I am using COB on my DOUBLE SIDED PCB. lastly we used Eletrolytic Ni / Flash Gold Plating. Our Boards vias Failed the UL corrosion Test. we did some cross-section analysis and found 10.75 �m of Nickel and 0.022 um of Gold and as the Process is electrolytic phosphrous Contains was not Found ( which usually protect Nickel from oxidization) the Wire Bonding for COB used is Aluminum Wire. all though the COB was Fine in that test.
My Query is
1. Is there any Std for thickness of Eletrolytic Ni and Gold ? i can find only the E"less thickness no E"lytic ?
2. Since in Eletrolytic Process no Phosphurous is used is it possibility of corrosion or oxidization of plating Holes?
3. Since i am not sure what thikness of Gold to Specify i can't sure if i used Aluminum Wire it may corrode too due to Nickel Al oxidization
4. How Reliable is the Aluminum Wire Bonding in terms of Pull test and Corrosion test ? i have Gone thru various Post messages from this forum and hopeful to get answer from you expert users.......!