Using stencil, screen printing, and spin coating techniques, Henkel’s Ablestik 8000 series, wafer backside coating (WBC) reportedly enables the deposition of die-attach materials to the wafer backside down to a thickness of 20 &#181m on wafers as thin as 100 &#181m and up to 300 mm in diameter. Unlike conventional dispensing methods, printing or spin coating materials onto the wafer is said to deliver a tightly controlled, high UPH for high-volume die attach adhesive deposition. Bondline thickness is controlled to customer specifications, and chip footprint is maximized through the elimination of the fillet and repeatable material uniformity to ensure no die tilt. Once the wafer is coated, material is then B-staged where the material is advanced to a secondary, partially cured film-like, tack-free state, following which the wafer can be stored for later use.

The materials are available in conductive and non-conductive formulations and have been engineered to address the requirements of smaller die sizes to enable high throughput production of packages such as COLs, SOs, TSOPs, and QFNs, that have tight design tolerances and require controlled flow. Additionally, WBC material is a viable and effective alternative to standard solder-based processes for discretes and small power ICs. It is in production for single die configurations, and is said to become an alternative to film for stacked die applications. Henkel Corp. Irvine, CA. www.ablestik.com