Lead-free tin green green printed circuit board production process

SL-2 Multi-Copper Surface Anti-Oxidation and Anti-Corrosion Agent

SL-2 multifunctional copper surface oxidation and corrosion inhibitor is a new high-tech environmental protection product. It can form a dense organic film on the surface of metallic copper when it is in contact with it. As a result, it plays an anti-oxidation and anti-corrosion effect on the surface of metallic copper.

The product can be widely used in the whole process of printed circuit board production. For example, during the process of oxidation prevention, the tin-lead-dissolved tin mixed with nitric acid can achieve the best protection for metallic copper while dissolving the lead-tin coating, and can also be used as the antioxidant layer of the final product instead of through the hot air leveling treatment. Solder oxide layer.

Another very important application of this product is to replace the current use of lead-platinum plating process to achieve circuit board production without lead, tin waste discharge.

application:
*Instead of lead-platinum plating Processes for use are: ... electroplating copper - washing - dipping SL-2 (greater than 2 minutes) - hot water - drying - faded film - alkaline etching...
* End product anti-oxidation treatment (instead of hot air leveling)
The use process is: ... Washing - dipping SL-2 (10 seconds) - hot water - drying ...

* Anti-oxidant and anti-corrosion additives for copper surface Add it to acid copper plating solution, acidic lead-lead tin solution, and acidic cleaning solution according to the specific use conditions, which can effectively alleviate the oxidation and corrosion caused by acidic liquids on copper. After the treated copper surface is washed with water, it can keep the copper surface from being oxidized for a long time (it is recommended to add 10%, the user can adjust according to the use conditions).

Product technical indicators:
Appearance: Blue-green transparent or translucent liquid Specific gravity: 1.00
PH value: 4.45-4.50

Mechanism Introduction:
SL-2 Multi-Copper Anti-oxidant Anti-corrosion agent contains an organic compound. The compound has 1 active group. This group can form a covalent bond with copper. As a result, the molecules are tightly linked to copper and do not bond to other organic materials or lead-tin metals. In this way, when the SL-2 multifunctional copper surface oxidation and corrosion inhibitor is in contact with copper, it will only form a dense organic film on the copper surface. This compound has solubility in acidic aqueous solutions, is insoluble in neutral and alkaline aqueous solutions, and assumes a molten state when the ambient temperature exceeds 100°C. The SL-2 multifunctional copper surface oxidation and corrosion resisting agent utilizes these chemical properties to achieve effective protection of copper under alkaline conditions, faded organic films, and etching; copper surface protection in the air Oxidation; In high temperature soldering, the solder can penetrate the anti-oxidation film; Under acidic conditions, the anti-oxidation anti-corrosion film is removed.

Use examples:
After electroplating of copper in place of the electroplated lead-tin process line, the plates were immersed in a pre-impregnated solution (pre-impregnated solution containing 5% SL-2 in 5% aqueous hydrochloric acid; operating conditions: room temperature, time to ensure surface and hole wall The time to fully infiltrate. If the oxidation of the board surface is severe, the infiltration time can be properly extended; flush the surface of the board with water to ensure that the liquid adhering to the board surface is not acidic; Immerse the board in the SL-2 multi-purpose copper surface to prevent oxidation. Corrosion agent, the infiltration time at 20-25 °C for 2 minutes (when the solution temperature is lower, the infiltration time can be properly extended. The maximum infiltration temperature should not exceed 40 °C); the plate in 70-80 °C hot water Soaking, soaking time to ensure that the board surface and the hole wall with full contact with hot water, usually 10-20 seconds; the board is fixed on the shelf, into the oven (the oven should be in a ventilated state), 140 °C, 10 minutes. When the panel temperature is close to room temperature, the developing film is faded out in a 5% aqueous alkali solution, and you can clearly see that the copper surface of the positive image part is significantly different from the copper of other parts; Etching in an alkaline copper chloride etching solution etches copper in the negative pattern portion. This step is to ensure that there are no solid particles in the etchant, and the transfer wheel of the etching machine is preferably round. If soaked swing etching is used, the effect is best; after etching, the plate can be rinsed with clean water to perform subsequent processes.

Example I. Anti-oxidation treatment between processes After the holes are electroplated with copper, the plates are placed in the prepreg described in Example 1. The operating conditions are: room temperature, time to ensure that the surface of the plate and the walls of the holes can fully infiltrate (generally 10 Seconds); Rinse the plate with water to ensure that the liquid attached to the plate is not acidic; Place the plate on a rack to air dry naturally (or other drying methods) to keep the copper surface bright for several days; dilute pickling After washing, the subsequent steps can be performed.

Example 2: Anti-oxidation treatment of the final product After printing (coating) of solder resist and printed characters, the board was degreasing, and the board was placed in the pre-dip liquid described in Example 1, operating conditions: room temperature, time In order to ensure that the surface of the board and the hole can be fully infiltrated, remove the time of the oxide layer; flush the surface with water to ensure that the liquid attached to the board surface is not acidic; after cleaning with pure water again, immerse the board in the SL-2 The infiltration time of the functional copper surface anti-oxidation and anti-corrosion agent is 10 seconds at room temperature; the plate is soaked in hot water at 70-80° C. soaking time to ensure that the surface of the plate and the hole wall are in full contact with the hot water, generally For 10-20 seconds; after rinsing with clean water, the plate is dried, and the drying conditions are: 120° C., 10 minutes; then, after the appearance and inspection of the cutting, the product is finished.

Example 3: As a Corrosion Inhibitor Additive for Sn/Pb SnO2 Addition of SL-2 multi-functional copper anti-oxidation and anti-corrosion agent to the nitric acid aqueous solution can effectively protect the copper during the process of removing lead and tin. It is recommended to add 10%, users can adjust within the range of 1-20% according to the actual situation. If lead and tin fade slowly, you can reduce it.

Example 4: After electroplating of copper in place of electroplated lead-tin process lines, the plates were immersed in a pre-impregnated solution (the pre-infusion solution was 5% SL-2 in a 5% aqueous solution of hydrochloric acid; the operating conditions were: room temperature, and the time was to ensure the plate surface. And the time that the hole wall can fully infiltrate. If the oxidation of the board surface is serious, the infiltration time can be prolonged.) Flush the board surface with water to ensure that the liquid attached to the board surface is not acidic; Immerse the board into the surface of the SL-2 multifunction copper. Anti-oxidant and anti-corrosion agent, infiltration time at 20-25 °C for 2 minutes (when the temperature of the solution is lower, the infiltration time can be properly extended. The maximum infiltration temperature should not exceed 40 °C); the plate in 70-80 °C Soak in hot water, soaking time to ensure that the surface of the board and hole wall and hot water full contact, usually 10-20 seconds; the board is fixed on the shelf, into the oven (the oven should be in a ventilated state), 140°C, 10 minutes. When the panel temperature is close to room temperature, the developing film is faded out in a 5% aqueous alkali solution, and you can clearly see that the copper surface of the positive image part is significantly different from the copper of other parts; Etching in an alkaline copper chloride etching solution etches copper in the negative pattern portion. This step is to ensure that there are no solid particles in the etchant, and the transfer wheel of the etching machine is preferably round. If soaked swing etching is used, the effect is best; after etching, the plate can be rinsed with clean water to perform subsequent processes.