Moisture evolution analysis of sealing glasses used in integrated circuit packaging

Free moisture in the cavity of a sealed hermetic integrated circuit is considered an important reliability hazard. The contribution to the cavity moisture by the packaging materials can be studied effectively using the technique of moisture evolution analysis (MEA). The technique involves passing a dry carrier gas over the sample at high temperatures and measuring its moisture uptake coulometrically. The standard moisture evolution technique has been modified to quantify the kinetics of moisture evolution from sealing glasses used for hermetic sealing of I.C. packages which are primary contributors to total cavity moisture. It is also shown that once the moisture evolution mechanisms are understood, the technique of moisture evolution analysis can be correlated to a more complex, industry standard method for free cavity moisture measurement in a sealed hermetic package (RGA-mass spectrometry). MEA can therefore be used for the process control and prediction of free cavity moisture of hermetically sealed I.C. packages.