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the yield drops below the specification type of automated contactor cleaning [7]. These surrogate packages are
limit). Both procedures are time intensive (ACC) process using on-board functions turn-key units (shown in Figure 2),
and result in variable yields, as well and hardware for minimal idle time. fabricated to match the XYZ dimensions
as increases in the overall test time for Unlike the manual cleaning operations, of the package and emulate the device
reduced throughput [5]. The amount the ACC functions can be performed package type (ball grid array [BGA],
of downtime increases substantially during device testing, at temperature, package on package [PoP], quad-flat no-
when the handler must be brought to and on-demand to maintain the highest leads [QFN], quad-flat package [QFP],
room temperature and returned to test throughput [6]. The automated cleaning leaded, leadless, etc.). Two basic types of
temperature after socket cleaning. execution is performed with engineered cleaning materials are available for the
Practically all roadmap handlers built test contactor cleaning (TCC) devices applications: 1) abrasive polymer-based
within the past five years implement some that match the device under test (DUT) materials, or 2) tacky abrasive materials
[5,7]. Both material types are configured
to collect the contamination from the
contactor, remove debris accumulated
within the bed of the socket, and polish
the contactor surface to recover electrical
performance. Using a preprogrammed
cleaning recipe, the devices are regularly
cycled through a handler with minimal
downtime. Depending on the application
requirements, the cleaning efficiency of
these materials can be optimized across a
wide temperature range [7].
THE BURN-IN WITH Case study: high-volume

TEST COMPANY manufacturing
In this collaborative project, the
benefits of ACC were characterized in a
high-volume application [8,9]. Multiple
production test cells were selected,
each with throughputs of approximately
750K to one million devices per month.
The worldwide leader in test with burn-in Four of the test cells were upgraded and
systems, Micro Control offers solutions for enabled with the ACC function; and two
high-power burn-in test applications of the test cells used a reactive manual
requiring individual temperature control and cleaning strategy. Because of the units
logic/ memory burn-in test applications for per hour (UPH) requirements of this
lower power devices. application, unscheduled downtime
associated with manual cleaning
operations would have significant
impact on the throughput and the total
Micro Control Company’s burn-in systems test time. Multiple lots of three different
feature a pattern zone per slot, multiple
temperature zones and independent leadless multiplexer devices (devices A,
temperature control per DUT. With up to B, and C) were split across the six test
64 M of vector memory behind all 128 cells. During the evaluation period, the
independent I/O channels, Micro Control production performance results of the
systems can handle many different test cells were closely monitored. The
functional tests.
functional tests. first-pass yield, retest yield, and test
time metrics were tracked for the three
devices across multiple split lots.
Upon completion of the evaluation
Have other needs? period, the test cells using the in situ
Micro Control Company provides
burn-in boards, prescreen stations, ACC cleaning function averaged first-
carts, and continuity testers. pass yield gains of approximately 1.11%,
0.77%, and 3.23% (Figure 3) for the
three devices [8,9]. In all instances, the
re-test, or recovery yields, on the ACC-
enabled test cells were consistently
7956 Main Street NE | Minneapolis, MN 55432 | 800.328.9923 | microcontrol.com lower, indicating a high level of test
effectiveness during the first-pass test

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