Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electrical power distribution systems and devices
Reexamination Certificate
2001-10-17
2003-05-13
Chervinsky, Boris (Department: 2839)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electrical power distribution systems and devices
C361S704000, C361S707000, C361S760000, C257S675000, C257S706000, C257S718000, C174S016300, C165S080300, C165S185000
Reexamination Certificate
active
06563696
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates generally to the communications field, and, more particularly to a solderless assembly for quickly connecting and disconnecting a laser assembly made up of a laser diode and a heatsink to a printed circuit board (PCB) used in the communications field.
B. Description of the Related Art
Printed circuit board (PCB) assemblies are used in computers, communications equipment, televisions, and many other products. In a typical PCB assembly, many electrical components are attached to the top and bottom surfaces of a PCB. Since the electronics manufacturing industry is highly competitive, it is important to maximize the throughput of processing PCB assemblies and to attach functional electrical components to the PCBs.
The manufacturing of PCB assemblies involves many processes, one of which is surface mounting components to PCBs. In addition to maximizing the throughput of processing PCB assemblies, it is also becoming important to accurately mount a large number of very small components to the PCB assemblies.
One major problem in mounting components on PCBs and the like is the connect/disconnect function. It is important that various components of the system be removable and/or possible to disconnect so that normal maintenance and testing, as well as changes and updates to the system, can be accomplished. Sometimes components that are permanently mounted onto a PCB (typically via soldering) may be defective. If such permanently-attached components are found to be defective, it is difficult to remove such components for repair without damaging or destroying the component and/or the PCB. Thus, it is essential that such components be easily removed from a PCB, without damaging or destroying the PCB, especially in the case where the component is defective.
One component that is typically permanently fixed (usually via soldering) onto a PCB is a laser diode. A laser diode, also known as an injection laser or diode laser, is a semiconductor device that produces coherent radiation at a center wavelength when current passes through it. Laser diodes are used in, for example, optical fiber systems, compact disc (CD) players, laser printers, remote-control devices, and intrusion detection systems.
Conventionally, a laser diode is provided with a heatsink on either a top or bottom surface of the laser diode. A heatsink is typically just a piece of metal that dissipates the heat generated by an optical or electronic component. There are three ways an object can dissipate heat: radiation, conduction, and convection.
Radiation, as the name suggests, means that the heat is simply radiated away from the object, through electromagnetic radiation (photon transport). This effect is not bound to gas or other substances surrounding the heatsink. Radiation will even take place in a vacuum. How well an object can radiate heat depends upon the material and the color.
Conduction is the exchange of kinetic energy between molecules. Less energetic (lower temperature) particles gain kinetic energy by colliding with more energetic particles (through physical contact). Since direct contact is required, a heatsink (surrounded by air) cannot get rid of significant amounts of heat using conduction. However, conduction is the effect that is responsible for the heat transfer from the hot component to the heatsink.
Convection is heat transfer by movement of a heated substance (gas or liquid). This means that the heat is transferred to the molecules of the gas (or liquid) surrounding the hot object, and then transported away through movement of molecules. If the gas or liquid around the object is forced into movement (e.g. by a fan blowing air across a heatsink), then this is called forced convection.
In a conventional arrangement as described generally in U.S. Pat. No. 5,324,387, a laser diode connects to a heatsink (usually with solder or screws), the heatsink connects to the PCB (usually with solder or screws), and the leads of the laser diode are soldered to the PCB to electrically couple the laser diode to the PCB. Once a laser diode is electrically coupled to the PCB, it is desirous to test the laser diode to see if it is functional. If the laser diode is defective or nonfunctional, it is further desirable to remove and repair, or remove and replace the defective laser diode. Unfortunately, if the leads of the defective laser diode are permanently soldered to the PCB, it is very difficult to remove the laser diode from the PCB without damaging or destroying the laser diode and/or the PCB.
Thus, there is a significant need in the art to provide a mechanism that temporarily attaches and electrically connects/disconnects a laser diode (or other electrical or optical component) and a heatsink to a PCB.
SUMMARY OF THE INVENTION
The present invention solves the problems of the related art by providing a solderless assembly for quickly connecting and disconnecting a laser diode and a heatsink to a printed circuit board (PCB) used, for example, in the communications field.
In accordance with the purpose of the invention, as embodied and broadly described herein, the invention comprises an apparatus for connecting and disconnecting a laser diode having at least one lead to a first side of a printed circuit board, the laser diode extending through a cutout portion of the printed circuit board, comprising: a heatsink connected to a second side of the printed circuit board; a connection assembly connected to the first side of the printed circuit board and connecting the laser diode to said heatsink; a compressible contact carrier interposed between the laser diode and the printed circuit board, wherein a portion of a connection force provided by said connection assembly sandwiching the laser diode and said compressible contact carrier between the printed circuit board and said connection assembly, is transferred through the at least one lead of the laser diode, to said compressible contact carrier, and electrically connects the at least one lead of the laser diode with at least one pad of the printed circuit board.
Further in accordance with the purpose of the invention, as embodied and broadly described herein, the invention comprises a method of connecting a laser diode having at least one lead to a first side of a printed circuit board, the laser diode extending through a cutout portion of the printed circuit board, comprising: connecting a heatsink to a second side of the printed circuit board; interposing a compressible contact carrier between the laser diode and the printed circuit board; and connecting the laser diode to the heatsink, via a connection assembly, wherein a portion of a connection force provided by the connection assembly sandwiching the laser diode and the compressible contact carrier between the printed circuit board and the connection assembly, is transferred through the at least one lead of the laser diode, to the compressible contact carrier, and electrically connects the at least one lead of the laser diode with at least one pad of the printed circuit board.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
REFERENCES:
patent: 4731693 (1988-03-01), Berg et al.
patent: 4933808 (1990-06-01), Horton et al.
patent: 4985805 (1991-01-01), Riedel et al.
patent: 5109320 (1992-04-01), Bourdelaise et al.
patent: 5298686 (1994-03-01), Bourdelaise et al.
patent: 5924290 (1999-07-01), Yoshino
patent: 5960535 (1999-10-01)
Anderson, Jr. Richard L.
Harris David B.
Jablonski Edward J.
Walter Thomas A.
Cammarata Michael R.
Chervinsky Boris
Ciena Corporation
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