductor element is molded with a resin, a lead portion 102 that is electrically connected to the semiconductor element, and when the semiconductor element is driven. The heat dissipation electrode 103 is used to efficiently dissipate heat generated from the semiconductor element.
The printed wiring board 110 mainly includes a base material 118, a first land portion 111 that is formed on the base material 118 and is connected to the lead portion 102 via a solder 121 described later, and the solder 121. A second land portion 112 connected to the heat radiation electrode 103, a first opening 113 formed so as to expose the first land portion 111, and a second land portion 112 exposed. And a solder resist 115 that covers the surface of the printed wiring board 110 in a range other than the first opening 113 and the second opening 114.

  Next, an electronic component mounting board manufacturing method for manufacturing the electronic component mounting boards 150 and 160 by mounting the semiconductor package 100 on the printed wiring board 110 using the cream solder 120 will be described.

  First, the cream solder 120 is printed on the first land portion 111 and the second land portion 112 of the printed wiring board 110 using the metal mask 122. At this time, the application range of the cream solder 120 is set to the solder resist 115. A problem in the case of corresponding to the opening ranges of the first opening 113 and the second opening 114 will be described.

First, as shown in FIG. 5 (a), the cream solder 120 is applied so that the application range of the cream solder 120 corresponds to the opening ranges of the first opening 113 and the second opening 114 of the solder resist 115. It is applied to the first land portion 111 and the second land portion 112.
Next, after placing the semiconductor package 100 on the printed wiring board 110 via the applied cream solder 120, the printed wiring board 110 is heated to melt the solder 121 in the cream solder 120. By cooling and solidifying the melted solder 121, an electronic component mounting board 150 in which the semiconductor package 100 is mounted on the printed wiring board 110 is obtained as shown in FIG.

However, in general, in the semiconductor package 100, the soldering position of the lead part 102 is located on the outer side from the main body part 101, that is, on the printed wiring board 110 side as compared with the soldering position of the heat radiation electrode 103. In the electronic component mounting substrate 150, the distance between the heat radiation electrode 103 of the semiconductor package 100 and the second land portion 112 of the printed wiring board 110 is wider than the distance between the lead portion 102 and the first land portion 111. The heat radiation electrode 103 and the second land portion 112 may not be connected by the solder 121 in some cases.
When the heat dissipation electrode 103 of the semiconductor package 100 and the second land portion 112 of the printed wiring board 110 are not connected by the solder 121, the heat generated from the semiconductor element when the semiconductor element of the semiconductor package 100 is driven is second. Since it is difficult to efficiently dissipate heat to the land portion 112, a malfunction such as malfunction of the semiconductor element or shortening of the life of the semiconductor element occurs.
This defect is referred to as a first problem.

Therefore, means for increasing the amount of the cream solder 120 applied to the second land portion 112 so that the heat radiation electrode 103 of the semiconductor package 100 and the second land portion 112 of the printed wiring board 110 can be connected by the solder 121. Conceivable.
By the way, since the thickness of the metal mask 122 for printing the cream solder 120 is usually uniform in the plane, in order to increase the application amount of the cream solder 120 to the second land portion 112, FIG. As shown in FIG. 6, a method of applying the cream solder 120 by expanding the application range to a range wider than the opening range of the second opening 114 of the solder resist 115 is conceivable.
In FIG. 6, the same components as those in FIG. 5 described above are denoted by the same reference numerals.

However, as shown in FIG. 6B, in the electronic component mounting board 160 manufactured by this method, the heat dissipation electrode 103 of the semiconductor package 100 and the second land portion 112 of the printed wiring board 110 are connected by solder 121. Although the solder can be connected, the cream solder 120 is also applied onto the solder resist 115. Therefore, after the solder 121 in the cream solder 120 is melted and further individualized, the solder 121 is placed on the solder resist 115. Some of the solder balls 121a may be generated.
The solder balls 121a may cause a short circuit between the leads of the semiconductor package 100.
This generation of solder balls is referred to as a second problem.

  Therefore, the problem to be solved by the present invention is to provide a method for manufacturing an electronic component mounting board and an electronic component mounting board that can reduce the connection failure between the electronic component and the printed wiring board and prevent a short circuit failure due to a solder ball. It is in.

