Table 2 shows that the modulus of elasticity for 96% alumina is very high, and 100 times higher than for epoxy resin. We would therefore expect the hybrid microcircuit to be much more rigid than its laminate equivalent. It is also five times stronger in tension, and has ten times the shear strength. Although we haven’t stated a value, it is also much harder.
So why don’t we use more alumina substrates? Apart from their substantially higher cost, the main reason is that an alumina substrate is much more brittle: this kind of ceramic ‘tile’ will break rather than bend, and is subject to chipping damage. Surface defects, such as scores, can also reduce the strength of the part. We say this to make the point that, as with all engineering materials, it is the total of the characteristics which is usually important, rather than any specific characteristic.