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TAP TIMES October 2022
TM
Volume 13, Number 9
Test, Assembly & Packaging TIMES
Adapting contactor probes for high-power QFN devices
T he global power semicon- At the board and system level, large FPGA
ductor market in 2020 was
ICs, SOCs, GPUs and CPUs may demand
valued at $37.9 billion and
hundreds of amps of continuous current
is expected to reach $47.19
and instantaneous switching currents that
billion by 2027 with a
3.17% CAGR, Statista fore-
casts. are 3-4X the continuous loads.
The system-level power delivery circuits
are quite sophisticated, with phase, tim-
Ron Lesnikoski, Signal Integrity Inc.
ing, control feedback and onboard micro
controllers are all integrated to manage
Power semiconductors perform the same the output switching of very high cur-
tasks as other semiconductors, only on a rent FET front ends. (A block diagram of
much larger DC scale. These high-perfor- a power output stage in fi gure 1 below is
mance components are capable of han- readily available from public sources and
dling extremely high electrical currents, shows the FET output path clearly).
high voltages, and dissipate hundreds of
watts, making their test a critical function.
They are used to rectify, switch, regulate,
and convert DC and AC power signals.
These are typically used for industrial con-
trol, automotive, solar, EV, network serv-
ers and enterprise storage power manage-
ment.
This diagram shows the Power MOSFET pair sourcing and sinking
Test current between the Vin and SW output. A search for a typical
part returns a package in a plastic 5mmx5mm PQFN with pin
socket pads at 0.5mm pitch. And center metal pads for GND. Typically,
for power the package has multiple pads for Vin inputs and SW outputs, for
this example, Vin has 4pins, and the SW output has 8 pins on a
controlloer 32L package.
with IGBT
front-end Switching current transient
transistor In our example, the switching current
pads. transient is 60A for 1µsec and the con-
tinuous current which is demanded by
the application is 10A. This device when
(Signal mounted on the PC board is soldered on
Integrity) large copper pads.
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