In order to solve the above problems, each invention of the present application has the following means.
1) A method of manufacturing an electronic component mounting board (50) for manufacturing an electronic component mounting board (50) in which the electronic component (1) is mounted on a printed wiring board (10). Forming a solder resist (16) having a first opening (14) and a second opening (15) so that the land portion is exposed, and the printed wiring board. A printed wiring board manufacturing step, a coating step of applying cream solder (20) to the printed wiring board after the printed wiring board manufacturing step, and the electronic component on the printed wiring board after the applying step. Soldering process for obtaining the electronic component mounting board by placing the cream through the solder paste, heating the printed wiring board on which the electronic component is placed to a predetermined temperature, and then cooling the printed wiring board In the printed wiring board manufacturing step, the first opening is formed in a predetermined range on the land portion, and the second opening is the first opening on the land portion. The first opening and the solder resist are formed so as to surround the first opening on the outer side of the peripheral portion, and the first opening and the second opening are formed in the coating step. Is a method of manufacturing an electronic component mounting board, wherein the cream solder is applied in a range interposed between the first opening and the second opening.
2) In the electronic component mounting board on which the electronic component (1) is mounted on the printed wiring board (10), the printed wiring board includes a base material (18) and a land portion (12) provided on the base material. And a first opening (14) provided on the base material and exposed in a predetermined range on the land portion to expose the land portion, and the first opening portion on the land portion. And a solder resist (16) having a second opening (15) that is provided outside the peripheral portion of the first opening to surround the first opening and exposes the land. Is an electronic component mounting board (50) characterized by being electrically connected to the electronic component in the first opening.

  According to the present invention, there is an effect that connection failure between an electronic component and a printed wiring board is reduced, and short circuit failure due to a solder ball can be prevented.

The preferred embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.
1 and 2 are schematic cross-sectional views for explaining a first step and a second step in the method of manufacturing an electronic component mounting board and the embodiment of the electronic component mounting board of the present invention, respectively.

<Example>
[First step] (See Fig. 1)
First, a semiconductor package 1 that is a surface-mount type electronic component and a printed wiring board 10 on which the semiconductor package 1 is mounted will be described as components for manufacturing an electronic component mounting board 50 described later.

As shown in FIG. 1A, the semiconductor package 1 mainly includes a main body portion 2 in which a semiconductor element is molded with a resin, a lead portion 3 electrically connected to the semiconductor element, and when the semiconductor element is driven. The heat dissipation electrode 4 is configured to efficiently dissipate heat generated from the semiconductor element.
Further, as shown in FIG. 1B, the printed wiring board 10 is mainly connected to the lead portion 3 via a base material 18 and solder 21 described later formed on the base material 18, respectively. 1 land portion 11, a second land portion 12 connected to the heat radiation electrode 4 via the solder 21, and an opening formed so as to expose the first land portion 11 and the second land portion 12. And a solder resist 16 that covers the surface of the printed wiring board 10 excluding a range where the openings 13, 14, 15 are formed.
Here, for convenience, the opening 13 formed so that the first land portion 11 is exposed is referred to as the first opening 13, and the openings 14 and 15 formed so that the second land portion 12 is exposed. These are referred to as the second opening 14 and the third opening 15, respectively.
In the first land portion 11, the first region A <b> 13 exposed by the first opening 13 becomes a first connection region A <b> 13 connected to the lead portion 3 of the semiconductor package 1.

Here, the 2nd land part 12, the 2nd opening part 14, and the 3rd opening part 15 are explained in detail using inset A1 in Drawing 1 (b) and Drawing 1 (b). The inset A1 is a plan view when the vicinity of the second land portion 12 is viewed from above in FIG.
As shown in FIG. 1B and its insertion diagram A1, the second opening portion 14 and the third opening portion 15 are provided on the second land portion 12, respectively. The third opening 15 is divided into four so as to surround the second opening 14 in the vicinity of the outer periphery of the second land 12 at the substantially central portion of the second land 12. .
In the second land portion 12, the second region A 14 exposed by the second opening 14 becomes a second connection region A 14 connected to the heat radiation electrode 4 of the semiconductor package 1, and the third opening 15 The exposed third region B14 becomes a solder reservoir B14 that prevents the generation of solder balls when a solder 21 in cream solder 20 described later is melted and further individualized.

[Second step] (See Fig. 2)
First, as shown in FIG. 2A, cream solder 20 is applied to the printed wiring board 10 by a printing method using a metal mask 22.
Specifically, the cream solder 20 is applied in substantially the same range as the first area A13, and the second area A14, the third area B14, and the solder resist 16 are interposed between the areas A14 and B14. Apply to approximately the same range.
Here, (a) in FIG. 2 shows a state before mounting, and (b) shows a state after mounting.
The cream solder 20 is obtained by kneading a plurality of particulate solders 21 into a flux, and a commercially available product can be used.

Next, the semiconductor package 1 is placed on the printed wiring board 10 to which the cream solder 20 is applied.
Specifically, the lead portion 3 of the semiconductor package 1 and the first region A13 of the printed wiring board 10 are aligned, and the heat radiation electrode 4 and the second region A14 are aligned to print the semiconductor package 1. Placed on the wiring board 10.

