What is the best way to remove OSP coatings.

Here are some options for removing OSP coatings from pads of the BGA substrates. * Leave the substrates in storage for 13-14 months. Shelf life of OSP coating is ~12 months, depending on the product. * Wash the substrates in your aqueous washer. Each past through the washer will take about ~15 percent of the coating, depending on the product. * Soak the substrates in IPA or other solvent recommended by the OSP supplier. IPA will take ~70 percent of the coating after a fairly quick zoush, depending on the product. * Use steam to age the substrate in simulated shelf life conditions. In 24-96 hours, a shelf life period of more than one year could be simulated. * Reflow OSP substrates to reflow conditions used for solder paste reflow. * Send the substrates to your fabricator and ask them to strip the OSP.

A silver nitrate test can be used to verify the presence and integrity of the OSP coating. Silver nitrate of a known normality (0.01-0.10N) is placed by dropper on the board and held for a given time [10-60 sec]. This is rinsed dried and inspected. A discolored or darkened appearance of the copper MAY indicate an insufficient coating.

reply »