Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame – With heat sink means
Reexamination Certificate
2001-07-26
2004-05-04
Jackson, Jerome (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
With heat sink means
C257S707000, C257S676000, C257S785000, C372S036000, C361S719000
Reexamination Certificate
active
06730993
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates generally to the communications field, and, more particularly to an assembly for quickly connecting and disconnecting a laser diode, having a heatsink provided thereon, 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. A heatsink is nothing more than 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), having a heat sink provided thereon, to a PCB.
SUMMARY OF THE INVENTION
The present invention solves the problems of the related art by providing an assembly for quickly connecting and disconnecting a laser diode, having a heatsink provided thereon, 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 a connect and disconnect assembly for connecting and disconnecting a laser diode having at least one lead to a printed circuit board, including: a heatsink having a base plate portion and a plurality of fins extending from and integral with the base plate portion, the heatsink being connected to the printed circuit board, and the laser diode being connectable to the heatsink; and at least one laser support block interposed between the heatsink and the printed circuit board, wherein a portion of a connection force connecting the heatsink to the printed circuit board is transferred through the at least one laser support block to couple 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 an assembly to a printed circuit board, the assembly including a heatsink having a base plate portion and a plurality of fins extending from and integral with the base plate portion, a laser diode having at least one lead, and at least one laser support block, comprising: connecting the laser diode to the heatsink; interposing the at least one laser support block between the heatsink and the printed circuit board; and connecting the heatsink to the printed circuit board, wherein a portion of a connection force connecting the heatsink to the printed circuit board is transferred through the at least one laser support block to couple 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: 4342068 (1982-07-01), Kling
patent: 5621615 (1997-04-01), Dawson et al.
patent: 6084178 (2000-07-01), Cromwell
patent: 6252726 (2001-06-01), Verdiell
patent: 6304450 (2001-10-01), Dibene et al.
patent: 6404042 (2002-06-01), Sone et al.
Boyer Thomas R.
Davidson Bradley Paul
Cammarala Michael R.
Ciena Corporation
Landau Matthew C.
Olsen James M.
Soltz David L.
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