Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1996-05-03
2003-09-02
Chang, Richard (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S840000, C361S748000, C361S760000, 43, C209S564000, C324S759030, C174S068300
Reexamination Certificate
active
06612022
ABSTRACT:
TECHNICAL FIELD
The present invention relates, in general, to printed circuit board manufacturing. In particular, the present invention relates to methods and systems for manufacturing high-density printed circuit boards with increased numbers of test points.
BACKGROUND OF THE INVENTION
Current electronic product manufacturing technology includes the fabrication of a printed circuit board (“PCB”), the soldering of electronic components to the PCB, and the electrical testing of the completed PCB. One technique used in the above-summarized process involves the use of “test points”. At various locations on the PCB, conductive pads (i.e., test points) are disposed, and connected to predetermined circuitry. After the PCB has been populated with components, electrical contact is made to the test points and appropriate testing is performed. As the number of test points is increased, more precise diagnostics can be performed, such that more efficient diagnostics and repair are facilitated.
The advent of higher density electronic packaging techniques, taken in connection with the decrease in size of PCBs, have made the above-described testing difficult. For example, Personal Computer Memory Common Interface Architecture (“PCMCIA”) circuit cards use small, densely populated PCBs. Due to the complexity of these cards, many test points are required to fully facilitate testing. However, due to the small size and high parts density of these cards, locating free space to accommodate sufficient numbers of test points is difficult.
In particular, a PCMCIA PCB may be densely populated on one or both sides thereof. Little space is left on the board for test points. Furthermore, even if some test points could be allocated, they may be positioned such that automated test equipment can not reliably contact them. Even further, PCMCIA PCBs are thin (18-21 mils), and require mechanical support under any test points. Without mechanical support, electrical test probes might flex or penetrate the PCBs, ruining them. Unfortunately, the high densities of PCMCIA PCBs complicate mechanically supporting them during testing.
In view of the above, the testing and repair of PCMCIA PCBs are impaired. For example, testing using reduced numbers of test points does not produce very precise localization of malfunctioning aspects of the populated PCB. Further diagnostics, usually performed manually, are therefore necessary. Substantial expense is thus incurred in diagnosing and repairing these PCBs. Often, malfunctioning boards are simply discarded due to the high repair cost. Therefore, the lack of adequate numbers of test points on PCMCIA PCBs directly increases product costs.
The present invention is directed toward a solution to the above-noted problem.
DISCLOSURE OF THE INVENTION
In a first aspect, the present invention includes a method for manufacturing a printed circuit board (“PCB”). The method includes providing the PCB having a main area and an auxiliary area. The main area has at least one electronic component disposed thereon and the auxiliary area has at least one test point disposed thereon. The PCB is tested by electrically contacting the at least one test point. Thereafter, the auxiliary area is removed from the PCB.
As an enhancement, after the testing, the PCB may be repaired as a function of the testing. Further, testing and repair may be repeated until a desired level of functionality is achieved. During the testing, the PCB may be mechanically supported on a side opposite the at least one test point.
As a further enhancement, the auxiliary area may be removed by a cutting process using, e.g., a router, a laser or a water knife. Thereafter, at least one edge of the PCB created by said removing may be sealed using, e.g., a conformal insulative coating.
In another embodiment, the main area of the PCB corresponds to a PCMCIA PCB.
In yet another embodiment, the present invention includes a PCB having a main area and an auxiliary area. The main area is adapted to received at least one electronic component and the auxiliary area has at least one test point disposed thereon. The auxiliary area is contiguous with the main area and is removable therefrom by cutting. Further, the PCB includes at least one metallic trace disposed between and electrically contacting the at least one electronic component and the at least one test point for facilitating testing of the at least one electronic component by contacting the at least one test point.
As an enhancement, the PCB may include an internal wiring layer containing the at least one metallic trace. Further the PCB may have a thickness of less than 25 mils and the main area may be a PCMCIA PCB.
The present invention has many advantages and features associated with it. High testing visibility is provided to the circuitry of the populated PCB thereby enabling thorough testing. More efficient diagnosis and repair is facilitated thereby, and yields are therefore increased. Also, the use of test points in the auxiliary area allows for denser PCBs since no space is required in the main area for test points or mechanical stabilizers. Further, mechanical stress related PCB damage due to “main area” testing is reduced (e.g., solder joint cracking). Moreover, revisions to the PCB can be made without having to redesign a test fixture, thereby expediting time-to-market for new designs and lowering overall costs. Also, similar PCBs can be testing using a same test fixture; therefore, less test fixtures are needed, again lowering costs. In short, the techniques of the present invention advance the art of printed circuit board based product manufacturing.
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patent: 3830956 (1974-08-01), Wootton et al.
patent: 4426773 (1984-01-01), Hargis
patent: 4812742 (1989-03-01), Abel et al.
patent: 5031073 (1991-07-01), Chang
patent: 5131140 (1992-07-01), Zimmer
patent: 5258323 (1993-11-01), Sarma et al.
patent: 5416428 (1995-05-01), Swart
patent: 5680936 (1997-10-01), Beers
patent: 5687476 (1997-11-01), Van Liere
PCMCIA Process Selection, Circuits Assembly, Jul. 1994 (p. 30-33).
“Text Fixture Solutions for PC Cards,” Jim O'Leary, TTI Testron Inc., Austin, TX.
Fiske Thomas Alden
Gale Alan Andrew
Korowitz Simon
Barron David
Chang Richard
Invensys Systems Inc.
Powsner David J.
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