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Method of removing impurities from plating liquid

An impurity, chemical tin plating technology, applied in liquid chemical plating, coating, electrolytic components, etc., to reduce the number of times and improve industrial production efficiency

Inactive Publication Date: 2015-06-17
ROHM & HAAS ELECTRONICS MATERIALS LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The inventors have solved this problem through diligent research

Method used

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  • Method of removing impurities from plating liquid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-5

[0060] Prepare the electroless plating solution using the following components:

[0061] · Tin fluoroborate (Sn 2+ ) 37g / L

[0062] ·Methanesulfonic acid 50g / L

[0063] · Hypophosphorous acid 30g / L

[0064] · Thiosulfate: 100g / L

[0065] ·Nonionic surfactants in Table 1: 50g / L

[0066] Table 1

[0067] Example

nonionic surfactant

1

polyoxyethylene octylphenol

2

polyoxyethylene alkylamine

3

polyoxyethylene cetyl ether

4

Polyoxyethylene β-naphthyl ether

5

Polyoxyethylene polyoxypropylene cetyl ether

[0068] 20 g / L copper powder was added to each of the above plating solutions and stirred and heated at 65° C. for 5 hours. When the replacement reaction of copper and tin is completed, the electroless tin plating solution is degraded due to the presence of copper ions. These simulated-degraded baths were kept at 65°C; 70 g / L of p-toluenesulfonic acid was added as an additive, and the baths w...

Embodiment 6

[0072] Use benzenesulfonic acid to replace the p-toluenesulfonic acid in embodiment 4; benzenesulfonic acid joins in this simulated deterioration liquid that contains copper ion as additive, keeps at 65 ℃ in the same manner as embodiment 4, then cools plating solution to 25°C. After the bath cools, a free species is produced in the bath. The resulting free species caused precipitation, and the supernatant was sampled and atomic absorption spectrometry was used to determine the concentration of copper in the bath. The measured copper concentration was 0.4 g / L.

Embodiment 7

[0074] The preparation method of the simulated degraded electroless tin plating solution containing copper ions is the same as that in Example 3. The above simulated degradation bath was cooled to 30°C. At this point no free material was produced. The simulated degradation bath was maintained at 30°C and 70 g / L p-toluenesulfonic acid was added. Immediately after the addition, free species were produced in the bath. The bath was passed through a filter (0.2 micron) to remove the free species, and the concentration of copper in the filtered bath was determined by atomic absorption spectroscopy. The measured copper concentration was 0.9 g / L.

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Abstract

Impurities are removed from tin plating liquids by adding additives containing aromatic organic sulfonic acids or salts thereof to the tin plating liquids containing nonionic surface active agents and thiourea or thiourea compounds and producing a precipitate by cooling.

Description

field of invention [0001] The invention relates to a method for removing impurities from a tin plating bath. More precisely, the present invention relates to a method of removing impurities from a tin plating solution by forming a precipitate of the impurities and then removing the impurities from the tin plating solution without using a special device. Background technique [0002] In recent years, electroless tin plating has been widely used as a method of plating printed circuit boards, circuit patterns, etc. in machine parts, flexible substrates, and electronic components. Electroless tin plating of these articles is often performed by displacing tin plating over copper or copper alloys. When tin displacement plating is performed on copper or copper alloy plating, the displaced copper becomes copper ions and dissolves in the plating solution; the copper ions accumulate as the plating process proceeds. These accumulated copper ions lead to unacceptable plating and degra...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C18/16
CPCC23C18/31C25D21/18
Inventor 羽切义幸
Owner ROHM & HAAS ELECTRONICS MATERIALS LLC