JPH04332192A - Coating of cream solder on printed wiring board - Google Patents

Abstract

PURPOSE:To enable use of different kinds of cream solders for coating on a fine electrode pattern and an ordinary electrode pattern. CONSTITUTION:Coating of cream solder on a fine electrode pattern 9 using a thin mask material is conducted in different process from printing of a cream solder using a cream solder printing metal mask 2 having an electrode aperture 3 to the position of an ordinary electrode pattern 8 and a recess 4 to the position of a fine electrode pattern 9 in such a side of the metal mask 2 as in contact with a printed wiring board 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying cream solder to a printed wiring board, which is necessary when surface-mounted electrical components are soldered to the printed wiring board.

0002

2. Description of the Related Art FIG. 8 is a sectional view of a conventional cream solder metal mask, which has an opening 3 and a fine opening 16 in a mask portion 2. FIG. 9 is a cross-sectional view of a printed wiring board coated with cream solder using a conventional cream solder metal mask, and shows a normal electrode pattern 8 of a printed wiring board 5 provided with a normal electrode pattern 8 and a fine electrode pattern 9. Cream solder 6 and minute cream solder 7 are formed on the fine electrode pattern 9.

Next, the operation will be explained. The cream solder is applied to the openings 3 and fine openings 1 provided in the mask part 2.
6, cream solder 6 and fine cream solder 7 are simultaneously formed on the electrode pattern 8 and fine electrode pattern 9 of the printed wiring board 5.

0004

[Problems to be Solved by the Invention] The conventional method of applying cream solder uses a mask as described above, so only one type of cream solder can be used. There was a problem in that it was not possible to select a cream solder with the optimum solder particle shape, solder particle size, viscosity, etc. for each part 16.

[0005] This invention was made to solve the above-mentioned problems, and by performing cream solder printing multiple times using different metal mask thicknesses and cream solder optimal for the metal mask thickness, The purpose is to supply high-quality cream solder shapes to electrode patterns provided on printed wiring boards.

[0006]

[Means for Solving the Problems] The cream solder application method according to the present invention includes a first step of applying cream solder only to a fine electrode pattern, and a metal mask having a concave portion from which the already applied cream solder escapes. The second step is to apply cream solder to the electrode pattern using a conventional method.

[0007]

[Operation] According to the cream solder application method of the present invention, cream solder that is thicker than the cream solder that has already been applied is applied to a different electrode pattern while maintaining the shape of the already applied minute cream solder in terms of quality. Can be applied.

[0008]

【Example】

Example 1. In FIGS. 1 and 2, 1 is a mask frame, 2
is a mask portion fixed to the mask frame 1; 3 is an opening provided in the mask portion 2; and 4 is a recess provided in the printed wiring board of the mask portion 2.

Next, a cream solder printing procedure using the present invention will be described. In the first step, a thin mask material 15 having minute openings 16 shown in FIG. It passes through the fine openings 16 and is applied onto the printed wiring board 5. After applying the cream solder, the thin mask material 15 is vertically removed from the printed wiring board 5. For cream solder printing, a squeegee (not shown) is used to adjust the amount of cream solder to the thickness of the thin mask material 15.
Use.

FIG. 6 shows a state in which minute cream solder 7 is applied to minute electrode pattern 9 on printed wiring board 5. As shown in FIG. In this step, cream solder is not usually applied to the electrode pattern 8. FIG. 7 shows the state of cream solder printing in the second step. In this step, a cream solder 6 different from that in the first step is printed on the normal electrode pattern 8 of the printed wiring board 5. The fine cream solder 7 applied in the first step is shown in Figure 2.
The shape is protected by the recess 4 of the mask 2 shown in FIG. After printing, the metal mask 2 is vertically removed from the printed wiring board 5.

FIG. 3 shows the printed wiring board after applying cream solder in the second step. Cream solder 6 and minute cream solder 7 are applied on the normal electrode pattern 8 and fine electrode pattern 9 of the printed wiring board 5, and different cream solder 6 and minute cream solder 7 are used.

Among the printed wiring board assembly manufacturing methods, in the cream solder printing method, the amount of cream solder supplied must be optimized according to the shape of the component electrodes in order to ensure the soldering quality of the components mounted on the printed wiring board. In addition, the minimum width of the opening of the metal mask is determined by the thickness of the metal mask because of the ease with which cream solder can be removed from the opening.

[0013] When supplying minute cream solder, it is necessary to have a minute opening in the metal mask, and a thin metal mask thickness suitable for the minute opening is required. When using this method, cream solder smudges on the minute cream solder on the fine electrode pattern, making it impossible to stably supply the optimum amount of cream solder.

[0014] In order to stably supply fine cream solder to the fine electrode pattern, it is necessary to change the cream solder to one with granularity suitable for the thickness of the metal mask.

Example 2. Note that FIG. 2 used in Example 1 above
Instead of the mask shown in FIG. 4, the entire mask is composed of two layers, and an upper mask material 10 and a lower mask material 11 are provided with an upper opening 12, a lower opening 13, and a lower opening 14,
The same shape may be used by laminating the upper mask material 10 and the lower mask material 11 together.

[0016]

[Effects of the Invention] According to the present invention, since cream solder printing can be performed in multiple steps, the optimal cream solder can be selected for each different cream solder metal mask thickness, and a high quality cream solder printed shape can be obtained. effective.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a second metal mask used in the present invention.

FIG. 2 is a cross-sectional side view of the mask portion of FIG. 1;

FIG. 3 is a cross-sectional side view of a printed wiring board coated with cream solder according to the present invention.

FIG. 4 is a cross-sectional side view of another shaped second mask portion used in the present invention.

FIG. 5 is a cross-sectional side view of a first metal mask used in the present invention.

FIG. 6 is a cross-sectional side view of a printed wiring board coated with cream solder in the first step of the present invention.

FIG. 7 is a cross-sectional side view of a printed wiring board showing a second step of the invention.

FIG. 8 is a cross-sectional side view of a mask portion of a conventional cream solder metal mask.

[Figure 9] Using a conventional cream solder metal mask,
FIG. 2 is a cross-sectional side view of a printed wiring board coated with cream solder.

[Explanation of symbols]

1 Mask frame 2 Mask part 3 Opening 4 Recessed part 5 Printed wiring board 6 Cream solder 7. Micro cream solder 8 Normal electrode pattern 9 Fine electrode pattern 10 Upper mask material 11 Lower mask material 12 Upper opening 13 Lower opening 14 Lower opening 15 Thin mask material 16 Fine opening

Claims (1)

[Claims] 1. When applying cream solder on the pattern of a printed wiring board in which a fine electrode pattern and a normal electrode pattern are formed on the same printed wiring board, a first solder having an opening corresponding to the fine electrode pattern is applied. The first step is to apply cream solder onto the fine electrode pattern using a metal mask, which is thicker than the first metal mask, and has an opening corresponding to the normal electrode pattern, and a solder paste on the already applied fine electrode pattern. A method for applying cream solder to a printed wiring board, which comprises a second step of applying cream solder onto a normal electrode pattern using a second metal mask having a recessed portion through which the cream solder escapes.