Glass manufacturing – Processes – Fusion bonding of glass to a formed part
Reexamination Certificate
1999-01-28
2001-02-27
Silverman, Stanley S. (Department: 1731)
Glass manufacturing
Processes
Fusion bonding of glass to a formed part
C065S059240, C065S059260, C065S059700, C065S152000, C065S154000, C065S155000, C065SDIG001, C065SDIG001, C438S106000, C438S121000, C438S123000
Reexamination Certificate
active
06192709
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a ceramic packaging assembly process and, more specifically, to a method of embedding a metallic lead frame into molten glass.
2. Brief Description of the Prior Art
In the fabrication of semiconductor devices, an often required step is that of embedding metallic members, generally wires and/or the lead fingers of a lead frame, into a reflowed molten glass and permitting the glass to harden around the metallic member. This fabrication step generally requires that a large mechanical pressure be applied to the metallic members which are disposed over the molten glass, generally by an unheated or heated thermode or the like. The thermode or the like drives the lead fingers into the molten glass and applies the force until the glass hardens, whereupon the thermode or the like is withdrawn. This pressure results in residual overstressing of the glass-enclosed metal with resultant cracking of the glass.
SUMMARY OF THE INVENTION
In accordance with the present invention, the above described problems of the prior art are overcome and there is provided a method and system for embedding magnetically attractable metal in glass without the presence of the cracking problem.
Briefly, a conventional electromagnet magnetically pulls the metallic member, such as a wire, lead frame or lead frame finger, which is now formed of a magnetically attractable material, into the molten glass and retains the metal in the glass until the glass has hardened. The magnetically attractable material can be, for example, Alloy
42
(iron-nickel alloy commonly used in integrated circuit packaging) and Kovar (an iron-nickel alloy). Since there are no physical forces exerted on the glass, the probability of fracture of the brittle glass is materially reduced.
REFERENCES:
patent: 3349352 (1967-10-01), Zandt
patent: 3487271 (1969-12-01), Laffert, Jr.
patent: 3909210 (1975-09-01), Huttner
patent: 4157611 (1979-06-01), Ohwaki et al.
patent: 5076204 (1991-12-01), Hisamune
patent: 5950069 (1999-09-01), Groothuis
Brady III Wade James
Colaianni Michael P.
Silverman Stanley S.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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