What about the $4500 4-inch probe stations on eBay?

One of our customers asked me about certain 4 inch probe station being advertised for $4500 on eBay.

Below is an example of one of these stations.

We checked this machine based on its eBay listing & here are our findings & opinions:

Signal Integrity

With $650 overseas shipping cost this system appears super light to fit in a cardboard box not a crate. As most engineers will tell you, prober weight is very important for good measurement results. Heavier means a more stable environment for probing with low and no vibration affecting RF, DC or time domain data integrity and quality.

What is a 4" Probe Station?

We define a 4" prober as one with 4" chuck and 4" total travel in X and Y direction. In looking at this particular prober we were asked to evaluate, I noticed this machine comes with a 4" chuck, however travel is only 25mm in each direction- a little less than ONE INCH! This makes the prober a 1" prober, since travel is only 1". Why is this important?

It is because engineer is only able to travel 1" radius of the wafer. To probe outside of that radius he needs to manually move the wafer on the chuck.

Z-Axis (Up/Down) Movement

Another interesting discovery on this $4500 machine is that there is no provision for Z movement of the platen or the chuck. In other words neither the chuck nor the platen moves up and down. This means after probing one die you have to lift each of your probes up manually, move the chuck to the next die (assuming that die is within the 1" travel range) and place your individual probes down! The result wasted time couple with frustration to constantly place and align probe tips on pads! Probes' z-force variation result in inconsistent data quality as the engineer moves the probes manually from one die to the next.

All industrial probers come with at least a coarse Z-lift feature to allow moving between die and keeping the probe down force constant. Unfortunately this $4500 prober did not have that feature.

Microscopes

Finally, there was no provision for better microscope in case there is a need for finer geometry probing or simply taking and image of a die. A zoom microscope was all that is offered. In some models there was a camera port but magnification and image quality is very poor.

Conclusion

There is a lot to discuss-our conclusion is these machines are made to create an illusion of a prober. They are not a quality measurement solution for research & development or engineering. To summarize the machine is very cute, a small little guy:

A light weight machine Poor signal integrity

4" chuck with 1" travel It is really a 1" prober

No platen Z movement Lot of time wasted moving probes from one die to next

Zoom microscope Poor image quality hard to probe finer features

Camera Port But no camera

Only 2 Probes More probes more money price goes up

Limited platen space Only fits a very small number of probes

Incompatible Hard to mix and match accessories from other probe stations

Warranty Warranty unknown, and not clear if support and service is available