Alpha POP-959 Pb-Free, no-clean solder paste is designed to deliver repeatable paste volumes for PoP assembly. Provides flux and solder powder. Designed to minimize expensive rework and scrap. Is said to offer resistance to shear forces associated with PoP dip application equipment. Reportedly maintains rheology for at least 24 hrs. Is said to be ideal for 150 to 300 µ offset chip scale packages, while leaving a clear, colorless, residue with high electrical resistivity.

Cookson Electronics Assembly Materials, www.cooksonelectronics.com