Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-08-31
2002-12-03
Karlsen, Ernest (Department: 2829)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S1540PB, C324S755090
Reexamination Certificate
active
06489794
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the testing of electronic modules, and more particularly to a high speed pass through test system and test method for testing electronic modules.
BACKGROUND OF THE INVENTION
Electronic modules, such as semiconductor memory modules, multi chip modules, semiconductor carriers, semiconductor packages, and microprocessors are routinely tested during manufacture. The modules include terminal contacts in electrical communication with the electronic devices contained on the modules. For performing various test procedures on the modules, temporary electrical connections are made to the terminal contacts.
One type of prior art electronic module
10
, which is illustrated in
FIGS. 1A and 1B
, includes a substrate
12
, and multiple semiconductor packages
16
mounted to the substrate
12
. The module
10
also includes a row of terminal contacts
14
on the substrate
12
in electrical communication with the integrated circuits contained on the semiconductor packages
16
. The terminal contacts
14
comprise generally planar, in-line metal pads located on opposing sides of the substrate
12
along a lateral edge
18
thereof. The substrate
12
typically comprises an electrically insulating material such as a glass filled plastic (FR-4), or a ceramic. In addition, the substrate
12
includes through openings
19
which facilitate indexing and handling by automated test equipment and carriers.
For testing the electronic module
10
, test systems have been developed and are commercially available from various manufacturers. These test systems are configured to make temporary electrical connections with the terminal contacts
14
on the module
10
. In addition, the test systems are configured to apply test signals through the terminal contacts
14
to the electronic devices on the module
10
, and then to analyze the response signals from the electronic devices. Often times these test systems merely test the gross functionality of the module
10
, as the semiconductor packages
16
on the module
10
have been previously individually tested and burned-in.
The test systems typically include test boards and test circuitry in electrical communication with the test boards. In addition, the test boards typically include interface boards having test contactors configured to physically and electrically engage the terminal contacts
14
on either side of the module
10
. In general, there are two types of test systems, which are sometimes referred to as “pass through test systems”, or “socket test systems”.
FIG. 1C
illustrates a pass through test system
11
PT having an interface board
13
PT, and test contactors
15
PT on the interface board
13
PT. The test contactors
15
PT are in electrical communication with test circuitry (not shown). In addition, the test contactors
15
PT are movable from an inactive (open) position in which the terminal contacts
14
on the module
10
are not engaged, to an active (closed) position in which the terminal contacts
14
on the module
10
are physically and electrically engaged.
As shown in
FIG. 1C
, with the test contactors
15
PT in an inactive (open) position, the module
10
can be indexed into a contactor area between the test contactors
15
PT, as indicated by arrow
17
PT. With the module
10
located in the contactor area, the test contactors
15
PT can be mechanically moved to the active (closed) position to physically and electrically engage the terminal contacts
14
. The pass through test contactors
15
PT are sometimes referred to as being “zero insertion force” (ZIF) contactors because temporary electrical connections can be made without an insertion force being placed on the module
10
.
FIG. 1D
illustrates a socket test system
11
S having an interface board
13
S, and test contactors
15
S on the interface board
13
S. In this case, the test contactors
15
S are normally in an active (closed) position, but are mechanically moved to an inactive (open) position as the module
10
is inserted from above, as indicated by arrow
17
S. When the module
10
is in place, the test contactors
15
S move back to the active (closed) position to physically and electrically engage the terminal contacts
10
. The socket test contactors
15
S are sometimes referred to as being “low insertion force” (LIF) contactors because an insertion force is exerted on the module
10
in making the temporary electrical connections with the test contactors
15
S.
One advantage of the pass through test system
11
PT (
FIG. 1C
) over the socket test system
11
S, is that no insertion forces are exerted on the module
10
to provide electrical engagement for testing. Accordingly, less physical stress is placed on the module
10
during testing with the pass through test system
11
PT. Also, as the number of terminal contacts
14
on the module
10
increases, the insertion forces exerted by the socket test system
11
S increase. The socket test system
11
S can therefore damage the module
10
, or the terminal contacts
14
on the module
10
, and can be more expensive to operate and maintain.
The present invention is directed to an improved pass through test system. In pass through test systems it is desirable to make temporary electrical connections with the terminal contacts
14
on the modules
10
that are reliable, and have low electrical resistance. This requires that the terminal contacts
14
be scrubbed, or alternately penetrated by the test contactors
15
PT, such that oxide layers and surface contaminants on the terminal contacts
14
do not adversely affect the temporary electrical connections. However, in scrubbing or penetrating the terminal contacts
14
, damage to the terminal contacts
14
and modules
10
must be minimized.
It is also advantageous in pass through test systems for the temporary electrical connections to provide electrical paths that are short in length to facilitate the application of high speed test signals, and to prevent capacitive coupling and the introduction of noise and spurious signals. Further, it is advantageous to make, and then break, the temporary electrical connections as quickly as possible, to facilitate a high throughput for the test procedure.
The pass through test system of the invention includes test contactors configured to make temporary electrical connections that are reliable, have low electrical resistance, and minimally damage terminal contacts on the modules. In addition, the test contactors are relatively inexpensive to make, provide a high throughput, and can be operated in a production environment with minimal maintenance.
SUMMARY OF THE INVENTION
In accordance with the present invention, a pass through test system and test method for testing electronic modules are provided. In illustrative embodiments, the test system is configured for testing electronic modules having planar, in-line terminal contacts substantially as previously described.
The test system includes test circuitry configured to generate test signals, and an interface board having interface contacts, and high speed conductors, in electrical communication with the test circuitry. The interface board can be mounted to an automated or manual test handler configured to transport, align, and hold the module on edge, generally parallel to the interface board.
The test system also includes test contactors configured to engage the terminal contacts on the component, and to simultaneously engage the interface contacts on the interface board. In illustrative embodiments, the test contactors comprise fret contacts configured to engage the terminal contacts with a zero insertion force (ZIF) on the module. An actuator mechanism moves the test contactors from an inactive (open) position wherein neither the terminal contacts on the module, nor the interface contacts on the interface board are engaged, to an active (closed) position wherein both the terminal contacts and the interface contacts are electrically engaged.
During electrical engagement of the terminal contacts, the interface contacts
Gratton Stephen A.
Karlsen Ernest
Micro)n Technology, Inc.
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