Metal fusion bonding – Including means to force or clamp work portions together... – Work portion comprises electrical component
Reexamination Certificate
2001-01-04
2003-11-18
Elve, M. Alexandra (Department: 1725)
Metal fusion bonding
Including means to force or clamp work portions together...
Work portion comprises electrical component
Reexamination Certificate
active
06648204
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to the field of electronic circuits and, in particular, to an alignment weight for an electronic circuit with a floating pin field design.
BACKGROUND
Integrated circuits are a common part of modern electronic equipment. Integrated circuits typically include a large number of transistors and other circuit elements that are interconnected on a common semiconductor chip or die. Typically, integrated circuits are packaged independently and interconnected on a printed circuit board for installation in an electronic system, such as a computer.
A printed circuit board can be connected to an electronic system in a number of ways. For example, a printed circuit board can include a “floating pin field” on one side of the printed circuit board. The floating pin field includes a number of pins that are held in a fixed spatial relation by a pin field carrier through which the pins pass. The pins are electrically connected to circuit elements on the printed circuit board. A floating pin field design may be used, for example, with a printed circuit board containing an upgraded processor for a computer.
When a floating pin field design is used, the printed circuit board may be connected to a system through a socket such as a socket located on a mother board of a computer system. The socket typically includes a number of receptacles that are placed around a perimeter of the socket. The receptacles receive the pins of the floating pin field.
One problem with printed circuit boards that use a floating pin field design is in the process for soldering the pins to the bottom of the printed circuit board. Generally, the pins are held in place with a pin field carrier. The printed circuit board is patterned with a solder paste at the locations where the pins are to connect to the printed circuit board. The pins and the pin field carrier are placed on the board and the solder undergoes a reflow process. Unfortunately, sometimes not all of the solder joints created with this reflow process provide acceptable connection between the pin and the circuit elements on the printed circuit board. For example, so-called “solder bridges”—solder material that extends over a significant distance between a pin and the printed circuit board—can be formed, for example, when a pin moves away from the printed circuit board during the reflow process. These solder bridges provide a poor, brittle mechanical connection for the pin and can lead to open solder joints during use. Furthermore, when an open solder joint is detected after production, the part is typically disposed of since rework of the open solder joints is overly burdensome. This can result in a significant waste of resources in fabricating electronic modules using floating pin fields.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a more reliable technique for producing acceptable solder joints in an electronic module using a floating pin field design.
SUMMARY
The above mentioned problems with electronic modules using a floating pin field design and other problems are addressed by the present invention and will be understood by reading and studying the following specification. An alignment weight is described which is used to hold the pins in place during a reflow process.
In one embodiment, an alignment weight is provided. The alignment weight includes a body of material having first and second opposing surfaces. A number of depressions are formed in the first surface. The depressions receive pins of a floating pin field when placed on a floating pin field during connection of the floating pin field to a printed circuit board.
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In: ASM Handbook, vol. 6: Welding, Brazing and Soldering, Olsen, D.L., et al., vol. Chairmen, 993-995, (1993).
Irwin Brad C.
Waldron-Floyde Cheryl M.
Johnson Jonathan
Schwegman Lundberg Woessner & Kluth P.A.
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