JPS63203277A - Printed board for creamy solder - Google Patents

Abstract

PURPOSE:To secure the creamy solder for each part in proper amt. and to effect a reflow soldering of high reliability by forming a thinner plate thickness part by half-etching, printing a creamy solder by a flat squeegee and changing the plate thickness of a creamy solder printing board at the necessary part only. CONSTITUTION:The plate thickness of one part of a printing board 7 is thinned by half-etching to form a thin plate thickness part 4. As a result, the printing state becomes t1 at the part for plate thickness T1 and t2 at the part for plate thickness T2, so the plane area is not required to be reduced forcibly. No print- omission defective of the creamy solder is therefore caused, the height t2 is low at the fine pitch side and the deformation at preheating and reflowing times is reduced and the setting of the creamy solder amt. can easily be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printing plate for cream solder used in printing electronic parts and the like onto circuit boards with cream solder using a solder reflow method.

BACKGROUND OF THE INVENTION FIG. 3 is a side view showing printed cream solder and lands of a circuit board to which electrodes of a conventional electronic component are bonded.

FIG. 4 is a plan view and a sectional view showing an example of a conventional cream solder printing plate. FIG. 5 shows an electronic component and soldering after reflow. FIG. 5(a) shows a chip component, and FIG. 5(b) shows a GULL-WING type flush flat package IC. Next, a conventional example of a cream solder printing plate will be explained with reference to the drawings. The amount of solder (fillet) 15.16 after the glue flow in FIG. 5 is ensured by the shape of the mask 1.2 of the printing plate 12. The amount of solder 15 and 16 depends on the shape (aXb) and plate thickness of cream solder 8 in Figure 3, but from the viewpoint of quality bridging during reflow, generation of solder balls, and plate removal when printing cream solder, there are defects. , a is A >
a > 0.25 w, b is B > b > 0.25 m
Then decide on the plate thickness. Note that 11 is a square squeegee.

Problems to be Solved by the Invention However, electronic components have become extremely miniaturized.
When the size of (C1 in Fig. 3 becomes the same, and when printing and reflowing chip parts or electrodes with an electrode spacing of 0.8 m or more on the same board, the mask 1.2 in Fig. 4 becomes smaller ( a < 0.25 condition), the cream solder does not come through the plate well, and the plate is clogged with cream solder, resulting in mask 1 in Figure 4.
．． If 2 is set to 0.25■ or more, small flat package ICs will cause bridging, and conversely, if the thickness of the printing plate is made thinner, there will be a shortage of solder for other flat package ICs and chip components, resulting in highly reliable solder. It has become difficult to join.

The present invention solves the above-mentioned problem, and when mounting various parts of different shapes on the same board, it is possible to apply the optimum amount of cream solder to each part on the printed circuit board. The purpose is to provide a printing plate for Yuwata cream solder.

Means for Solving the Problems The present invention eliminates the drawbacks of the above-mentioned conventional examples.
When mounting small items or chip components, the thickness of the cream solder printing plate is partially changed to ensure an appropriate amount of cream solder for each component, allowing highly reliable flow soldering.

Therefore, according to the present invention, by partially changing the thickness of the mask of the solder printing plate, it is possible to secure the amount of solder on the land of each electronic component within the same board, which cannot be adjusted by the mask area, and the reliability is improved. This has the effect of allowing high reflow soldering.

Embodiment FIG. 1 is a plan view of a printing plate for cream solder showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view thereof and a cross-sectional view of the printed state. In FIGS. 1 and 2, 7 is a printing plate, and 1, 2, and 3 are masks for printing and supplying cream solder. 4 is a part where the printing plate 7 is partially thinned by half-etching, and the planar area of the mask (a in Fig. 3) is
The amount of solder that cannot be adjusted with xb) is adjusted by the thickness of the plate. Then, instead of using the conventionally used square squeegee (11 in Figure 4), a flat squeegee 5 or a sword squeegee that can follow the steps T and -T2 in Figure 2 is used to slide it on the printing plate 7. Cream solder 6 is printed on a printed circuit board through a mask. In this way, in the above embodiment, since the plate is made thinner with the thinner plate thickness section 4, the printing condition is t for the plate thickness T1 in FIG. 2, and t2 for the plate thickness T2. , since there is no need to reduce the plane area (aXb in Figure 3), printing of cream solder does not cause defects, and the height t2 on the narrow pitch side is low, so the shape does not collapse during preheating and reflowing. This has the advantage that the amount of cream solder can be easily set because the amount of cream solder is small.

Effects of the Invention As is clear from the above embodiments, the present invention forms a thin plate thickness part by notch etching, prints cream solder with a flat squeegee, and changes the plate thickness of the cream solder printing plate only in necessary parts. This makes it easy to secure the amount of solder when soldering electronic parts, and the cream solder removal during printing has the effect of preventing defects, bridging during flow, and insufficient solder.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a printing board for cream solder according to an embodiment of the present invention, FIG. 2 is a sectional view of this embodiment, FIG. 3 is a side view of a conventional printed circuit board for cream solder, and FIG. A plan view and a sectional view of the conventional example, and FIG. 5 is a side view after the conventional glue flow. 1...Mask for flat package IC, 2...Mask for chip components, 3...Fine pitch flat (mask for cage IC, 4...Cream solder printing plate)...
- Fetching part, 5... Flat squeegee, 6... Cream solder, 7... Cream solder printing board, 8... Printed cream solder, 9... Printed board electrode land,
10... Printed circuit board frost; polar land. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure /~J,・? S2: T, % dollar 21 units 0 units Fig. 2 Fig. 3 (in (Ron Fig. 4 □ Fig. 5

Claims (1)

[Claims] The printing plate that supplies the cream solder is half-etched to make it thinner, and the cream solder is printed on the printed circuit board by sliding it on the printing plate using either a flat squeegee or a sword squeegee. Printing board for cream solder.