Dry film resist stripping issue from double treated copper surfaces

Q. Hi,
I'm having problems with stripping dry film photoresist from double treated copper surfaces. Does anyone have any thoughts on this.
Thanks,

A. don't think you've given us much to go on, Robin, but we'll see if someone else can read between the lines.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Ted is available for instant help
or longer-term assistance.
2007

Q. I just graduated; now I am working at a wafer bumping technology company. Recently, we have a product about copper pillar (plate copper+tin), before plate we PVD a layer of titanium+copper, then coat dryfilm on the surface and expose the plating area by another machine, then we plate copper and tin. After that, we strip the dryfilm with chemical (we buy finished chemical). If there is residue on the wafer surface it will lead to the product low yield. How may I reduce the residue? Can anyone help me? Thanks so much.