Why it is sometimes necessary to re-seat a board or chip

From: cclist at sydex.com On 30 Dec 2008 at 22:41, dwight elvey wrote: Not really that hard, depending on the alloy. For instance, I can plate brass in my own shop--it's not difficult; just an acid bath process. (Tin-lead) Solder has been electroplated onto PCBs for decades. Some people have pointed to their college chemistry texts and told me definitively that it was impossible to electrodeposit an alloy. I don't know where that one got started. I'll agree that cooking up a plating bath can be a black art. Stuff you'd never think would affect the outcome such as sugar sometimes winds up in them and I know a retired fellow who ran a plating shop who swore that he got better results than anyone else because he urinated in his tanks. From: http://www.pfonline.com/articles/pfd0022.html Hard, Bright Gold Platers who gold plate contacts and connectors generally use bright acid gold formulations. These baths contain complexed cobalt or nickel in small quantities, to improve hardness and brightness of the deposit. Such gold electroplates will be 99.7 to 99.9 pct pure, and hardness can be 120 to 300 Knoop. The small amount of nickel or cobalt will interfere with die bonding, so these baths cannot be used for semiconductor plating. Hard, bright gold baths, if operated with good housekeeping and chemical control, have very long life-often three years and more. Cheers, Chuck