Wafer Level Multi-chip Gang Bonding Using TCNCF

High throughput interconnection technology has been achieved using a multi-chip gang bonding process with an advanced chip on wafer (CoW) test vehicle (TV). The TV had 30 µm of fine-pitch copper pillar (CuP) and the bonding test was performed using non-conductive film (NCF). Therefore, all the steps including NCF lamination, wafer back-grinding and sawing, and thermo-compression bonding (TCB) were accomplished at the wafer level. Firstly, a layer of non-conductive film (NCF) was laminated on top of the wafer prior to back-grind and saw processes. Secondly, eight multi chips of 6x8 mm2 and 4x8 mm2 having 200 µm thickness were attached and aligned serially on the interposer wafer. For micro-bump interconnection, parallel bonding for the eight chips was applied for a few seconds after the serial chip attach process. Visual inspection and measurement confirmed the lateral fillet coverage was less than 110 µm without resin bleed-out and creeping. Destructive and non-destructive analyses were performed to examine solder joint formation & void inspection. Finally, reliability test was performed to confirm stability of the bonding process in a moisture resistance test (MRT) of L2Aa (60'C/60%RH, 120hrs) and L3 (30'C/60RH%, 192hrs) and temperature cycle (T/C) B 1000x. Electrical resistance was measured by probing for micro-bumps that are daisy-chained together. The resistance showed negligible change in upper and lower limit and no electrical failures or delamination occurred after reliability conditioning.