Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – With work feeding or handling means
Patent
1991-12-27
1993-03-30
Simmons, David A.
Adhesive bonding and miscellaneous chemical manufacture
Surface bonding means and/or assembly means therefor
With work feeding or handling means
156556, 228212, 228237, 228243, 264230, B32B 3100
Patent
active
051980665
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for mounting covers of ferromagnetic material on capsules, substrates and hybrid modules for semiconductor components, whereby a capsule cover is applied over an opening in a capsule with a conductor-bonded circuit mounted therein, there being between the capsule and the cover a fusible film of soldering metal or other fusible means, the cover being soldered to the capsule by the capsule provided with the cover being heated in an oven often in a protective gas atmosphere.
In mounting a finished circuit in its capsule, bonding is accomplished via access wires to the capsule's electrical conductor (legs or contacts designed for surface mounting) by special robot machines. During this operation, which is one on the assembly line principle, the capsules which are still not provided with covers are placed in special fixtures from which they are automatically retrieved for the bonding work and returned thereto. After this coupling they are taken up by hand, a cover provided with solder in the form of a foil is placed thereon, the cover is held in place by a clamp and the capsules are advanced on a conveyor belt through an oven with a protective atmosphere (nitrogen, helium or argon), where they are heated so that the cover is soldered securely in place, as a rule less than about 360.degree. C. In certain cases, instead of metal solder, glass or similar fusible material can be used where the melting point can be higher.
This method has several disadvantages. On the one hand, the automatic chain is broken, and on the other hand a repetitive manual step is introduced of the type requiring attention without stimulation, which results in faulty articles. In view of the fact that the testing of both the connections and the function of the circuit itself is often done automatically in connection with the automated bonding, these faults will affect otherwise perfect and properly connected, and therefore potentially expensive, circuits. Furthermore the clamps used have a limited life due to the high temperatures.
It is therefore a purpose of the present invention to provide automatic cover application as well, thus reducing both the number of rejects and time consumed. Another purpose is to enable the electronic semiconductor circuits to be covered in an inert atmosphere. A third purpose is to make use of the fact that the open but otherwise completed circuits exit from the covering station lying in fixtures, during additional treatment steps such as marking.
The advantages and characteristics of the invention are achieved in a device of the type described by way of introduction which has those characteristics disclosed in the attached claim 1.
The invention is thus based on the ferromagnetic capsule covers being held by magnets and being relatively accurately centered over the capsules. The capsules lie with a certain amount of lateral play in the fixtures and when the cover portion is mounted by means of magnets, the capsules will be centered under the cover, within proper tolerances. The fixtures with the cover portions applied thereto then proceed into an oven via a slotted opening. When working with a protective gas, there is a certain amount of overpressure in the oven, and the fixtures provided with numerous openings will therefore be cleared of air in the opening, and this also applies to the circuit capsules themselves which have not yet been sealed by means of the covers. When the fixtures with their cover portions have arrived into the oven, the pushers are heated and assume another shape, and they press the covers against the capsules with the desired pressure. As the temperature increases further, the intermediate fusible layer melts and the covers are soldered or fused in place, and the fixture exits thereafter from the oven. Marking and other such operations can now be performed on the capsules in their fixtures after the cover portions have been removed.
In order to accomplish the extension and retraction of the cover holders as required, it is possible to use either a me
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patent: 4126758 (1978-11-01), Krumme
patent: 4384906 (1983-05-01), Molinari et al.
patent: 4661886 (1987-04-01), Nelson et al.
patent: 4767589 (1988-08-01), Takaoka et al.
patent: 4950258 (1990-08-01), Kawai et al.
Engel, Jr. James J.
Simmons David A.
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