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Figure 3: First-pass yield gains with auto contactor cleaning over
reactive off-line manual cleaning during high-volume production Figure 5: In situ cleaning sequence of a floating base socket using a flat cleaning unit with
testing of PA duplexer modules [8,9]. cleaning polymer.

Figure 4: Total test time savings when using in situ auto
contactor cleaning rather than reactive manual cleaning during Figure 6: In situ cleaning sequency of a floating base socket using a featured cleaning unit with
high-volume production testing of PA Duplexer Modules [8,9]. functional polymer balls.
[9]. Improvements for electrical data assistance systems (ADAS) content, a Eventually, these advanced sockets need
integrity can be inferred from the different class of test socket solutions are cleaning to remove debris from within the
higher first-pass yields and suggest that needed. Low inductance sockets with pin cavities. Disassembly of the floating
the passing die are certainly “known extremely short pins and reduced pitches base sockets requires substantially long
not bad.” In addition to the consistent are required for at-speed testing with downtime that reduces overall equipment
yield gains, the ACC-enabled test minimal signal distortion. The fine-pitch effectiveness (OEE) and often requires a
cells had significant test time savings IC packages often exhibit variable XYZ spares inventory. In situ cleaning with a
during first pass and retest for all three tolerances such that relying on mechanical cleaning device and the ACC functions is
devices (Figure 4). The total test time alignment within the socket is insufficient possible; however, there is an additional
improvements ranged from 20 minutes and can create unnecessarily high retest challenge because the compressed pins
to as much as 73 minutes [8,9]. Overall, rates. Poor coplanarity could damage both extend slightly or not at all above the floor
a combination of higher yields and the device and socket, especially if the level (Figure 5). Internal testing at the ITS
reduced total test times were obtained package is mis-seated when introduced and Center for Cleaning Materials Expertise
with all three devices and resulted in actuated against the contactors. (CCME) has shown that flat, unfeatured
a 10X return on investment for the A socket nest with a base that “floats” cleaning units do not provide sufficient
hardware upgrades [8]. Greater UPH on springs for a one-ball/one-pin cleaning unless the tips of the compressed
with higher yield values can reduce the alignment floor enables the device and pins extend at least 100µm above the floor
need for capital expenditures (CapEx) of solder balls to align centered above the to penetrate the cleaning polymer. To keep
additional test cell hardware. Depending probe tips. This type of socket is used pace with the cleaning demands, a new
upon the commercial value of the IC for most bumped devices such as BGA, class of surrogate was developed and built
packages, relatively small improvements chip-scale package (CSP) and wafer-level with “functional cleaning ball” features to
i n f i rst-pass yield and test time chip-scale package (WLCSP). Once the provide cleaning performance.
reductions will have immediate benefits balls are centered in the guide holes, the Functionalized structures provide
for net revenue. device can be introduced to the spring improvements and benefits that are not
probes without risk of ball or probe possible with unfeatured materials. The
Cleaning innovation for advanced damage. A floating base design also next generation of “turn-key” test contactor
sockets enables the use of shorter and low-travel cleaning (TCC) units are fabricated not
For applications that demand zero-defect pins by acting as a hard stop to protect only to match the package, but also to
manufacturing and high reliability, such the pins and DUTs from damage because emulate the ball grid array [11]. Rather
as the devices used for advanced driver- of over compression [10]. than a simple flat “unfeatured” surface,

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