Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1998-08-31
2001-06-19
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C438S613000
Reexamination Certificate
active
06249131
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ball grid array electronics assembly wherein individual solder balls of the assembly are electrically accessible for testing purposes, a method of assembling such a package, and a method of testing an electrical device which has hidden connections.
2. Discussion of Related Art
An electronics assembly often comprises a substrate and an electrical device such as an integrated circuit. An array of solder balls may be used to attach the electrical device to the substrate. The electrical device may be mounted in a manner that prevents access to the solder balls.
It may in certain instances be required to test the electrical device by making electrical contact with one or more of the solder balls individually. Since the solder balls are hidden behind the electrical device and only a small gap exists between the substrate and the electrical device such electrical testing may not be possible.
One technique for testing such an electrical device involves forming electrical traces on the substrate. The traces contact the solder balls and extend out from under the electrical device to an accessible location on the substrate. A probe connected to an electrical tester may then be used to contact the traces at the accessible location. The electrical tester may then be used to test the electrical device.
The formation of additional traces on a substrate, such as a printed circuit board, leads to a larger, more costly substrate. Additionally, the test traces occupy valuable board space and limit the input/output and/or require more substrate layers. What may therefore be required is a solution wherein individual solder balls in a ball grid array assembly can be accessed for testing purposes and wherein additional traces do not have to be made on a substrate such as on a printed circuit board.
SUMMARY OF THE INVENTION
An electronic assembly comprising an electrical device, an array of solder balls connected to the electrical device, and a sheet adjacent the electrical device. The sheet has a plurality of holes formed therethrough and a plurality of electrical lines formed thereon. Each electrical line has a first contact portion on a first surface of the sheet, a probe contact at a location away from the electrical device, and a trace interconnecting the probe contact with the first contact portion. Each ball extends through a respective hole in the sheet. Each ball is also in contact with a respective first contact portion of a respective electrical line.
REFERENCES:
patent: 5543724 (1996-08-01), Chrostopher
patent: 5691041 (1997-11-01), Frankeny et al.
patent: 5731709 (1998-03-01), Pastore et al.
patent: 5808474 (1998-09-01), Hively et al.
patent: 5834945 (1998-11-01), Akram et al.
patent: 5952840 (1999-09-01), Farnworth et al.
Blakely , Sokoloff, Taylor & Zafman LLP
Intel Corporation
Kerveros J
Metjahic Safet
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