JPH10303535A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the coating quantity of coating material partially by a method wherein a spacer whose height corresponds to the increased coating quantity is formed around a part where the coating quantity of the coating material is to be increased to form a clearance corresponding to the height of the spacer between a printed wiring board and a mask. SOLUTION: A solder resist layer 4 is formed around pads 2 and 3 and, further, a spacer 5 is formed around the pad 3. The height of the spacer 5 is determined in accordance with a printing thickness to be increased. When solder paste is printed, a metal mask 7 in which required patterns are opened is placed on a substrate 1 and the opening part 7a and an opening part 7b are aligned with the pad 2 and the pad 3 respectively. Solder paste is put on the metal mask 7 and a squeegee 9 is pressed against the solder paste and moved. As a clearance corresponding to the height of the spacer 5 is formed on the pad 3, it is printed with a solder paste 8b the printing thickness which is the sum of the thickness of the metal mask 7 and the height of the spacer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board for surface mounting, and more particularly to a method for applying a coating material such as a solder paste on a mounting surface by screen printing. The present invention relates to a printed wiring board capable of increasing the number of printed wiring boards.

[0002]

2. Description of the Related Art Conventionally, printed wiring boards for surface mounting (PW)
To apply the solder paste to B), a metal mask having a predetermined pattern of openings is placed on the printed wiring board, and a squeegee is moved on the solder paste placed on the metal mask. In this case, so-called screen printing, which is transferred onto the printed wiring board, is used, and the amount and thickness of the printed solder paste are determined by the thickness of the metal mask.

[0003] Incidentally, surface mounting components mounted on a printed wiring board vary in size, lead shape, flatness, and the like. Therefore, the amount of solder required for soldering these components is high. And solder thickness also vary. Therefore, when the solder paste is printed using a metal mask having a constant thickness, the thickness of the solder paste transferred onto the printed wiring board must be constant, and the amount of solder may be excessive or insufficient depending on the mounted component. This causes a soldering failure such as a bridge or unsoldering.
Therefore, various methods have been proposed to change the amount of solder depending on the component to be mounted.

In the first method, a metal mask whose thickness is partially changed by a half etching process or the like is used, and the solder paste placed on the metal mask is transferred onto a substrate by moving a squeegee. Is the way.

A second method is a screen printing method on substrates having different thicknesses, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-143860, which is equal to the difference in thickness between the mounting surfaces of the substrates. By providing a printing mask having a printing surface with a step, providing a separate squeegee for each different printing surface of the printing mask, by driving these squeegees,
This is a method of transferring cream solder on a print mask onto the substrate.

The third method is disclosed in, for example,
As disclosed in Japanese Unexamined Patent Publication No. 144596, when a metal mask formed with a hole having a predetermined pattern with a predetermined thickness is placed on a substrate, the contact surface of the metal mask with the substrate is A film having openings formed in the same pattern as the pattern is adhered by aligning the positions of both openings, and by changing the thickness of the film, the thickness of the cream solder transferred onto the substrate, that is, the solder It is a method of changing the amount.

[0007]

However, in the above-mentioned first method, since a metal mask having a partially changed thickness is used, the supply amount (application amount) of the solder paste varies. There was a point. The reason is that the solder paste has a missing property.

[0008] Generally, the solder paste has the following properties:
This is because, depending on the shape of the opening of the metal mask, the thicker the mask and the rougher the surface roughness of the cross section of the opening, the worse the tendency is. Variations in the supply amount of the solder paste cause soldering defects such as bridges and unsoldering when soldering small components or components with extremely small terminal spacing.

In the second method, since screen printing is rapidly performed on a substrate having mounting surfaces having different thicknesses, it is not possible to change the amount of cream solder to be applied to each different printing surface of a printing mask. Although it is possible, it is not possible to partially increase the amount of cream solder applied on the same printing surface.

In the third method, a film is adhered to the contact surface of the metal mask while aligning the positions of the openings. Therefore, by changing the thickness of the film, the amount of the cream solder to be applied can be increased. Can be changed as a whole, but the application amount of the cream solder cannot be partially increased.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to partially increase the application amount of a coating member such as a solder paste on a mounting surface by screen printing. It is to provide a printed wiring board which can be used.

[0012]

To solve the above problems, the present invention employs the following printed wiring board. In other words, the printed wiring board according to claim 1 is provided around a position on the mounting surface of the printed wiring board whose surface is a mounting surface, where the application amount of the coating member is to be increased among the positions where the coating member is to be applied. Further, a spacer having a height corresponding to the increasing application amount is provided.

