Flip-chip assembly of protected micromechanical devices

A method of fabricating land-grid array devices for semiconductor chips having an integrated circuit including a plurality of micromechanical components configured in a plane in the central portion of said chip and a plurality of metallic terminals disposed in peripheral portions encircling said chip, comprising:

• providing a wafer having a surface including a plurality of said chips;
• coating said wafer surface with a protective material;
• selectively etching said protective coating, exposing said terminals of each of said chips;
• depositing one solder ball on each of said exposed terminals;
• separating the resulting composite structure into discrete chips;
• providing an electrically insulating substrate having first and second surfaces and an opening, said surfaces being substantially parallel to each other, a first plurality of metallic contact pads disposed on said first surface in proximity to said opening, and a second plurality of metallic contact pads disposed on said first surface remote from said opening;
• mounting one of said discrete chips on said first plurality of substrate contact pads by forming solder joints, spaced apart by a gap;
• controlling the height of said solder joints to maintain uniformity, thereby positioning said substrate in a plane parallel to said components plane;
• filling said gap with a polymeric encapsulant, surrounding said opening by a continuous frame of encapsulant;
• removing said protective material, thereby exposing the surfaces of said components;
• and
• attaching a lid to said second substrate surface, thereby positioning said lid in a plane parallel to said plane of said components.