Continuously self-catalyzed deposition chemical plating solution of tin and using method thereof

An electroless plating solution and self-catalysis technology, applied in the field of electroless plating, can solve the problems of inability to realize continuous self-catalytic deposition of tin, low deposition rate of electroless tin plating, failure to obtain industrial application, etc., and achieve high batch production stability, The effect of fast deposition rate and porosity reduction

Inactive Publication Date: 2011-11-09
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the high hydrogen evolution potential and low catalytic activity of tin, if formaldehyde, sodium hypophosphite, borohydride and other reducing agents are used alone, continuous self-catalytic deposition of tin cannot be achieved, and thick coatings cannot be obtained.
With a strong reducing agent, such as Ti 3+ , V 2+ , Cr 2+ Electroless tin plating has not been applied industrially due to low deposition rate, poor stability, unsatisfactory repeatability, high price

Method used

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  • Continuously self-catalyzed deposition chemical plating solution of tin and using method thereof
  • Continuously self-catalyzed deposition chemical plating solution of tin and using method thereof
  • Continuously self-catalyzed deposition chemical plating solution of tin and using method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] The formula of electroless tin plating solution is:

[0026]

[0027] The process conditions of the electroless tin plating solution are: the temperature of the plating solution is 88±2°C, the pH value is 2.0, the electroless plating time is 3 hours, and the loading capacity of the plating solution is 1.2dm 2 / L.

[0028] The thickness of the electroless coating obtained in Example 1 is 31.4 μm, the appearance is silver-white-semi-bright, the tin content is 95.8wt%, and the porosity is lower than 4 pieces / 6cm 2 . In a tin-lead alloy in which the flux is 25% rosin isopropanol and the solder is 60% tin + 40% lead, the wetting time is less than 2s, and the solderability is good. After passivation treatment, the appearance and color of the coating will not change after being placed in the air for 3 months. The passivation process is: K 2 Cr 2 o 7 2H 2 O: 15g / L, KOH: 5-8g / L, (NH 4 ) 6 Mo 7 o 24 4H 2 O: 15~18g / L, T: room temperature, time: 10~15min.

Embodiment 2

[0030] The formula of electroless tin plating solution is:

[0031]

[0032] The process conditions of the electroless tin plating solution are: the temperature of the plating solution is 88±2°C, the pH value is 1.5, the electroless plating time is 3 hours, and the loading capacity of the plating solution is 1.2dm 2 / L.

[0033] The thickness of the electroless coating obtained in Example 2 is 25.5 μm, the appearance is silver-white-semi-bright, the tin content is 93.6wt%, and the porosity is lower than 4 pieces / 6cm 2 . In a tin-lead alloy in which the flux is 25% rosin isopropanol and the solder is 60% tin + 40% lead, the wetting time is less than 2s, and the solderability is good. After passivation treatment, the appearance and color of the coating remain unchanged after being placed in the air for 3 months.

Embodiment 3

[0035] The formula of electroless tin plating solution is:

[0036]

[0037]

[0038] The process conditions of the electroless tin plating solution are: the temperature of the plating solution is 88±2°C, the pH value is 1.0, the electroless plating time is 3 hours, and the loading capacity of the plating solution is 1.2dm 2 / L.

[0039] The thickness of the electroless coating obtained in Example 3 is 21.2 μm, the appearance is silvery white, the tin content is 92.8wt%, and the porosity is lower than 4 pieces / 6cm 2 . In a tin-lead alloy in which the flux is 25% rosin isopropanol and the solder is 60% tin + 40% lead, the wetting time is less than 2s, and the solderability is good. After passivation treatment, after 3 months in the air, the appearance and color of the electroless tin plating layer have no change.

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Abstract

The invention discloses continuously self-catalyzed deposition chemical plating solution of tin and a using method thereof. Half-bright and silvery-white tin-copper alloy deposition layers are obtained on pure copper and a copper alloy substrate. In the chemical plating solution, stannous chloride serves as a main salt, thiourea serves as a main complexing agent, trisodium citrate serves as an auxiliary complexing agent, sodium hypophosphite serves as a reducing agent, disodium ethylene diamine tetraacetate serves as an antioxidant, a hydrochloric acid serves as a stabilizing agent, gelatin serves as a leveling agent and benzaldehyde serves as an auxiliary brightening agent. The using method comprises the following operating conditions that: the pH value of the plating solution is 0.8 to 2.0; the temperature is 80 to 90 DEG C; the loading capacity is 0.8 to 1.5 dm2 / L; and the mechanical stirring speed is 50 to 100 rpm. The continuously self-catalyzed deposition chemical plating solution of the tin and the using method thereof have the advantages of capability of obtaining half-bright and silvery-while tin-copper alloy clad layers with different thicknesses by controlling chemical plating time, high deposition rate, remarkable grain refinement, improvement on surface evenness of the clad layer and batch production stability, secure interface combination, strong change resistance of the clad layer after being passivated, and broad application prospect in the products of deep hole elements, blind hole elements, difficult-to-handle miniature electronic components and parts, printed circuit boards PCBs and the like.

Description

technical field [0001] The invention relates to the technical field of chemical plating, in particular to the continuous self-catalyzed deposition chemical tin plating technology of tin. Background technique [0002] Tin coating is a coating with good solderability and certain corrosion resistance, which is widely used in electronic components and printed circuit boards. At the same time, tin is stable to organic acids and tin compounds are harmless to the human body, and are also widely used in the food industry. The tin coating can be prepared by electroplating, immersion plating and electroless plating. Immersion tin plating is easy to operate and low in cost, but the thickness of the coating is limited, generally only 0.5 μm, and the plating solution is easily poisoned, which cannot meet industrial requirements. Electrolytic tin plating cannot process deep-hole parts, blind-hole parts and small electronic components that are difficult to handle; the electroless tin pla...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23C18/52
Inventor 徐瑞东王军丽
Owner KUNMING UNIV OF SCI & TECH
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