Problem of Cracking and Warpage of Ceramic/Glass-Ceramic Film on Ceramic Substrate

There was a problem of cracking of a multi-layer/multi-coated ceramic film on alumina substrate. This cost the company in the manufacturing of the coated substrate for the electronic industry.

The following approach was taken. DTA and Dilatometer were used to test the phase change and coefficient of thermal expansion (CTE) of the ceramic paste. This consultant also ran a TGA to determine the weight loss due to evaporation of the organics at different stages during heating. Based on all the information, the formulation of the ceramic paste / coating was optimized and printed on alumina substrate. After sintering using an optimized sintering profile, the warpage of the substrate was measured. Another layer of ceramic paste was printed, fired and warpage was measured. Similarly several layers were printed and fired. At the same time a test coupon of the glass / glass-ceramic paste was made into a bulk sample and CTE was measured using a dilatometer. Every time the ceramic substrate was refired, the test coupon was also refired in the dilatometer and the CTE was measured. The glass / glass-ceramics warpage and CTE changed with refire. After plotting the results of CTE vs warpage, corresponding CTE was determined when warpage was almost zero. At this point the multilayer ceramic coating did not exhibit any cracking and it adhered well on the substrate. The final warpage after 31 firings was 0.002" / inch. And the CTE (100 C-900 C) was 7.2 x 10-6 /0C after 30 refires which is close to CTE of alumina. This same technique can be applied to solve the problem of cracking band delamination of any glass / glass-ceramics / ceramics coating or paint.

To see the resume of the expert associated with this case study, see the link below.