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Soldering tin paste

A lead-free solder paste, lead-free solder powder based technology, applied in welding media, welding equipment, welding/cutting media/materials, etc., can solve the problem that the solderability of Sn-Zn-based solder paste is not necessarily effective and increase manufacturing costs, etc.

Inactive Publication Date: 2003-06-11
SENJU METAL IND CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] However, as mentioned above, the coating used for solder powder greatly increases the manufacturing cost of solder paste
In addition, depending on the coating method or method, the oxidation of solder powder may be promoted during the coating operation, so coating is not necessarily effective for improving wettability or solderability of Sn-Zn based solder paste

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0051] Calculated by mass percentage, the composition of 88.5% is the spherical powder of the Sn-Zn base lead-free solder alloy of 8%Zn-3%Bi-Sn (remainder), and has the 11.5% rosin flux of composition shown in table 1 Mix uniformly to prepare the solder paste of Examples or Comparative Examples.

[0052] The solder paste was screen printed on the surface of copper lines on a typical glass epoxy printed circuit board and used for reflow testing in a reflow oven where preheating and main heating were performed in conjunction with The same conditions were carried out for conventional Sn-Pb based solder pastes in order to evaluate the formation and spreadability of the solder balls.

[0053] Flux components (numbers for each component

represents mass%)

Example number

Comparative Example No.

1

2

3

4

1

2

polymerized rosin

44

39

43

38

46

41

Diphenylguanidine HBr

2

2

2

...

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PUM

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Abstract

A lead-free solder paste comprises an Sn-Zn based lead-free solder powder mixed with a flux. The flux contains at least one aromatic hydroxycarboxylic acid selected from the group consisting of aromatic carboxylic acids having one hydroxyl group in a meta position (such as 3-hydroxy-2-methylbenzoic acid) and aromatic carboxylic acids having at least two hydroxyl groups (such as dihydroxynaphthoic acid or dihydroxybenzoic acid) in an amount of 0.1-10.0 mass %. The flux may further include 0.5-20 mass % of an aliphatic hydroxy carboxylic acid (such as hydroxyoleic acid).

Description

technical field [0001] The invention relates to a solder paste for soldering electronic equipment, in particular to a lead-free solder paste using Sn-Zn-based lead-free solder. Background technique [0002] Sn-Pb based alloys have been used as solders since ancient times. The advantage of Sn-Pb alloy is that it has a low melting point and has good solderability. For example, Sn63%-Pb37% alloy, which is a eutectic composition and is the most typical solder, has a melting point of 183°C and can be soldered at a temperature of 200-230°C. [0003] This eutectic Sn-Pb solder was commonly used in soldering of electronic devices in the past. Recently, surface mount technology (SMT) is widely used to mount electronic components in printed circuit boards because this technology allows size reduction, high density, high performance, and low cost. [0004] In SMT, solder paste (also called solder paste) is used, which contains solder powder uniformly mixed with solder flux, especial...

Claims

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Application Information

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IPC IPC(8): B23K35/363B23K35/02B23K35/26B23K35/36C22C13/00H05K3/34
CPCH05K3/3484B23K35/262B23K35/025B23K35/3618H05K3/3485
Inventor 田口稔孙高浦邦仁平田昌彦吉田久彦长嵨贵志
Owner SENJU METAL IND CO LTD
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