Cascade Microtech P800-S - Manual (Page 5)

PN 151-853-A www.cascademicrotech.com Pyramid Probe Card: P800-S Online Cleaning• 5
Cleaning Pyramid Probe cards by contacting a cleaning substrate takes multiple touchdowns to achieve good results. A
ratio of 2.5 probing cycles to the number of cleaning cycles is expected. Experiment to find the cleaning count that works
best in your environment. Eighty cleaning contacts for 200 touchdowns is a good number to start.
Online Cleaning Frequency – Yield vs. Wear
Each time a probe card is cleaned abrasively, a small amount of probe tip material may be removed in addition to the
contaminant. When developing a cleaning strategy for probe cards, a trade-off is made between the lifetime of the probe
card and the test yield. Yield suffers if the probing-to-cleaning ratio is set too high. Alternatively, probe card lifetime and test
equipment utilization suffer if the probing-to-cleaning ratio is set too low. When developing the cleaning strategy, the
objective is to determine a probing-to-cleaning ratio low enough to minimize probe tip wear, but high enough to maximize
yield.
Figure 5. Probing-to-cleaning touchdown ratio.
Overtravel
If all the tips are in contact, increasing cleaning overtravel on Pyramid Probe tips does not increase the foreign material
removal rate. In fact, higher cleaning overtravel may accelerate the accumulation of particles from the cleaning substrate.
The tips on a Pyramid Probe range from 20-55 µm tall. The foam on abrasive coated foams is soft, enabling the probe tips
to push into it relatively easily. Therefore, increasing overtravel values far beyond the tip length does not increase the
cleaning action because the tips are buried and the probe face is simply compressing the foam.
It is best to set the overtravel high enough to ensure that all tips contact the film, but low enough to minimize particle
generation from the film. Typical cleaning overtravel used in the Cascade Microtech factory environment is 35 to 75 μm.
Cleaning Recipe, Initial Settings
Experiments were performed in the factory on solder covered wafers to establish a cleaning recipe to use as a starting
point for customers probing solder balls with P800-S Pyramid Probes. Contact resistance was monitored while the number
of cleaning touches was varied. Cleaning cycles were made after every 200 contact resistance measurements. A ratio of
probing contacts to cleaning contacts was calculated for each recipe. The tested ratios were 1:1, 2.5:1, 5:1, and 10:1. The
results showed that the highest ratio of probing to cleaning that maintained less than 0.5 ohms increase in contact
resistance was 2.5:1; or 80 cleaning cycles for every 200 measurements. A cleaning recipe can be created using the
process described in this document, or by starting with these values and refining them based on yield.
Die between cleaning cycles 200
Cleaning TD per cycle 80
Cleaning overtravel: 50 µm
Cleaning material MIPOX WA6000-SWE
Online Cleaning Instructions