Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1999-11-22
2001-02-27
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S100000, C522S102000, C522S090000, C522S099000, C522S122000, C522S172000, C522S168000, C522S171000, C522S109000, C522S148000
Reexamination Certificate
active
06194482
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a sealing material for the underfilling of electronic and electrical components, which are sealed in an underfilling process for protection from environmental influences and to improve the resistance to fatigue of the solder connections of the components.
Sealing materials are known that consist of two-component epoxy resins, and that either must be mixed before processing or must be stored as a pre-mixture at −40° C. at room temperature, they are available only for a few hours before they harden and become unusable. Disadvantages of this prior art include, on the one hand, the additional procedural step of the mixing of the two components before processing, and on the other hand the storage at low temperatures such as −40° C. (see “Encapsulants used in Flip-Chip Packages,” D. Suryanarayana, T. Y. Wu, J. A. Varcoe, IBM Microelectronics, IEEE Transact., Hybr., Manuf. Techn., Vol. 16, No. 8.858; 1993, and “Underfilling for Flip-Chip Mounting,” M. Norris, Camelot Systems S.A. Conference proceedings “Adhesives in Electronics,” Berlin 1994).
There is thus a need for sealing materials of this type that do not have to be mixed before processing and do not require storage at low temperatures.
SUMMARY OF THE INVENTION
It is an advantage of the present invention to provide a sealing material that can be stored at room temperature for a longer period of time and that is suitable for use as a sealing material for the underfilling technique for the protection of components from environmental influences and for the improvement of the resistance to fatigue of the contained soldered connections.
The present invention provides a mixture of an epoxy resin, a siloxane, and a filler material (whereby the filler material may not exceed a certain grain size) forms a three-phase system that is stable in the liquid state, in which the filler material is homogeneously distributed and epoxy/siloxane form a stable emulsion.
In an embodiment, the present invention is a casting resin formulation comprising the following components: an epoxy resin; a siloxane; a filler material with a maximum grain size less than 20 &mgr;m; a photo initiator; and a thermal initiator.
In addition, the present invention is directed towards the use of such a casting resin formulation in the underfilling of electronic components.
Other objects and advantages of the present invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawing.
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Lehner Barbara
Sezi Recai
McClendon Sanza L.
Schiff & Hardin & Waite
Seidleck James J.
Siemens Aktiengesellschaft
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