Page 36 - Chip Scale Review_November-December_2023-digital
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dependent. An exter nal loopback
channel simulation was conducted
based on different combinations
of probe length (Figure 9), cross-
sectional area (CSA) and rotation
angle. The aim is to find the optimal
insertion to cross-talk ratio (ICR)
and nominal channel eye width (EW)
and eye height (EH) for a 32GT/
s application as shown in Figure 10
Table 1: Probe dimension combinations. and Table 1.
Figure 10: Eye diagram of Merlion 6 at: a) (left) Eye height, and b) (right) Eye width.
Figure 10 shows the eye diagram
of Merlion 6 hybrid probes. This
new probe series provided the best
loopback @ 32GT/s meeting both
EH and EW requirements with the
best margi ns. From Table 2, we
can conclude that Merlion 6 hybrid
design is the best optimized selection
because it has the best combination
of probe intrinsic resonant, insertion
to cross-t al k rat io, and nom i nal
channel EW and EH. The new probe
head (Table 3) consists of th ree
Table 2: Summary of six different trials.
different probe designs to optimize
current-carrying capacity and high-
speed performance.
Figure 11 shows the Merlion 6
contact tests conducted on a bumped
wafer at room temperat u re. T he
hybrid probe solution shows stable
contact resistance, which will help
in minimizing probe burnout and
maximize the mean time between
failure (MTBF) of the probe card.
Probe head characteri zat ion:
test fixture. To validate the actual
Merlion 6 probe head f requency
performance in terms of S parameter
Table 3: Merlion 6 probe head variations.
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34 Chip Scale Review November • December • 2023 [ChipScaleReview.com]
