JPS61229387A - Solder paste printing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a printing method for accurately applying solder paste to a component mounting pattern on a printed circuit board, particularly to a fine and highly accurate pattern.

[Background of the invention]

Conventionally, as a method for supplying solder paste onto the parts mounting pattern of a printed board, a printing plate with holes that match the pattern is placed on the printed board, and the solder paste placed on the printing plate is swept with a squeegee. It is known to supply solder paste to the pattern through holes in the plate.

FIG. 2 is a diagram schematically showing this method, and FIG. 3 is an enlarged side view showing the printing plate 2 and the printed circuit board 1 in cross section. The printing plate 2 is set with an appropriate gap between it and the printed circuit board 1, and when the solder paste 4 is swept over the printing plate 2 with the squeegee 3, the printing plate 2 is attached to the printed circuit board 1.
At the same time, the solder paste 4 is supplied to the hole 6 of the printing plate 2, and after the squeegee 3 passes through the hole 6 corresponding to the component mounting pattern 5, the printing plate 2 closes the original gap with the printed circuit board l. The solder paste 4 can be applied on the one-component mounting pattern 5 after returning to the state where it was placed.

However, as shown in the side view of FIG. 3 or the plan view of FIG. 4, this method has a problem in that the solder paste 4 does not enter the holes 6 sufficiently, resulting in so-called chipping. Further, it is necessary to delicately adjust the pressure applied by the squeegee 3 and to adjust the angle of the squeegee 30.

As a prior art in this field, for example, Japanese Patent Application Laid-open No. 1987-
There is a technique described in Japanese Patent No. 112096 [Object of the Invention] An object of the present invention is to provide a method for printing solder paste that can supply a sufficient and always constant amount of solder paste to a component mounting pattern on a printed board. It's about doing.

[Summary of the invention]

Conventionally, when supplying solder paste onto the component mounting pattern via a printing plate, the height and amount of paste was not constant because of a problem with the squeegee of the printing device, and the squeegee angle of the printing pressure Various studies have been conducted on the paste particles, the viscosity of the solder paste, the cross-sectional shape of the mask, etc., but when printing plates become as fine as in recent years, the solder paste does not enter the holes sufficiently, resulting in print defects. The present invention addresses this problem by arranging two squeegees in parallel.

That is, the present invention supplies solder paste to the through-holes of the printing plate using the first squeegee while the printing plate is in close contact with the printed circuit board by sweeping two squeegees arranged in parallel. , the solder paste printing method is characterized in that the solder paste is then supplied again to the same through hole using a second squeegee.

[Embodiments of the invention]

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

FIG. 1 is an enlarged side view of the printing apparatus showing a printing plate 2 and a printed circuit board 1 in cross section. The squeegee 3-1 and the squeegee 3-2 are two squeegees arranged in parallel.

The printing plate 2 is a printing mask having a thickness of, for example, about 0.2 to 0.25111 mm, and has holes 6 penetrating through the printed circuit board 1 at positions corresponding to the component mounting patterns 5.

Next, the method of this example will be explained. First, the printing plate 2 is set at the position A in FIG. 1, which is spaced apart from the printed circuit board 1 by ΔS. ΔS is, for example, the 11th position. Next, place the solder paste 4 in front of each of the two squeegees 3-1 and 3-2, and then
1.3-2 is moved integrally over the printing plate 2 to sweep the solder paste 4, and as the squeegee 3-1.3-2 moves, the printing plate 2 descends and comes into close contact with the printed circuit board 1. ΔS becomes O (position shown in FIG. 1B).

In this state, first squeegee 3-
1 supplies the solder paste 4, and then the squeegee 3-2 supplies the solder paste 4. That is, the same hole 6 is coated with solder paste 4 twice, and as a result, a sufficient amount of solder paste 4 is applied to the hole as shown in the side view of FIG. 1 or the top view of FIG. 6, and so-called chipping does not occur. When the squeegee 3-1.3-2 passes through the hole 6, the deflection of the printing plate 2 is corrected and it returns to the initial position, and the supply of solder paste 40 to the component mounting pattern 5 is completed. Even if one squeegee 3 is used, solder paste can be applied 402 times. However, in this case, after the first sweep of the solder paste 4, the printing plate 2 returns to the top, and the second sweep of the solder paste 4 lowers the printing plate 2 again and applies the second solder paste 4 to the same hole 6. Supplied. In this case, a second supply of solder paste 4 is performed on the solder paste 4 cut out by the first sweep and spread on the component mounting pattern 5. The solder paste 4 that is piled up loses its shape and does not achieve its purpose.

After the first squeegee 3-1 passes through the hole 6 while supplying the solder paste 4, the next squeegee 3-1 passes through the hole 6 while the printing plate 2 is still in close contact with the printed circuit board 1.
2, the point of the present invention is that the solder paste 4 is supplied to the same hole 6. By doing this, the second squeegee 3-2 works to supply additional solder paste 4 to supplement the insufficient supply of solder paste 4 of the first squeegee 3-1, so that a sufficient and constant amount of solder paste 4 is supplied. Add amount of solder paste 4 to component mounting pattern 5
can be supplied above.

〔Effect of the invention〕

According to the present invention, it is possible to supply a sufficient amount of solder paste to the component mounting pattern of a printed circuit board using two squeegees arranged in parallel, and it is possible to eliminate chipping due to insufficient paste, especially for minute holes. I can do it.

[Brief explanation of drawings]

FIG. 1 is a sectional side view showing one embodiment of the present invention. Figure 2 is a schematic diagram showing the conventional solder paste supply method;
Fig. 3 is a side view showing a part of the conventional solder paste supply method in cross section, Fig. 4 is a plan view showing the state of applying the paste in the conventional method, and Fig. 5 shows the shape of the supplied paste in the non-inventive method. FIG.

Claims (1)

[Claims] By pressing and sweeping a squeegee with solder paste over the printing plate spaced apart from the printed circuit board, the printing plate is brought into close contact with the printed circuit board, and the solder paste is passed through the through-holes of the printing plate and applied to the printed circuit board. In the top feeding method, by sweeping two parallel squeegees, while the printing plate is in close contact with the printed circuit board, the solder paste is first applied to the through holes using a first squeegee. 1. A method for printing solder paste, which comprises supplying the solder paste to the same through-hole using a second squeegee.