Thermoplastic material
A circuit package for housing semiconductor or other integrated circuit devices (“die”) includes a high-copper flange, one or more high-copper leads and a liquid crystal polymer frame molded to the flange and the leads. The flange includes a dovetail-shaped groove or other frame retention feature that mechanically interlocks with the molded frame. During molding, a portion of the frame forms a key that freezes in or around the frame retention feature. The leads include one or more lead retention features to mechanically interlock with the frame. During molding, a portion of the frame freezes in or adjacent these lead retention features. The frame includes compounds to prevent moisture infiltration and match its coefficient of thermal expansion (CTE) to the CTE of the leads and flange. The is frame is formulated to withstand die-attach temperatures. A lid is ultrasonically welded to the frame after a die is attached to the flange.
1. A method for making a moisture impermeable liquid crystal polymer structure, comprising:
injecting into a mold a composition of matter comprising:
a liquid crystal polymer; and
a plurality of graphite inclusions consisting essentially of generally planar graphite flakes;
wherein the injecting of the composition is performed such that the graphite flakes form tortuous paths and are essentially organized into layers essentially parallel to a surface of said structure.
2. The method of claim 1 , wherein the composition of matter comprises between about 10% and about 70% graphite flakes.
3. The method of claim 1 , wherein the composition of matter comprises between about 40% and about 50% graphite flakes.
4. The method of claim 1 , wherein the structure includes a plurality of surfaces; and the composition is injected such that, after the injecting, the graphite flakes form layers essentially parallel to respective ones of the surfaces.
5. The method of claim 1 , wherein the structure is an electronics component package body.
6. The method of claim 1 , wherein the concentration of graphite flakes is selected to provide a desired coefficient of thermal expansion (CTE) of the structure.
7. The method of claim 6 , wherein the CTE of the structure is approximately 17 ppm/° C.
8. The method of claim 1 , wherein the melting point of the LCP is greater than 280° C.
9. The method of claim 8 , wherein the melting point of the LCP is greater than 390° C.
10. A method for making a liquid crystal polymer structure comprising the steps of:
providing a liquid crystal polymer material having a plurality of generally planar graphite flakes; and
injecting into a mold the liquid crystal polymer material having a plurality of generally planar graphite flakes in a manner to orient the graphite flakes into layers essentially parallel to a surface of the structure and forming tortuous paths through the structure which are effective to inhibit moisture infiltration.
11. The method of claim 10 , further comprising pre-drying the liquid crystal polymer material having a plurality of generally planar graphite flakes prior to the step of injecting.