On Tuesday 23 August 2005 01:34 am, Dave wrote: > Once you mix up a liter of this stuff, how > long can you keep it before it goes bad? > How many times can you dip circuit boards > in it before the solution is exhausted? The length of time you can keep the solution is dependent on a couple of variables. Specifically, Ultra violet light and air are the primary sources of deterioration. Be sure to store the solution in an air tight container that is tented brown (Something like a container used to store photographic chemicals that are sensitive to light). Also, do not use a rubber stopper because natural latex and synthetic rubber will react with the solution - Use a plastic screw-on cap. When using the solution, try and pour out only what you need to submerse the board(s). If you have solution that you have used to plate boards that is still active, NEVER put it back into the bottle with the fresh solution - Store used solution in another UV blocking bottle. Also, be sure to mix the solution with distilled water. The minerals in tap water will affect the ability of the solution to plate evenly and adversely affect the life of the solution. Solution that you have used is reliable for a couple of days. Solution that have mixed up and not used will be reliable for at least one month. The more air and UV light you are able to keep out of the solution, the longer it will last. I've had solution last for 3 months. Wash and dry the bottles your going to store the solution in mild soap and water and then rinse 3 times with distilled water. Cleanlyness equates to quality plating and long lasting solution. As you plate boards, you going to notice a coagulation that forms. This is normal. The coagulation is the thiourea forming a complex with the copper which in turn protects the tin alloy plating process (The copper cannot replate back onto boards). Typically, it takes somewhere between 5 and 20 minutes to plate a board, depending on the size of the board and the amount of copper area to be plated. A small board will obviously plate faster than a large board. One liter (1000ml) of solution will plate around 20 to 25 square feet of copper. The plus or minus 5 feet is proportional to board hygiene (Clean boards, predip or no predip) and the condition of the solution (Quality of the chemicals and storage conditions). Stellar results will be obtained by keeping your solution clean, good PCB hygiene and using a predip. Once you use this method, everything else will appear second rate. Good luck! Please post your results back to the list! Regards Marvin > I think I can borrow a chemistry lab to make this stuff.
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