Process flow of PCB multilayer board

1 Process flow

The printed circuit board with the prepared graphics → acid degreasing → scanning water washing → secondary countercurrent water washing → micro-etching → scanning water washing → secondary countercurrent water washing → copper plating predip → copper plating → scanning water washing → tin plating predip → Tin plating → secondary countercurrent washing → lower plate

2 detailed process

2.1 Tin Plating Prepreg

2.1.1 Composition and operating conditions of tin-plating pre-dip

2.1.2 The method of opening the tin prepreg tank 4

First add half a cylinder of distilled water, then slowly immerse and add 15L sulfuric acid with a mass fraction of 98 percent , stir and cool, add 1.5L Sulfotech Part A, stir evenly, add distilled water to 300L, stir evenly, and it is ready to use.

2.1.3 Maintenance and control of tin-plating pre-soak bath

Add 1L sulfuric acid and 100mL Sulfotech Part A for each 100m2 board. Replace the bath every time the bath has processed 1500m2 of plates.

2.2 Tin plating

2.2.1 Composition and operating conditions of tin plating solution 5

2.2.2 The method of opening the tinning tank 2

First add half a cylinder of distilled water, then slowly add 98L sulfuric acid with a mass fraction of 98 percent , after stirring and cooling, add 40kg Tin Salt 235 to cool to 25 degree , add 76 L Sulfotech Part A, 15.2 L Solfotech Part B, 30.4 LSTHAdditive Sulfolyt, Add distilled water to the liquid level and circulate (electrolyze 2AH/L at 1.5A/dm2).

2.2.3 Maintenance and control of tin plating bath liquid

Analyze tin and sulfuric acid before work. 11L sulfuric acid, 600 g Tin Salt 235, 600 mL Sulfotech Part A, 800 mL Sulfotech Part B, 750 mL STH Additive Sulfolyt should be added for each 100m2 plate. The automatic addition system added 56mL of Sulfotech Part A at 200AH.

The solution must be subjected to the Hull cell test every week to observe and adjust Sulfotech Part A and Sulfotech Part B.

Item Scope Best Value

Sn2 plus 20-30 mL/L 24 mL/L

W(H2SO4) is 98 percent 160-185mL/L 175mL/L

Sulfotech Part A (Sulfotech Part A) 30-60mL/L 40mL/L

STH(STH Additive Sulfolyt) 30-80mL/L 40mL/L

Sulfotech Part B 15-25mL/L 20mL/L

Operating temperature 18-25 degree 22 degree

Cathode current density 1.3-2.ASD 1.7ASD 2