Summary for backside wafer plating Discussion
Backside of wafers plating can happen in electroless nickel because EN does not require conductivity; it will deposit on any surface that has been properly activated and is plateable, as James Watts and Guillermo Marrufo explain. The original question asked why a wafer with a dielectric backside was still getting nickel on the back. Watts said the practical fix is to find a masking method compatible with the plating process, noting that some masks are difficult to remove completely and may require repeated solvent cleaning. He also suggested getting help from the plating vendor’s technical service or another industry source familiar with the process. Marrufo added that electroless nickel can even deposit on nonconductive materials such as plastic tank walls or glass beakers, so the backside may need to be masked before processing.
Q. My wafers are getting backside plating which are not supposed to, I am doing electroless Nickel plating. Backside of the wafer is dielectric. Any insight on this issue will be greatly helpful. What are the reasons behind plating the backside of the wafer?
Satish Yeldandi
– Boise, Idaho, United States
December 16, 2011
EN will plate anything that is properly activated and plateable. You have to find a way to mask off the back side that is compatible with the plating process. Unfortunately, some masks are nearly impossible to get off COMPLETELY without numerous clean solvent dips.
Find someone in the industry that can point you in the right direction. I would start with tech services of the OEM if your EN vendor cannot help you. They want your business, so most, at least the good ones, will do a lot to help you.
James Watts
– Navarre, Florida
First of two simultaneous responses — December 21, 2011
Electroless indeed means the surface doesn’t need to be conductive, only receptive or “active”. It is not infrequent to see nickel deposits on plastic tank walls or glass beakers [beakers on
eBay
or
Amazon [affil link] . You may need to mask those surfaces before processing,
G. Marrufo
Guillermo Marrufo
– Monterrey, Mexico
Second of two simultaneous responses — December 21, 2011