Temperature stress during lead-free soldering processes can cause a yellowing of the solder resists and marking inks. Elpemer SD 2491 SM-TSW is yellowing-stable, white-opaque photoimageable solder resist with a claimed resistance to yellowing, and
Elpemer SD 2691 TSW marking ink is applied by screen printing and developed in aqueous-alkaline media. The latter corresponds to the flame class V-0 according to UL 94, and meets the requirements of IPC-SM-840D and is halogen-free per JPCA-ES01-2003/IEC 61249-2-21.