Cu-Pillar Flip-Chip Flux WS-641 is a water-washable dipping flux specifically designed for thermocompression bonding in flip-chip applications using copper pillars. It features a robust activator system that enhances solder wetting on mildly oxidized copper and ENEPIG surfaces. The flux can be applied at dipping depths of 10 microns or less and is halogen-free, making it an environmentally friendly option. The product exhibits excellent solderability across various surfaces and maintains uniform dipping volumes over extended periods. It is classified as M0 according to J-STD-004 and has a typical viscosity of 8 kcps. The flux is effective in achieving high yields in copper-pillar flip-chip processes and is packaged in bubble-free syringes of 10cc and 30cc. Post-reflow, WS-641 residues can be cleaned with deionized water, and optimal cleaning conditions are specified for effective residue removal. For storage, it is recommended to keep the product tip down at temperatures not exceeding 25¬8C. The flux is designed for rapid reflow conditions, with a peak temperature of 330¬8C or less to ensure good cleanability.
The flip-chip process involves taking the singulated die from a wafer mounted on a wafer dicing tape, inverting ("flipping") them and placing them onto a substrate. The substrate may be a printed circuit board, a ceramic substrate, or (in the case of 2.5D and 3D assembly) an interposer.
| Indium Corporation | |
|---|---|
| Product Category | Filler Alloys and Consumables |
| Product Number | WS-641 |
| Product Name | Flip-Chip Flux |
| Joining Process / Product Form | Braze or solder in the form of a paste. |
