Positive side support test assembly

Details Positive side support test assembly Positive side support test assembly

1999-12-02

2001-06-26

Karlsen, Ernest (Department: 2858)

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

C324S758010, C324S761010

Reexamination Certificate

active

06252413

ABSTRACT:

TECHNICAL FIELD
This invention relates generally to a method and apparatus for preventing lateral motion of a circuit card. More specifically, this invention relates to a method and apparatus for supporting a circuit card while testing through a connector on the circuit card.
BACKGROUND OF THE INVENTION
Circuit cards are often tested to ensure that the circuitry within the card and the components on the card are present and functional. If a circuit card includes a connector, it is desirable to also test the connector. If a circuit card is tested without testing the connector the circuit card may successfully pass the test while not having the connector installed or while having a non-functional connector installed.
Circuit cards can be tested using a test fixture
100
as shown in
FIG. 1
, for example. The test fixture
100
includes a first plate
110
having locating pins
112
,
114
. The locating pins
112
,
114
are located corresponding to the location of apertures in a circuit card
120
. The locating pins
112
,
114
are used to properly position the circuit card
120
. The circuit card
120
shown in
FIG. 1
is aligned in the test fixture
100
with the locating pins
112
,
114
protruding through the apertures of the circuit card
120
.
A probe block
130
including probes
116
is attached to the first plate
110
. A backer gate
140
includes probes
142
and posts
144
. The probes
142
,
116
contact the circuit card
120
to test components on the circuit card
120
or the circuitry of the circuit card
120
. Each probe
142
,
116
contacts a designated signal on the circuit card
120
. The posts
144
prevent the force of the probes
116
of the probe block
130
from bowing the circuit card
120
.
Circuit cards
120
often include connectors
150
mounted on the circuit cards
120
as shown in FIG.
1
. The probes
142
,
116
can be used to test components on or the circuitry of the circuit card
120
but will not test the connector
150
. To test the connector
150
, a side access unit
160
engages the connector
150
with side probes
162
. When the side probes
162
engage the connector
150
, the side probes assert a force in the “A” direction upon the connector
150
. Because the connector
150
is mounted on the circuit card
120
, the force in the “A” direction is applied indirectly to the circuit card
120
.
The number of side probes
162
needed to conduct a test increases as the number of connectors
150
on a circuit card
120
increases and as the number of pins on a connector
150
increases. The force in the “A” direction increases as the number of side probes
162
used to interconnect with the connector
150
increases.
The lateral motion of the circuit card
120
due to the force applied by the side probes
162
is opposed by the locating pins
112
,
114
which are used to position the circuit card
120
. As the number of side probes
162
increases, however, the force may become excessive and the locating pins
112
,
114
may bend or the apertures in the circuit card
120
may elongate, thus allowing the circuit card
120
to move laterally. This results in damaged locating pins
112
,
114
or a damaged circuit card
120
. If the probes
142
,
116
were in contact with the circuit card
120
when the side probes
162
caused the circuit card
120
to move laterally, the probes
142
,
116
may also be bent and damaged.
In addition to costs resulting from the damage to the locating pins
112
,
114
, to the probes
116
,
142
, and to the circuit card
120
, lateral movement of the circuit card
120
will result in the circuit card
120
being incorrectly positioned. The probes
116
,
142
are located to contact signals on the circuit card
120
. Successful contact with the signals on the circuit card
120
depends on the circuit card
120
being in a desired location. When the circuit card
120
is incorrectly positioned, the probes
116
,
142
may not contact their designated signals on the circuit card
120
. The probes
116
,
142
may contact an incorrect signal or no signal. This may result in a test failure of a circuit card
120
that is properly functional or result in test failures that are erroneously attributed to a misaligned circuit card
120
.
An edge block
170
as shown in
FIG. 1
may be used to offset the force in the “A” direction applied by the side probes
162
. The use of an edge block
170
is effective when the distance “B”, which is the length of the circuit card
120
that extends past the locating pin
114
, equals the distance between the locating pin
114
and the edge block
170
. Due to manufacturing tolerances, however, the distance “B” on circuit cards
120
is inconsistent. The distance “B” typically varies by ±0.51 mm (±20 mils).
If the distance “B” is less than the distance from the locating pin
114
to the edge block
170
, the force in the “A” direction will not be offset by the edge block
170
until the locating pins
112
,
114
have bent or the apertures in the circuit card
120
have elongated. If the distance “B” is greater than the distance from the locating pin
114
to the edge block
170
, the circuit card
120
will not fit on the first plate
110
.
To overcome the shortcomings of conventional circuit card testing, a new test apparatus is provided. An object of the present invention is to provide an apparatus for preventing the lateral movement of a circuit card. A related object is to provide an improved test apparatus for testing circuit cards by preventing lateral motion of the circuit card during testing. Another object of the present invention is to prevent lateral motion of a circuit card during testing when the location of the end of the circuit card is variable.
SUMMARY OF THE INVENTION
To achieve these and other objects, and in view of its purposes, the present invention provides an apparatus that opposes the lateral movement of a circuit card. Lateral movement of the circuit card is prevented by engaging an end of the circuit card.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.


REFERENCES:
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patent: 5500606 (1996-03-01), Holmes
patent: 5744948 (1998-04-01), Swart
patent: 5963027 (1999-10-01), Peters
patent: 6002263 (1999-12-01), Peters et al.

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