Cyanate ester die attach material for radiation hardened electronic packages

Until recently, the choice of die attach materials in hermetic packaging for space applications has been limited to three types: silver-glass, gold-silicon eutectic, and polyimide film or paste. The performance of each die bond material varies with die size and actual package design, and no single material has given optimum performance for every type of packaging configuration. As a result, selection of the appropriate material has become a complicated procedure where production processes must be continuously modified to meet quality, reliability and performance goals. However, the use of solvent free, polymeric materials such as cyanate ester have great potential as universal die bond adhesives for single chip modules. Details of the qualification process for use of cyanate ester die attach material within radiation hardened memory modules is presented in this paper. A package was subjected to testing as per MIL STD 883E to assess the quality of the die bond, and the effect of cyanate ester on any other subsequent process steps. Based on the results obtained, cyanate ester has become the clear choice for the die attach material for all single chip modules at LMFS. Not only did it prove to be the superior die attach material in this case, it also provided additional benefits such as significantly reduced cycle times and overall manufacturing costs