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Solder Paste

a technology of solder paste and paste, which is applied in the direction of welding/cutting media/materials, manufacturing tools, and soldering apparatus, etc., can solve the problems of failure to cover the supply of solder and the insufficient amount of filling solder, so as to suppress the variation in the height of the solder bump, maintain a certain amount of print, and suppress the missing bump

Inactive Publication Date: 2014-05-15
SENJU METAL IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The solder paste described in this patent has a unique viscosity that allows it to be filled in small apertures without needing pressure. This results in a more consistent height of solder bumps and prevents bumps from being missing. Additionally, even in small printing apertures, the solder paste can be sure to have a good print amount.

Problems solved by technology

If any faults occur in supplying the solder paste, these faults in supplying it cannot be covered even when the following component mounting step and the following soldering step by heating are performed under best conditions.
This fails in filling an inadequate amount of solder.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

Composition Example of Solder Paste according to the Embodiment

[0060]Solder paste according to the embodiment is printed on a substrate by a screen method using a screen as mask member or a film method using a film as the mask member. In the solder paste according to the embodiment, the printing by the screen method or the film method is performed under a predetermined decompression condition, in this embodiment, vacuum condition.

[0061]The solder paste according to the embodiment is produced so that the flux containing solvent having a constituent such that volatilization thereof is suppressible under vacuum condition is mixed with solder powders. Further, the solder paste according to this embodiment has a viscosity so that it is pushed into the apertures in the screen or the film by pressure force of a squeegee and it is pushed into the apertures under atmospheric pressure when it is opened from the vacuum condition to the atmospheric pressure.

[0062]A degree of volatilization of a...

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Abstract

To provide solder paste that can be filled in minute apertures.The solder paste that is printed on a substrate through a mask member in which apertures are formed is supplied to the apertures of the mask member under decompression pressure and has a viscosity so that the solder paste is filled in the apertures under atmospheric pressure. It is preferable that the solder paste has a viscosity of 50 through 150 Pa·s and a thixotropic ratio of 0.3 through 0.5. Further, the solder paste is obtained by mixing a flux containing solvent having a boiling point such that volatilization thereof is suppressed under the decompression pressure and solder powders. It is preferable that in the flux, the solvent having the boiling point of 240° C. or more is used and the solvent is octanediol.

Description

TECHNICAL FIELD[0001]The present invention relates to solder paste obtained by mixing a flux with solder powders and it particularly relates to solder paste that can be filled in minute apertures to form solder bumps.BACKGROUND[0002]A first step in SMT process that is used for assembling an electronic substrate starts from supplying on the substrate an appropriate quantity of the solder paste formed by mixing a flux with solder powders. There is a method referred to as a screen printing one of the methods of supplying the solder paste on the substrate.[0003]FIGS. 10A, 10B, 10C, 10D, 10E and 10F are motion illustration diagrams showing an example of a conventional screen printing. In the screen printing, as shown in FIG. 10A, a screen 104 made of a steel plate in which apertures 103 are formed with them being aligned with electrodes 102 of a substrate 101 and the substrate 101 are closely contacted to each other, as shown in FIG. 10B.[0004]The solder paste S is put on the screen 104,...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B23K35/02
CPCB23K35/025B23K1/0016B23K3/0638B23K3/082B23K35/3612B23K35/362B41M1/12B41M1/26B23K2101/42H05K3/1233H05K2203/085H05K3/3485B23K35/0244B23K35/262B23K35/3613C22C13/00B23K3/06B23K35/22H05K3/34H05K3/04H05K3/4007H05K2203/0139
Inventor OKADA, SAKIE
Owner SENJU METAL IND CO LTD