Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1998-09-22
2001-03-20
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754090, C324S765010
Reexamination Certificate
active
06204677
ABSTRACT:
BACKGROUND OF THE INVENTION
Integrated circuits are designed to meet certain design specifications. Integrated circuits are tested before they are sold to determine whether they meet the design specifications. For relatively simple devices (i.e., devices with only a few input and output terminals (e.g., pins)), a test may involve applying signals to the input terminals, measuring the response on the output terminals, and comparing the actual response to the designed response. This comparison is performed for each permutation of input signals on the input terminals.
As errors are observed between the designed and actual output signal states, design problems in the device under test or in the load board may be pinpointed and remedied. Remedying the design problems of the device under test requires that the signals on the input and output pins of the device under test be monitored. One way of doing this uses an oscilloscope. A probe of the oscilloscope contacts each output pin for measuring the voltage on the output pin as the integrated circuit interacts with the load board. Unfortunately, some integrated circuits do not conventionally permit such monitoring. One such integrated circuit uses surface mounts such that terminals on the lower surface of the integrated circuit directly contact terminals on the upper surface of a socket. A lid over the integrated circuit compresses the terminals together when the lid is closed.
A problem with the conventional lidded surface mount device is that the surface mount integrated circuit can only interact with the load board when the lid, which covers all of the input and output terminals, is closed. Therefore, an oscilloscope probe is prevented from contacting the input or output terminals of the device under test while the device under test is interacting with the load board. Thus, the voltage states of the input and output terminals cannot be probed with the lid closed.
It is desirable to test the input/output signal characteristics of the surface mount integrated circuit as the circuit interacts with the load board.
SUMMARY OF THE INVENTION
An apparatus in accordance with the present invention includes a load board and a device under test electrically interconnected with the load board. The apparatus also includes a pressure jig. The pressure jig includes a forcing unit and a structural member configured to fix a fixed portion of the forcing unit with respect to the load board. The forcing unit also has a pressure actuating component moveable with respect to the fixed portion of the forcing unit. The pressure actuating component contacts the device under test. In one embodiment, the apparatus includes at least one probe that contacts the terminal.
In accordance with the present invention, a testing method includes compressing a device under test towards a load board using a pressure jig. The method includes contacting at least one probe to at least one terminal of the device under test while pressing.
In accordance with the present invention, a method of fabricating includes providing a load board and electrically interconnecting a device under test with the load board. A fixed portion of a forcing unit is fixed with respect to the load board. A device under test is forced towards the load board using a pressure actuating component of the forcing unit. In one embodiment, at least one probe is electrically coupled to at least one terminal of the device under test such that the probe(s) carry a signal representing the voltage level of the terminal(s).
This apparatus and these methods have the advantage of providing a testing apparatus in which electrical interaction between lidded circuits and a load board may be monitored.
These and other objects, features and advantages of the present invention will be more readily apparent from the detailed description of the preferred embodiments set forth below taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4563636 (1986-06-01), Snook et al.
patent: 5446393 (1995-08-01), Schaefer
patent: 5489854 (1996-02-01), Buck
patent: 5528159 (1996-06-01), Charlton et al.
patent: 5552701 (1996-09-01), Veteran et al.
patent: 5731708 (1998-03-01), Shobhani
patent: 5949238 (1999-09-01), Marquis
Deb Anjan K
Metjahic Safet
Mosel Vitelic Inc.
Skjerven Morrill & MacPherson LLP
Steuber David E.
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