Modular sensor chip design for package stress evaluation and reliability characterisation

A modular test chip comprising an array of 2 mm square modules has been designed and fabricated. The maximum chip size can be up to 10 mm square, i.e. a 5 × 5 array of modules. The motivation behind the test chip is primarily the need to address reliability concerns in the use of copper wire bonding. It is known that the move to replace gold wire bonding with copper, driven primarily by the escalating price of gold, leads to reliability challenges at the interfaces between the wire bonds, the bond pads and the mould compound. Its function is to address. The chip comprises daisy chain structures to monitor changes of wire bond resistance and leakage current, large and small area stress sensors to measure stress on the chip associated with die attach and moulding, and comb and triple track sensors to study corrosion and moisture penetration related to mould compound.