According to a second aspect of the present invention, the height of the spacer is individually set in accordance with the application amount of each application member.

In the printed wiring board according to the first aspect, a spacer having a height corresponding to the increased coating amount is provided around a position where the coating amount of the coating member is to be increased, so that the coating member is coated. In addition, a clearance corresponding to the height of the spacer is formed between the printed wiring board and the mask, so that the application amount (thickness) of the application member to be applied can be partially increased.

In the printed wiring board according to the present invention, the height of the spacer is individually set in accordance with the application amount of each application member. Various clearances corresponding to the heights of the respective spacers are formed at different locations on the wiring board, and the application amount (thickness) of the application member applied using a mask having a constant thickness is increased for each location. It becomes possible.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the printed wiring board of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
1 is a partial cross-sectional view showing a printed wiring board according to an embodiment of the present invention. In the drawing, reference numeral 1 denotes a base material whose surface is a mounting surface and constitutes a main part of the printed wiring board; The amount of solder supplied at the time is not increased (the printed thickness of the solder does not increase). The pad 3 is formed on the same base material 1 and the amount of solder supplied at the time of printing is increased as compared with the pad 2 (the amount of the solder). Pad with increased print thickness).

Reference numeral 4 denotes a solder resist provided around the pads 2 and 3, and reference numeral 5 denotes a spacer formed of silk or the like and provided on the solder resist 4 around the pad 3. The height of the spacer 5 is arbitrary, but actually, the amount of solder (print thickness to be increased) to be increased according to the size of the component to be mounted, the shape of the lead, the flatness, and the like is set. The height is set according to the amount of solder to be printed (print thickness to be increased).

Next, a method of printing a solder paste (coating member) on the printed wiring board will be described with reference to FIG. First, as shown in FIG. 1A, a metal mask 7 having a predetermined pattern formed thereon is placed on the substrate 1 and then the alignment is performed.
Then, the opening portions 7b are aligned with the pads 3, respectively.

Next, an appropriate amount of the solder paste 8 is placed on the metal mask 7, and the squeegee 9 is pressed against the metal mask 7 in a state where the squeegee 9 is tilted forward at a predetermined angle in the traveling direction. To move. At this time, the metal mask 7 comes into close contact with the solder resist 4 by the printing pressure of the squeegee 9, and the solder paste 8 a having the same thickness as the metal mask 7 is printed on the pad 2.

On the other hand, a solder resist 4
Since a clearance corresponding to the height of the spacer 5 is generated between the metal mask 7 and the metal mask 7, the solder paste 8b having a thickness obtained by adding the height of the spacer 5 to the thickness of the metal mask 7 is printed.

Thereafter, as shown in FIG. 2B, when the metal mask 7 is peeled off, a solder paste 8 a having the same thickness as the metal mask 7 is formed on the pad 2, and a solder paste 8 a is formed on the pad 3. A solder paste 8b having a thickness obtained by adding the height of the spacer 5 to the thickness of the metal mask 7 is supplied.

As described above, according to the printed wiring board of the first embodiment, the amount of solder supplied at the time of printing on the solder resist 4 around the pad 3 is smaller than that of the other pads 2. Since the spacer 5 for increasing the amount (the printed thickness of the solder is increased) is provided, the amount of the solder (the printed thickness of the solder) supplied on the pad 3 can be arbitrarily increased.

Further, since the metal mask 7 having a constant thickness can be used, the supply amount of the solder paste 8 can be stabilized without changing the removability of the solder paste 8. Therefore, it is possible to prevent a soldering failure such as a bridge or unsoldering.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
FIG. 3 is a partial cross-sectional view showing the printed wiring board of the embodiment of the present invention. In the drawing, reference numeral 11 denotes a pad formed on the substrate 1 and supplied without increasing the amount of solder supplied during printing (the printed thickness of the solder does not increase); Reference numeral 12 denotes a pad formed on the base material 1 and supplied with an increased amount of solder to be supplied at the time of printing (the printed thickness of the solder is increased) as compared with the pad 11;
Is a pad in which the amount of solder supplied at the time of printing is further increased as compared with the pad 12.

Further, 14 is a solder resist provided around the pads 11 to 13, 15 is made of silk or the like,
The spacer 16 provided on the solder resist 14 around the pad 12 is a spacer provided on the solder resist 14 around the pad 13 and higher than the pad 15.

As in the first embodiment, the spacers 15 and 16 are used for increasing the amount of solder (print thickness to be increased) depending on the size of the component to be mounted, the shape of the lead, the flatness, and the like. Is set, and the height is set by the amount of solder to be increased (print thickness to be increased).

