Lead-free soldering tin spraying process capable of making tin thickness uniform

A lead-free solder, uniform thickness technology, used in welding media, manufacturing tools, metal processing, etc., can solve problems such as solder rejection, IMC exposure, tin shrinkage, etc.

Inactive Publication Date: 2020-09-25
DONGGUAN SIGMA TIN ALLOY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Tin spraying is a step and process in the production process of PCB boards. Specifically, the PCB board is immersed in a molten solder furnace, so that all exposed copper surfaces will be covered with solder, and then passed through the hot air knife pressure. Remove the excess solder on the PCB board, because the tin layer on the surface of the PCB board after tin spraying is similar to the solder paste, so the welding strength an

Method used

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  • Lead-free soldering tin spraying process capable of making tin thickness uniform
  • Lead-free soldering tin spraying process capable of making tin thickness uniform
  • Lead-free soldering tin spraying process capable of making tin thickness uniform

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0076] A uniform-thickness lead-free soldering process, the steps at least include:

[0077] (1) Pre-treatment of tin spraying: micro-etch cleaning, water washing, drying, and coating of flux on the PCB board in sequence;

[0078] (2) Tin spraying machine: perform solder alloy tin spraying on the PCB board processed in step (1);

[0079] (3) Post-spray tin treatment: The PCB boards treated in step (2) are washed in hot water, washed with water, and dried in sequence.

[0080] The mass ratio of the flux to the solder alloy is 1:95.

[0081]The solution for microetching cleaning in step (1) is sulfuric acid and persulfate; the concentration of the sulfuric acid is 5.5±0.5wt%; the concentration of the persulfate is 100±5g / L. The persulfate is sodium persulfate.

[0082] The temperature of microetching cleaning in step (1) is 39±1° C.; the speed of microetching cleaning is 3±0.5 m / min.

[0083] The water washing described in the step (1) is flowing water washing, which is chan...

Embodiment 2

[0100] A uniform-thickness lead-free soldering process, the steps at least include:

[0101] (1) Pre-treatment of tin spraying: micro-etch cleaning, water washing, drying, and coating of flux on the PCB board in sequence;

[0102] (2) Tin spraying machine: perform solder alloy tin spraying on the PCB board processed in step (1);

[0103] (3) Post-spray tin treatment: The PCB boards treated in step (2) are washed in hot water, washed with water, and dried in sequence.

[0104] The mass ratio of the flux to the solder alloy is 1:93.

[0105] The solution for microetching cleaning in step (1) is sulfuric acid and persulfate; the concentration of the sulfuric acid is 3±0.5wt%; the concentration of the persulfate is 80±5g / L. The persulfate is sodium persulfate.

[0106] The temperature of microetching cleaning in step (1) is 30±1° C.; the speed of microetching cleaning is 2±0.5 m / min.

[0107] The water washing described in the step (1) is flowing water washing, which is change...

Embodiment 3

[0124] A uniform-thickness lead-free soldering process, the steps at least include:

[0125] (1) Pre-treatment of tin spraying: micro-etch cleaning, water washing, drying, and coating of flux on the PCB board in sequence;

[0126] (2) Tin spraying machine: perform solder alloy tin spraying on the PCB board processed in step (1);

[0127] (3) Post-spray tin treatment: The PCB boards treated in step (2) are washed in hot water, washed with water, and dried in sequence.

[0128] The mass ratio of the flux to the solder alloy is 1:98.

[0129] The solution for microetching cleaning in step (1) is sulfuric acid and persulfate; the concentration of the sulfuric acid is 8±0.5wt%; the concentration of the persulfate is 150±5g / L. The persulfate is sodium persulfate.

[0130] The temperature of microetching cleaning in step (1) is 40±1° C.; the speed of microetching cleaning is 4±0.5 m / min.

[0131] The water washing described in the step (1) is flowing water washing, which is chang...

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Abstract

The invention relates to the technical field of tin soldering processes, and provides a lead-free soldering tin spraying process capable of making the tin thickness uniform. The process at least comprises the following steps: (1) tin spraying pretreatment is conducted, wherein a PCB sequentially is subjected to micro-etching cleaning, water washing, blow-drying and soldering flux coating; (2) tinspraying is conducted through a tin spraying machine, wherein soldering tin alloy is sprayed on the PCB treated in the step (1), and the temperature of a tin furnace is 265-275 DEG C; and (3) tin spraying post-treatment is conducted, wherein the PCB treated in step (2) sequentially subjected to soaking, hot water washing, water washing, and drying treatment.

Description

technical field [0001] This field relates to the technical field of soldering process, and more specifically relates to a uniform-thickness lead-free soldering process. Background technique [0002] Tin spraying is a step and process in the production process of PCB boards. Specifically, the PCB board is immersed in a molten solder furnace, so that all exposed copper surfaces will be covered with solder, and then passed through the pressure of the hot air knife. Remove the excess solder on the PCB, because the tin layer on the surface of the PCB after spraying tin is similar to the solder paste, so the welding strength and reliability are better, but due to its processing characteristics, the surface flatness of the sprayed tin Not good, especially for small electronic components with packaging types such as BGA. Due to the small soldering area, if the tin thickness is uneven, it may cause problems such as shrinkage of tin, solder rejection, and IMC exposure. Therefore, a pr...

Claims

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Application Information

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IPC IPC(8): B23K1/00B23K1/20B23K35/26B23K35/363B23K101/42
CPCB23K1/00B23K1/203B23K1/206B23K35/262B23K35/3612B23K35/362B23K2101/42
Inventor 杜老乙
Owner DONGGUAN SIGMA TIN ALLOY CO LTD
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