A secondary image transfer (SIT) or secondary image resist is used to produce printed circuit boards with two different surface finishes. By selective protection of a board it is e.g. possible to selectively apply a Nickel/Gold Surface Finish to e.g. contact pads of mobile phones and an OSP Surface Finish on the assembly pad's.

Secondary Image Transfer Products

The AUROSIT® 2149 series are optimized plating resists for the selective plating of electroless Nickel/Gold (ENiG) or electrolytic Nickel/Gold surface finish. They have a high chemical resistance in these processes as well as an optimized leach out behavior, thus they do not show any influence on the lifetime or the performance of the plating processes used. AUROSIT 2149 HS is the standard product, which now was complemented by AUROSIT 2149 F a version with higher flexibility.

Secondary Image Transfer Features and Benefits

• Application by screen-printing down to about 150 microns resolution
• Excellent adhesion on copper, solder mask and covercoats
• Protection of PCB's during various finishing processes
• Stable in common Ni/Au plating baths (e.g. Aurotech)
• Easily and completely strippable with caustic (NaOH)
• Cost-efficient and reliable process

Secondary Image Transfer for Enig / Immersion Gold plating, manufactured by Lackwerke Peters, distributed and serviced in Asia by Atotech.