Test Equipment
Load Boards / Interface Boards
A
load board,
interface board,
or DUT board is a circuit board designed to serve as an
'interface'
circuit
between the automatic test equipment
(ATE)
and the device under test
(DUT).
Load boards
(see Fig. 1) contain the necessary components to: 1) set
up the DUT for correct testing by the ATE; 2) route
the test and response signals between the DUT and the ATE; and 3)
provide additional test capabilities that the ATE may not be able to
provide. There are
also load boards designed for the purpose of testing or calibrating the
ATE itself (see Fig. 2).

Fig. 1.
Photos of ATE Interface Boards or Load Boards
An
ideal load board introduces no distortion, noise, delays, nor errors to
the testing process of the DUT. This means that an ideal load board is
one that doesn't seem to exist at all, i.e., as if the DUT were directly
connected to the ATE. To come out with a load board as close as
possible to this ideal one is the challenge to every engineer who
designs load boards.
Load
boards are often
customized
to a specific device or group of devices. As such, complete,
ready-to-use load boards are not normally available off-the-shelf.
The usual way to acquire a load board for a new product is to have it
designed
and
fabricated.
Thus, most test engineering groups have a certain level of expertise in
designing and fabricating a load board.
A load board consists of a
PCB with a test socket or handler interface as well as a variety of
components (IC's, resistors, capacitors, inductors, relays, connectors,
etc.) that make up the load board's test circuits. The typical laminate
for the load board PCB is the
FR4
(Flame Retardant 4 fiber glass). The number of layers of a load board
PCB also varies, depending on the complexity of the design. Some load
boards for complex devices may even have more than 20 layers.
<Proceed to Page 2 - Designing Load Boards>
See also:
Test
Accessories;
Test Equipment;
Electrical Testing;
Semiconductor
Manufacturing
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