Electricity: conductors and insulators – Boxes and housings – Hermetic sealed envelope type
Patent
1993-12-28
1996-07-02
Kincaid, Kristine L.
Electricity: conductors and insulators
Boxes and housings
Hermetic sealed envelope type
174 59, 361707, 361714, H05K 506
Patent
active
055324304
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a housing for energy-dissipating electronic components mounted on a double-faced printed circuit board. The circuit board is fastened to a heat-conductive metal substrate, which is integral with the housing. A connector also integral with the housing is electrically connected to the circuit board. The connector is located on the same side of the substrate as the printed circuit.
2. Discussion of Related Art
Today, using a printed circuit board on a heat-conductive metal substrate is frequently proposed as solution for the problem of dissipating the heat of power components. Two sets of copper lands are printed on the either side of a not very thick flexible layer of polymide-type or Kapton-brand insulating material, and the double-faced circuit thus formed is bonded onto the metal substrate. In the field of automobile electronics, for instance, this is referred to as a "power flex board". This field, as well as others, requires products that have high-reliability and low cost even though they are subject to severe operating conditions. Temperature is one of the factors affecting this reliability. For example, the electronic switches for power actuators controlled by an electronic computer, dissipate energy and it is absolutely necessary to cool them in order to preserve their reliability. The power flex boards described above assure the necessary cooling.
A problem remains, namely the placement of the connector. Use of SMC-type (surface-mounted component) connectors has been proposed, but it is difficult to solder on the side of the metal substrate where the flexible board is located, as the printed circuit and its components do not withstand two solderings. Soldering the connecting lugs of a conventional connector to one edge of the flex board that protrudes from the metal substrate and then introducing the board-connector assembly into the housing and, finally, to fastening both of them to the housing with screws, clips, or other similar means, has also been proposed. However, this solution also has drawbacks. Between the time when this board connector is assembled by soldering the connections, and the time of its attachment, it undergoes stresses because of the lack of rigidity of the board connector assembly. Thermal resistance between the metal substrate of the board and the housing degrades the reliability of control and drive devices, such as the computer devices referred to above. Finally, the housing must be shaped so as to have a recess, shaped like a tub, to hold the free ends of the connecting lugs of the connector.
SUMMARY OF THE INVENTION
The present invention is directed to overcoming all these problems. Thus, it provides a housing of the above mentioned type wherein the metal heat-conductive substrate comprises a cutout adapted to support the connector, which is soldered on the face of the printed circuit that faces the substrate at the location of the cutout.
In accordance with the invention, the connector is fastened to the housing indirectly, via the substrate, and the combination of the printed circuit and the connector assembly is no longer flexible before attachment to the housing. Finally, the conventional connector of the housing in accordance with the invention is used, so to speak, as a reverse SMC component, that is to say, through the use of a printed circuit soldering face opposite that of the SMC components.
The invention permits a conventional connector to be used and fastened rapidly to the substrate. Mounting this connector is thus greatly simplified. After soldering the components and the connector, the rigid assembly can easily be fastened to the housing.
The substrate cutout is preferably provided at the center of an edge. Furthermore, the connector is preferably separated from the dissipative components by an electromagnetic shielding lip. Also, the housing is preferably open on the side of the substrate opposite the side to which the printed circuit is fastened, which eliminates
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patent: 3989333 (1976-11-01), Cauldwell
patent: 4339260 (1982-07-01), Johnson et al.
patent: 4763225 (1988-08-01), Frenkel et al.
patent: 5103375 (1992-04-01), Cottingham et al.
patent: 5321583 (1994-06-01), McMahon
patent: 5392197 (1995-02-01), Cuntz et al.
patent: 5414597 (1995-05-01), Lindland et al.
Horgan Christopher
Kincaid Kristine L.
Societe d'Applications Generales d'Electricate et de Mecanique S
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