Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-03-16
2001-04-10
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S704000, C361S710000, C361S674000, C315S046000, C362S221000
Reexamination Certificate
active
06215663
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of printed circuit board assemblies, and in particular to printed circuit board assemblies that include a heat sink.
2. Description of Related Art
Heat sinks are often used to dissipate heat from electronic components. Often, a heat sink is provided for the particular component that generates substantial heat. In many cases, however, the accumulated heat of many components necessitates the heat dissipation. In such cases, it is often more efficient and cost effective to provide a heat sink that dissipates heat from a region of a circuit board, rather than individual component heat sinks. Heat sinks are commonly required in ballast circuits that provide high voltage or high current signals to operate lamps.
U.S. Pat. No. 5,798,908, issued Aug. 25, 1998 to Herzberger et al, discloses a printed circuit board assembly comprising a printed circuit board and an integral heat sink, and is incorporated by reference herein. The heat sink of the '908 patent comprises an aluminum plate that is adhered to the printed circuit board via a hot-press process. To accommodate both through-hole components as well as surface mount components, slots are cut into the aluminum plate to create voids under select areas of the printed circuit board, to accommodate the pins of the through hole components. This arrangement is well suited for use in a ballast assembly, wherein one or more transformers include pins that serve to mechanically hold the transformer in place on the printed circuit board, as well as providing the electrical contact between the printed circuit board and the coils of the transformer. After assembly, the voids are filled, or covered by another plate, to avoid inadvertent contact with the high voltages that are typically associated with a lamp ballast.
BRIEF SUMMARY OF THE INVENTION
It is an object of this invention to provide a heat sink for a printed circuit board that allows for through-hole components, but does not require cutting voids in the heat sink. It is a further object of this invention to provide a printed board assembly with integral heat sink that is particularly well suited for ballast applications.
These objects and others are achieved by providing a printed circuit board assembly that comprises a printed circuit board and a heat sink having two surface planes. One surface plane of the heat sink is raised, and provides a surface area for contact with the printed circuit board. The other surface plane is lower than the raised surface plane. The printed circuit board extends over the lower surface plane. The distance between the raised surface plane and the lower surface plane provides space for through-hole pins that extend beneath the printed circuit board, because the underside of the printed circuit board lies on the raised surface plane. The multi-plane heat sink can be formed by an extrusion process, as well as a stamping or other process that allows for more complex patterns of surfaces.
REFERENCES:
patent: 5375039 (1994-12-01), Wiessa
patent: 5402313 (1995-03-01), Casperson et al.
patent: 5798908 (1998-08-01), Herzberger et al.
patent: 5930601 (1999-07-01), Cannizzaro et al.
patent: 6058013 (2000-05-01), Christopher et al.
patent: 0481409A1 (1992-04-01), None
Datskovsky Michael
Philips Electronics North America Corporation
Picard Leo P.
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