Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Reexamination Certificate
2001-03-15
2003-04-22
Cuneo, Kamand (Department: 2829)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
C324S755090, C324S756010
Reexamination Certificate
active
06552528
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to automatic test equipment used to test integrated circuit elements, and more particularly to interface hardware used in automatic test equipment to connect devices under test to a test head in order to perform the testing.
2. Description of the Related Art
Automatic test equipment (i.e., a tester) is generally used to test semiconductor devices and integrated circuit elements, such as memory or logic for manufacturing defects. A general representation of a tester is shown in FIG.
1
. As shown, a tester
1
has a tester body
10
, which is in communication with a test head
20
. The test head
20
is in communication with devices under test (DUTs)
60
via an interface
30
. The DUTs
60
are the various integrated circuit elements being tested. In this way, multiple DUTs
60
can be tested rapidly and simultaneously. Further, after a group of DUTs
60
are tested, a new group of DUTs
60
are introduced for testing using a handler
5
.
As shown in
FIGS. 2 and 3
, the DUTs
60
are arrayed on DUT boards
80
. The DUT boards
80
, also known as socket boards, device interface boards, and load boards, are on respective board spacers
40
, which rest on a spacing frame
50
. The board spacers
40
are hollowed in the center to allow cables
70
to be attached to the DUT boards
80
. Each DUT
60
is connected to a respective cable
70
through solder-lined through holes
83
in the DUT board
80
, with the actual connection being at solder point
82
. As such, each cable
70
is solder connected, individually, to the DUT board
80
.
For a conventional tester
1
, when a new type of DUT
60
is to be tested, the new DUT
60
is brought to the tester
1
via handler
5
and connected to a test socket (not shown), completing the electrical connection between the test head
20
and the new DUT
60
. The test is then performed. After completion of the test, the DUT
60
is then removed from the test socket via handler
5
, and a new DUT
60
of the same type is installed into the test socket using the handler
5
.
If a new type of DUT
60
is to be tested, the old DUT board
80
must be replaced and a new DUT board
80
inserted in its place. The new DUT board
80
will have different connection needs reflecting the new type of DUT
60
. As such, either a new interface assembly must be used, or the cables
70
must be resoldered at different solder points
82
. In either case, the cables
70
are custom fitted to different DUT boards
80
for each new type of DUT
60
to be tested. Further, where the cables
70
are resoldered, each change in DUT
60
type requires that the interface assembly, including the board spacer
40
, be partially or wholly disassembled, the cables
70
be soldered onto respective solder points
82
of the new DUT board
80
, and the interface be reassembled. On the other hand, where the entire interface assembly is replaced, large numbers of interface assemblies must be stored for each type of DUT
60
to be tested.
This use of solder connections is problematic since it is time consuming to attach the cables
70
to the solder points
82
of the DUT boards
80
. This problem is exacerbated as both the density and/or number of DUTs
60
increases. For instance, modern testers can accommodate up to 128 DUTs
60
per test head
20
, with changes in the types of DUTs
60
being made multiple times per week, or even per day. As such, the requirement that the interface be disassembled and reassembled, and the custom soldering to connect the cables
70
to the different types of DUT boards
80
can require significant time and expense to perform for each change in the type of DUT
60
to be tested, and also significantly increases the amount of time required to test the DUT
60
s.
As shown in
FIG. 4A
, one solution to the limitations of solder connection has been to utilize spring loaded pogos
100
, such as the pogo pin produced by Everett Charles, which rest on respective pogo boards
110
. The pogos
100
include an internal spring that allows the top half of the pin
100
to be biased against a pad
90
on the DUT board
80
, thus forming a communication pathway to a respective DUT
60
. Using this system, when a new type of DUT
60
is to be tested, the cables
70
do not have to be soldered to the DUT board
80
. Instead, the cables
70
remain soldered to the pogo boards
110
, and the new DUT board
80
is placed on the pogo board
110
such that the pins
100
are biased against respective pads
90
to form the communication pathways. As such, the entire interface does not have to be changed.
However, this solution also is problematic as the number and density of DUTs
60
being tested increases. As the density of DUTs
60
being tested increases, smaller and smaller pogos
100
must be used in order to fit into the space provided under the DUT board
80
. As the pogos
100
get smaller, they become more delicate and difficult to work with. Further, as pogos
100
get smaller, their stroke (i.e., the distance that the tip of the pin
100
can travel vertically in order to bias against pad
90
) decreases, which means that the DUT board
80
and the pogo boards
110
must be made highly planar to ensure a connection at all pads
90
. This increases the production cost for the pogo boards
110
and the DUT boards
80
. In addition, pogos
100
are themselves expensive to use. As such, pogos
100
do not present an ideal alternative to solder connection as the density and/or number of DUTs
60
increases.
Where the DUT
60
is a logic element
65
, it is known to perform lower parallelism testing using plugs
160
as shown in
FIGS. 4B and 4C
. For logic elements, the cables
70
are soldered into daughter boards within plugs
160
. The plugs
160
, such as the Micopax plug produced by FCI, are held by a plug holder
180
, and are connected to respective receptacles
170
. The receptacles
170
are connected to a logic board
150
. In this way, instead of directly solder-connecting the cables
70
to the logic board
150
, the plugs
160
are received by receptacles
170
located on the logic board
150
. Not all of the plugs
160
are used for each type of logic element
65
tested.
However, this configuration is known for use in lower-parallelism testing of logic elements
65
, and requires the use of eight or more plugs
160
per logic board
150
. Such a configuration is unsuitable for high-density, high-parallelism testing of DUTs, especially where the DUT is a smaller device such as a memory device. In order to test these devices, the DUT boards are smaller, which prevents the use of numerous plugs
160
. Further, the handlers
5
that move the memory devices, such as the Advantest M65XX and M67XX series handlers, use spacing frames having a pitch that does not allow the use of a large number of plugs
160
in order to test these devices. Thus, for high-parallelism testing of memory devices (i.e., simultaneous testing of 32 or more devices), conventional plug arrangements were not possible.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a connection system between devices under test and a test head that provides a secure modular connection to the devices under test for high data rates without causing degradation in signal quality.
It is a further object of the invention to provide a high density, scalable connection system between devices under test and a test head.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve these and other objects, an embodiment of the present invention uses an interface between a device under test (DUT) and cables, including a first board having an array of first connectors, each first connector connected to a respective cable, and a second board holding the DUT and having second connectors, each second connector being connected to the
Advantest Corporation
Cuneo Kamand
Nguyen Tung Y.
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