Inductor devices – With outer casing or housing – Potted type
Reexamination Certificate
1997-11-24
2001-11-20
Mai, Anh (Department: 2832)
Inductor devices
With outer casing or housing
Potted type
C336S192000, C336S090000, C336S229000
Reexamination Certificate
active
06320489
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electronic surface mount package or case and more particularly to an electronic surface mount package with an extended side retaining wall. Electronic surface mount packages are utilized in applications in which one or more individual toroid transformers are embodied within the surface mount package.
Wires coming off the transformers are electronically tied to pins or posts on the package for connection to an electronic device. Typically, the electronic surface mount packages are mounted on a printed circuit board for utilization in the electronic device.
It is widely known in the local area magnetic industry that when surface mount toroidal magnetics which are encapsulated in hard plastics go through infra-red soldering processes, the magnetic components (ferrite) can expand significantly. When using a hard epoxy type material, it has been found that the magnetic component expansion can often cause cracking of the package or case, which makes the part unusable. The electronic surface package described in the cross-referenced U.S. Pat. No. 5,656,985 provides a soft silicone type material to encapsulate (carry) a plurality of toroid transformers within the package. The toroid transformers in turn are electrically connected to a plurality of terminal posts molded within the package. In view of the foregoing, it would be highly desirable to provide an improved electronic surface mount package which avoids the cracking and expansion problems described above and in addition provides additional coverage for the terminal pins to which the toroids are electrically connected as well as additional coverage for the soft silicone type material which encapsulates the toroids within the package.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved electronic surface mount package.
According to one preferred embodiment, the present invention provides a one piece construction package (with an open bottom) with one or more terminal pins molded into the package. Each of the pins have a notched post upon which a wire is wound and soldered. The wire which is wound and soldered around each terminal pin/post is from a respective toroid transformer carried within the package. Each of the posts are notched so that the respective wires are separated from one another so as to avoid arcing. The case is open at the bottom which prevents cracking and allows for the toroidal expansion. A soft silicone type material is added to the open package to provide support (to carry) the toroid transformers. In one embodiment, the present invention also includes a reinforcement beam that is disposed laterally or sidewise across the bottom of the package to provide extra support in the mechanical strength of the case. In another embodiment, the present invention also includes an extended side retaining wall for retaining the soft silicone type material and providing additional coverage of the soft silicone material the end walls have a first height H1 to form a standoff or safe guard between the foot seating plane of the package and the terminal pins; and the outer portion of the side wall extends between the end walls such that the side wall has a second height H2 which is less than said first height H1. The mounting of the package onto a printed circuit board (PCB) with the extended side retaining wall according to the present invention allows for cleaning of the PCB with wash liquids which can flow freely under the package under the portion of the extended side wall, since the height of the extended side retaining wall (H2) is less than the height of the safeguard H1 (H2<H1). The extended side retaining wall provides for improved containment of the soft silicone material within the package. The extended side retaining wall also provides for improved coverage of the wire wrapped solder posts.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3721747 (1973-03-01), Renskers
patent: 5034854 (1991-07-01), Matsumura et al.
patent: 0 490 438 A1 (1992-06-01), None
McCormick; Surface Mount Transformers: A New Packaging Approach; Surface Mount Technology; Feb. 1993; pp. 27-31.
Wyns et al.; PSPICE Simulations and 3D-PCB Transformers for ZVS Full Bridge Converters; The European Power Electronics Association; 1993; pp. 208-214.
EPE'93 Fifth European Conference; Power Electronics and Applications; vol. 3: Electronic Power Supply System; Sep. 13-16, 1993; pp. 215.
Davis; SMT Passive Components Fit Power Electronics Applications; PCIM; Jun. 1993; vol. 19; No. 6; pp. 20-28 and 90.
Osawa; A Superminiaturized Double-Balanced SMT Mixer-Modulator; Microwave Journal; Feb. 1994; pp. 90-97.
Lyons et al.; Printed Circuit Board Magnetics: A New Approach to the Mass Production of Toroidal Transformers; ISHM '95 Proceedings; pp. 53-58.
Derebail et al.; Knowledge Based Adhesive Selection for SMT Assemblies; Proceedings 1995 International Symposium on Microelectronics; Oct. 24-26, 1995; vol. 2649; pp. 1024-1035.
Heaton James W.
Heaton Jeffrey
Lam Robert Loke Hang
Lu Peter
Pao Peter Loh Hang
Halo Electronics, Inc.
Mai Anh
Trial & Technology Law Group
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