Patent ID: 7352039

Claim:
A microelectronic assembly, comprising: a MEMS substrate; a MEMS device on the MEMS substrate, the MEMS device having a MEMS component which is movable relative to the MEMS substrate; a cavity area surrounding the MEMS device at least partially formed by the MEMS substrate; and a material having a variable viscosity filling the cavity area, wherein the material has a viscosity value high enough to prevent foreign material from contacting the MEMS device during a manufacturing packaging process but later allows the MEMS device to operate freely at a normal operating temperature, wherein the material is one of (i) a bismuth-based alloy solder compound with a melting point equal to or greater than 47° C. or (ii) a translucent plastic polymer with a melting point above 100° C. but below 150° C.