Next, a method of printing a solder paste (application member) on the printed wiring board will be described with reference to FIG. First, as shown in FIG. 1A, a metal mask 17 having a predetermined pattern formed thereon is placed on the substrate 1 and then the alignment is performed.
1, the opening 17b is adjusted to the pad 12, and the opening 17c is adjusted to the pad 13.

Next, an appropriate amount of solder paste 18 is placed on the metal mask 17, and the squeegee 9 is pressed against the metal mask 17 in a state where the squeegee 9 is tilted forward at a predetermined angle in the advancing direction. To move. At this time, the metal mask 17 is applied to the solder resist 1 by the printing pressure of the squeegee 9.
4 and the solder paste 18 a having the same thickness as the metal mask 17 is printed on the pad 11.

On the other hand, since a clearance corresponding to the height of the spacer 15 is generated between the solder resist 14 and the metal mask 17 on the pad 12, the thickness is obtained by adding the height of the spacer 15 to the thickness of the metal mask 17. Is printed. Similarly, on the pad 13, a clearance corresponding to the height of the spacer 16 higher than the spacer 15 is generated between the solder resist 14 and the metal mask 17. The solder paste 18c having the added thickness is printed.

Thereafter, as shown in FIG. 2B, when the metal mask 17 is peeled off, a solder paste 18a having the same thickness as the metal mask 17 is formed on the pad 11.
On the pad 12, a solder paste 18b having a thickness obtained by adding the height of the spacer 15 to the thickness of the metal mask 17 is provided.
A solder paste 18 having a thickness obtained by adding the height of the spacer 16 to the thickness of the metal mask 17 is provided on the pad 13.
c are each supplied.

As described above, according to the printed wiring board of the second embodiment, the amount of solder is increased on the solder resist 14 around the pad 12 as compared with the other pads 11 (the amount of the solder). (Print thickness increases) Spacer 1
5 and a solder resist 14 around the pad 13
Since the spacer 16 for increasing the amount of solder (the printed thickness of the solder is increased) is provided on the upper side, the amount of solder (printed thickness of the solder) to be supplied on each of the pads 12 and 13 is set to these pads. 12, 13 The amount can be increased according to individual requirements.

Further, since the metal mask 17 having a constant thickness can be used, the supply amount of the solder paste 18 can be stabilized without changing the plate removability of the solder paste 18. Therefore, it is possible to prevent a soldering failure such as a bridge or unsoldering.

[0034]

As described above, according to the printed wiring board of the first aspect of the present invention, the printed wiring board whose surface is the mounting surface is provided around the position where the application amount of the coating member of the printed wiring board is to be increased. Since a spacer having a height corresponding to the increasing application amount is provided, a clearance corresponding to the height of the spacer can be formed between the printed wiring board and the mask when applying the application member. Amount (thickness) of the applied member
Can be partially increased.

Further, since a mask having a constant thickness can be used, there is no change in the plate removability of the coating member.
The supply amount of the coating member can be stabilized. Therefore, it is possible to prevent a soldering failure such as a bridge or unsoldering.

According to the printed wiring board of the second aspect,
Since the height of the spacer was individually set in accordance with the application amount of each application member, when applying the application member, at a different position of the printed wiring board, the height of each spacer was matched. Various clearances can be formed, and the application amount (thickness) of the application member applied using a mask having a constant thickness can be increased for each location.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a process diagram showing a method for printing a solder paste (application member) on a printed wiring board according to the first embodiment of the present invention.

FIG. 3 is a partial cross-sectional view illustrating a printed wiring board according to a second embodiment of the present invention.

FIG. 4 is a process diagram showing a method for printing a solder paste (application member) on a printed wiring board according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 base material 2, 3 pad 4 solder resist 5 spacer 7 metal mask 7a, 7b opening 8, 8a, 8b solder paste (coating member) 9 squeegee 11-13 pad 14 solder resist 15, 16 spacer 17 metal mask 17a, 17b, 17c Open hole 18, 18a, 18b, 18c Solder paste

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/12 610 H05K 3/12 610L 3/34 505 3/34 505C

Claims (2)

[Claims] 1. A printed wiring board having a mounting surface whose surface is a mounting surface, wherein, among the positions on the mounting surface at which the coating member is to be coated, the coating amount increasing around the position at which the coating amount of the coating member is to be increased. A printed wiring board provided with a spacer having a height corresponding to the above. 2. The printed wiring board according to claim 1, wherein the height of the spacer is individually set in accordance with the amount of application of each application member.