Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1998-01-21
2001-02-20
Gaffin, Jeffrey (Department: 2841)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S760000, C361S772000, C361S783000, C361S810000, C361S812000, C257S687000, C257S704000, C257S787000, C257S924000, C174S050510, C174S050510, C029S841000, C029S855000, C438S126000, C438S127000, C264S272140, C264S272170, C264S272210, C264S276000
Reexamination Certificate
active
06191955
ABSTRACT:
PARTIAL WAIVER OF COPYRIGHT PURSUANT TO 1077 O.G. 22(3/20/87)
© Copyright, Dallas Semiconductor Corporation 1994. All of the material in this patent application is subject to copyright protection under the copyright laws of the United States and of other countries. As of the first effective filing date of the present application, this material is protected as unpublished material.
Portions of the material in the specification and drawings of this patent application are also subject to protection under the maskwork registration laws of the United States and of other countries.
However, permission to copy this material is hereby granted to the extent that the owner of the copyright and maskwork rights has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure, as it appears in the United States Patent and Trademark Office patent file or records, but otherwise reserves all copyright and maskwork rights whatsoever.
CROSS-REFERENCE TO OTHER MATERIALS
Applicants also incorporate by reference the mechanical drawings showing typical pin allotments and measurements for various packages for various identified products manufactured by Dallas Semiconductor Corporation.
FIELD OF INVENTION
The present invention relates generally to improved systems and methods pertaining to electronic circuit enclosure and, more particularly, to the design of housings for electronic modules and module assembly manufacturing procedures.
BACKGROUND
Circuit enclosure systems are typically electronic modules that physically enclose and/or combine together a multitude of electrical components, such as memory devices and batteries. Existing circuit enclosure systems and corresponding manufacturing procedures create a number of problems that often render existing circuit enclosure systems inoperable and/or otherwise add significant manufacturing costs to existing circuit enclosure systems. In particular, existing manufacturing techniques often produce electronic modules that have epoxy covering large portions of the electrical leads connecting the circuit enclosure system with external electrical contacts. The presence of this epoxy weakens, if not completely undermines, the desired electrical connection between the electrical lead and external electrical contacts (e.g., printed circuit boards, sockets, etc.) that electrically couple circuits embedded in the circuit enclosure systems to other, larger electrical systems. As a result, this epoxy must be removed or parts having epoxy covering portions of the electrical leads must be discarded. Existing epoxy removal techniques are expensive and time consuming, especially in terms of labor.
SUMMARY OF THE INVENTIONS
The present invention provides an improved circuit enclosure system and enhanced processes to manufacture the improved circuit enclosure system. Preferred embodiments of the circuit enclosure system or electronic module are comprised of an electrical assembly of electrical components (e.g., integrated circuits, such as non-volatile controller, timekeeping, and/or memory circuits, lithium batteries, oscillator crystals) and a cap or tub. At least one electrical component of the electrical assembly of electrical components comprises an integrated circuit packaged in a first package having at least one electrical lead electrically coupled to the integrated circuit and extending outward and away from the first package and the electrical assembly of electrical components. The cap surrounds a portion of the electrical assembly of electrical components to form a pocket or cavity between a portion of the electrical assembly of electrical components and the cap. The cap in preferred embodiments has at least one sidewall (e.g., four sidewalls) connected to a bottom surface (or the top surface, depending upon your perspective). Each of the at least one sidewalls having an end connected to the bottom surface and another end. One of the at least one sidewalls is proximately positioned to the at least one electrical lead and has at least one notch positioned in the end. Alternate preferred embodiments may have a cap that has a smooth surface, so that there is not a clear line of demarcation between the bottom surface and the side sidewall(s), which is typically the case when the cap is a hollow rectangular or cube structure with an open end, which allows objects to be placed therein. The cap is preferably comprised of injection molded plastic. The pocket is preferably filled with a sealing material or an encapsulant (e.g., epoxy). Packages in preferred embodiments of the module are generally dual in-line package (“DIP”) having four sides and said at least one electrical lead is comprised of a first plurality positioned on one side of the four sides and the second plurality of electrical leads positioned on another side of the four sides that are opposite the one side of the four sides. In these embodiments, a plurality of leads extend from opposite sides of the DIP. One or more notches preferably extend alongside the first plurality of the electrical leads and alongside the second plurality of electrical leads. The electrical lead(s) electrically couples at least one electrical component of said electrical assembly to a printed circuit board (i.e., motherboard) using standard surface mount technology and/or through holes (e.g. soldered, wired, etc.), which, in turn, electrically couples said electrical assembly to a second electrical assembly of electrical components (e.g., a personal computer system). The module may be directly connected to printed circuit board via a wired or solder connection or indirectly via a socket configured to accept the electrical leads of the module. The encapsulant in preferred embodiments is an epoxy (e.g., potting epoxy, such as that manufactured by Grace Corporation), and is typically used to provide mechanical support for all the electrical components enclosed therein and help hold all the components together. In addition, encapsulant provides a substantially water tight (or degrading cleaning solvent tight), sealed overall assembly. The encapsulant absorbs the battery electrolytes to extend the life of the battery. This absorption minimizes dendrite growth between the electrodes of the battery or between other surfaces having potential differences.
Preferred processes of assembling the module are generally comprised of the following steps (a) providing a cap, (b) filling the cap with a preselected amount of encapsulant, and (c) placing an electrical assembly of electrical components in the cap filled with the preselected amount of the encapsulant and allowing the electrical assembly to sink to a proper depth before the preselected amount of encapsulant has cured (70 degrees C. for 2 hours), wherein at least one electrical components of the electrical assembly of electrical components has at least one electrical lead and the proper depth allows said at least one electrical lead to remain substantially free of the encapsulant to create a module. Preferred processes may also comprise orienting the cap so that one of the at least one notch will extend alongside the first plurality of the electrical leads and another of the at least one notch will extend alongside the second plurality of electrical leads after step. Regarding the epoxy, the epoxy is preferably an amine cure epoxy that is comprised of fillers having fairly small particle sizes to enhance the leveling effect of the meniscus. Other changes can be made to increase the throughput of the manufacturing operations, such as loading a multitude of tubs into jig plates and adding inspection steps to inspect the finished product for quality control. Note that dispensing a controlled amount of encapsulant is important. The controlled amount may vary depending upon tub size and the size of electrical components as well as the accuracy of the equipment used to dispense the encapsulant.
The disclosed invention has the following advantages. The module system and related processes can be used to reduce the interference encapsulants (e.g., epoxy) with
Dinh Michael Quan
Guillot Joe
McLemore Linda M.
Roberts Bill
Dallas Semiconductor Corporation
Gaffin Jeffrey
Jenkens & Gilchrist a Professional Corporation
Vigushin John B.
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