"Non-piercing" ? A must for flip chips!

Compared to the COB process (wire bonding) the flip-chip process is significantly more intolerant to pre-existing mechanical die damage. This can be caused by the mechanical pretreatment of the dies, the thinning and sawing of the wafers, but above all by the cutting out of the dies during the assembly process. The pre-existing damage constitutes a reliability risk, as thermal shock testing demonstrates. The international standards MIL-STD 883G, JESD22-B118, ESCC 2049000 currently give too little consideration to these aspects. AEMtec GmbH, as a service specialist for the assembly of unhoused chips, has many years of experience in COB and flip-chip processes. The following article describes pre-existing die damage and proposes measures to minimise it.