1. Materials

1.1 Substrates

The same processes are used to manufacture alumina for hybrid circuits, whether as a base substrate or a multilayer substrate.

The process begins by formulating a slip comprising :

• calcined alumina powder, as fine as possible;

• binders and plasticizers ;

• wetting and dispersing agents ;

• solvents.

This slurry is ground in roller mills to ensure homogeneous mixing and calibration.

The slurry is then put into pressure tanks to feed the spreading machines, and poured onto a stainless steel or polyester belt. The whole process advances continuously...