Methods for enclosing a thermoplastic package

Abstract

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. A lid is welded to the frame after a die is attached to the flange.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of application Ser. No. 10 / 767,309, filed Jan. 29, 2004, which claims the benefit of provisional Application No. 60 / 443,470, filed Jan. 29, 2003.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] Not Applicable BACKGROUND OF THE INVENTION [0003] This application relates to circuit packages for integrated circuits and, more particularly, to circuit packages that include metal flanges and high-temperature thermoplastic frames. [0004] Semiconductor and other integrated circuit devices (sometimes referred to as “chips” or “die”) are typically mounted inside circuit packages to protect the die and to facilitate electrically, mechanically and thermally connecting the die to printed circuit boards, heat sinks and the like. A typical circuit package includes a base (commonly referred to as a “slug” or “flange”), a protective insulating housing and leads extending through the housing. Inside t...

AI Technical Summary

Benefits of technology

[0010] The present invention provides a low piece-count, low cost circuit package that can withstand high die-attach temperatures and can provide a hermetically sealed air cavity for a die, without the use of adhesives. The circuit package design employs a number of mechanical features and compositions to achieve this hermeticity and temperature tolerance. This combination also provides a circuit package that exhibits better electrical and thermal conductivity and mechanical integrity than conventional circuit packages.

[0017] Compositions of the flange, frame and leads provide matching coefficients of thermal expansion (CTE), thus reducing stress on the respective junctions between these parts. These compositions also provide good thermal conductivity by the flange and good electrical conductivity by the leads and the flange. In one embodiment, the flange is made with a high copper content, augmented by a small amount of zirconium, silver or other material. In another embodiment, the leads are made with a high copper content, augmented by a small amount of iron, phosphorus, zinc and / or other material. In yet another embodiment, graphite flakes in the frame form a moisture barrier. These graphite flakes and other additives match the CTE of the frame to the CTE of the flange. An optional film can be applied to the exterior or interior of the frame and / or lid to further reduce moisture infiltration into the air cavity.

Problems solved by technology

The high temperature used to attach a die to a flange can damage or deform plastic, however ceramic materials are able to withstand this high temperature.

This process is very expensive, and the thermal conductivity of the resulting alloy is limited.

Improved thermal conductivity can be achieved through the use of copper-molybdenum-copper laminated flanges fabricated by an infiltration process followed by a lamination process, however these processes are very expensive.

This approach enables use of low-temperature plastic for the frame, however adhesives used to attach the frame to the flange and to the lid perform less than satisfactorily.

These adhesives often create imperfect seals or permit gaps to open during use of the circuit package.

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