  By the way, the semiconductor package 1 is located on the outer side from the main body 2, that is, on the printed wiring board 10 side as compared with the soldering position of the heat radiation electrode 4. Is placed on the printed wiring board 10, the distance between the heat radiation electrode 4 of the semiconductor package 1 and the second land portion 12 of the printed wiring board 10 is larger than the distance between the lead portion 3 and the first land portion 11. It is getting wider.

  Thereafter, the printed wiring board 10 on which the semiconductor package 1 is placed is heated to a temperature higher than the melting point of the solder 21 in the cream solder 20 by using a reflow furnace, and the solder 21 is melted. By cooling and solidifying the solder 21 thus obtained, an electronic component mounting substrate 50 in which the semiconductor package 1 is mounted on the printed wiring board 10 as shown in FIG. 2B is obtained.

In the electronic component mounting substrate 50, the lead portion 3 of the semiconductor package 1 and the first land portion 11 of the printed wiring board 10 are connected by the solder 21 in the first connection region A13. The two land portions 12 are connected by the solder 21 in the second connection region A14.
Here, for convenience, the solder 21 in the first connection region A13 is referred to as a first solder portion 21a, and the solder 21 in the second connection region A14 is referred to as a second solder portion 21b.

According to the electronic component mounting board manufacturing method and the electronic component mounting board described above, when the solder 21 is melted in the second step of the embodiment, the solder 21 in the vicinity of the second connection region A14 on the solder resist 16 is Since it is taken into the second solder part 21b by the surface tension, the amount of solder of the second solder part 21b can be increased as compared with the prior art.
Accordingly, when the semiconductor package 1 is placed on the printed wiring board 10, the distance between the heat radiation electrode 4 of the semiconductor package 1 and the second land portion 12 of the printed wiring board 10 is such that the lead portion 3 and the first land portion 11. Even when the gap is larger than the distance between the heat dissipation electrode 4 and the second land portion 12, it is possible to connect the second land portion 12 with the solder 21, so that the first problem described above can be solved.

In addition, according to the method for manufacturing an electronic component mounting board and the electronic component mounting board described above, the melted solder 21 in a range away from the vicinity of the second connection region A14 on the solder resist 16 has a solder pool portion due to its surface tension. Accumulate in B14. The solder 21 collected in the solder pool portion B14 is referred to as a third solder portion 21c.
Therefore, when the solder 21 is melted, the solder 21 on the solder resist 16 is taken into the second solder portion 21b or the third solder portion 21c, so that the generation of solder balls on the solder resist 16 is prevented. Therefore, it is possible to prevent a short circuit failure due to a solder ball and solve the second problem described above.

  The embodiment of the present invention is not limited to the configuration and procedure described above, and it goes without saying that modifications may be made without departing from the scope of the present invention.

  For example, in the embodiment, a semiconductor package having a lead portion has been described as an example of a surface-mount type electronic component mounted on a printed wiring board. However, the present invention is not limited thereto, and is not limited to this. It is also possible to use surface mount type electronic components having other forms.

<Modification>
Here, a modification of the above-described embodiment will be described with reference to FIGS.
3 and 4 are diagrams for explaining a modification of the method for manufacturing an electronic component mounting board and the embodiment of the electronic component mounting board according to the present invention. FIG. 3 shows a state before mounting, and FIG. Each subsequent state is shown. Moreover, (a) in each figure is a perspective view, (b) is typical sectional drawing when it sees from the arrow B in (a).

As shown in FIG. 3, in the modification, a module component 200 is used as a surface mount electronic component instead of the semiconductor package of the embodiment.
The module component 200 mainly includes a base 201 and a main body 202 in which an active element such as a semiconductor element and a passive element such as a capacitor are molded on the base 201 with a resin or the like.
A terminal portion 204 connected to a land portion 212 of a printed wiring board 210 to be described later is formed on the side surface of the base 201.
The terminal portion 204 has a substantially semi-cylindrical shape that is recessed toward the center of the base 201 and is generally referred to as an end face through or end face through terminal.
The base 201 can be manufactured using a known printed wiring board process or ceramic wiring board process.
The module component 200 described above is a so-called leadless type surface-mount electronic component having no lead portion.

The printed wiring board 210 on which the module component 200 is mounted mainly includes a base material 211, a land part 212 formed on the base material 211 and connected to the terminal part 204 of the module part 200, and the land part 212 is exposed. And a solder resist 215 having a fourth opening 213 and a fifth opening 214.
In the modification, the shapes of the land portion 212, the fourth opening portion 213, and the fifth opening portion 214 are changed to the second land portion 12, the second opening portion 14, and the third opening portion 15 of the embodiment. The shape of each was the same.

Next, cream is applied to the area where the fourth opening 213 and the fifth opening 214 are formed, and to the area where the solder resist 215 is interposed between the fourth opening 213 and the fifth opening 214. The solder 20 is printed, the terminal portion 204 of the module component 200 and the land portion 212 of the printed wiring board 210 are aligned, and the module component 200 is placed on the printed wiring board 210.
Thereafter, the printed wiring board 210 is heated to a temperature higher than the melting point of the solder 21 in the cream solder 20 by using a reflow furnace to melt the solder 21, and further, the molten solder 21 is cooled and solidified. By doing so, an electronic component mounting board 250 in which the module component 200 is mounted on the printed wiring board 210 as shown in FIG. 4 is obtained.
Further, the fifth opening 214 becomes a solder reservoir 214.

When the leadless surface-mount type electronic component such as the module component 200 described above is heated in a reflow furnace, the center portion is convex toward the printed wiring board 210 as shown in FIG. May be warped.
When the module component 200 is warped by heating, the distance between the terminal portion 204 of the module component 200 and the land portion 212 of the printed wiring board 210 becomes larger than before heating. For the same reason as described above, the supply amount of the solder 21 to the land portion 212 can be increased as compared with the conventional case. Therefore, the terminal portion 204 of the module component 200 and the land portion 212 of the printed wiring board 210 can be securely connected by the solder 21. In addition, it is possible to prevent short-circuit defects caused by solder balls.

In the embodiment and the modified example, the shape of the solder pool portions B14 and 214 is divided into four parts, but the shape is not limited to this, and the solder pool portions B14 and 214 are in a range away from the vicinity of the second connection region A14 on the solder resist 16. Any shape that can take in solder may be used.
For example, the shape of the solder pool portion other than the embodiment and the modified example may be divided into two or more parts so as to surround the second connection region A14, or may be a ring shape surrounding the second connection region A14. It is good.

  In the embodiment and the modification, the planar shape of each of the second land portion 12 and the land portion 212 is a circular shape. However, the present invention is not limited to this, and the first opening portion is within a predetermined range on the land. And the second opening can be formed outside the outer periphery of the first opening so as to surround the first opening. For example, instead of the circular shape, a rectangular shape or many It can be made into arbitrary shapes, such as a square shape.

It is typical sectional drawing for demonstrating the 1st process in the Example of the manufacturing method of the electronic component mounting board | substrate of this invention, and an electronic component mounting board | substrate. It is typical sectional drawing for demonstrating the 2nd process in the Example of the manufacturing method of the electronic component mounting board | substrate of this invention, and an electronic component mounting board | substrate. It is the perspective view and schematic sectional drawing for demonstrating the modification with respect to the manufacturing method of the electronic component mounting board | substrate of this invention, and the Example of an electronic component mounting board | substrate. It is the perspective view and schematic sectional drawing for demonstrating the modification with respect to the manufacturing method of the electronic component mounting board | substrate of this invention, and the Example of an electronic component mounting board | substrate. It is typical sectional drawing for demonstrating the subject of the manufacturing method of the conventional electronic component mounting board | substrate. It is typical sectional drawing for demonstrating the subject of the manufacturing method of the conventional electronic component mounting board | substrate.

Explanation of symbols

1 semiconductor package, 2 body part, 3 lead part, 4 heat radiation electrode,
DESCRIPTION OF SYMBOLS 10 Printed wiring board, 11,12 Land part, 13,14,15 Opening part, 16 Solder resist, 18 Base material, 20 Cream solder, 21 Solder, 22 Metal mask, 50 Electronic component mounting board, A13, A14 Connection area, B14 Solder pool

Claims (2)

An electronic component mounting board manufacturing method for manufacturing an electronic component mounting board in which an electronic component is mounted on a printed wiring board,
A printed wiring board for producing the printed wiring board by forming a land portion on a substrate and further forming a solder resist having a first opening and a second opening so that the land portion is exposed. Production process;
After the printed wiring board manufacturing step, an application step of applying cream solder to the printed wiring board;
After the coating step, the electronic component is placed on the printed wiring board via the cream solder, the printed wiring board on which the electronic component is placed is heated to a predetermined temperature, and then the printed wiring board is cooled. A soldering step for obtaining the electronic component mounting board,
Have
In the printed wiring board manufacturing step, the first opening is formed in a predetermined range on the land portion, and the second opening is formed more than the peripheral portion of the first opening on the land portion. Forming outside to surround the first opening,
In the coating step, a range in which the first opening and the second opening are formed, and a range in which the solder resist is interposed between the first opening and the second opening. And applying the cream solder to the electronic component mounting board. In the electronic component mounting board where the electronic component is mounted on the printed wiring board,
The printed wiring board is
A substrate;
A land portion provided on the substrate;
More than the first opening provided on the base material and in a predetermined range on the land portion to expose the land portion, and the peripheral portion of the first opening on the land portion A solder resist having a second opening provided on the outside so as to surround the first opening and exposing the land part;
With
The electronic component mounting board, wherein the land portion is electrically connected to the electronic component in the first opening.

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