MRF: What is the current management structure at Cascade, with you stepping out of the CEO position?
Strid: For a long time, I've wanted to switch back to a more technical role. We performed a classic and successful search for the right person to head up the company as CEO. Geoff Wild represents a wonderful combination of experience and complementary skill sets. I am just as busy as ever, but I sleep better at night now.
MRF: Does this give you a better opportunity on knowing where to steer the company technology-wise?
Strid: At a meeting like this MTT-S, I don't have to feel guilty about sitting in the technical sessions. I am here to absorb as much as possible. Moore's Law will run into trouble in the next decade. But in the near term, things are still changing exponentially with time. In spite of the weak economy, many companies have not slowed down their R & D efforts. For example, wireless operators want to constantly increase the data rates they can offer. Look at the interest in the 60-GHz band for high-data-rate communications. We don't even understand the bandwidth requirements of the next generation and what will be needed in terms of testing requirements.
MRF: Cascade has been in business for 25 years now. Did you and your cofounders, Dale Carlton and Reed Gleason, conceive of the company while working together at Tektronix?
Strid: Reed and I worked for the GaAs IC research group at Tektronix, which eventually became TriQuint Semiconductor. Dale came out of the oscilloscopes division. We published some initial RF probing results and some people thought what we were doing was a flash in the pan. But when we showed measurements for hundreds of devices on a wafer and people started asking us when we would productize our on-wafer probing capabilities. But Tek didn't really want to, since it was not a great product line fit for them, so we looked at each other and thought why don't we do this even if we just do it on weekends? We were very naive in the beginning, not realizing that the demand for these probes was much bigger than that, much more than we could meet by working only on weekends. The build-out of GaAs helped us a great deal, and then came the commercial adoption of GaAs for cellular telephones. The higher-frequency use of silicon in recent years has also driven the need for high-frequency on-wafer probing.
MRF: What was your first product?
Strid: The Model 42 probe station. It was pretty crude by today's standards, a manual 18-GHz probe station. We had relatively complete impedance standards to go with it. It was a breakthrough in productivity and measurement capability at the time, although applications have grown far more sophisticated today. Before the Model 42, you would bond up your chip and make measurements in a test fixture, and you were never really sure of the performance of the chip itself. Word quickly spread that the probe station indeed worked, and customers came back for a second or more, and it became accepted as a fundamental R & D measurement tool.
MRF: Did you have any relationships with test and measurement and/or semiconductor companies at the time of founding the company?
Strid: Having come from TriQuint, we had a good relationship with them. TriQuint was the first foundry to offer RF on-wafer test data and RF process-control-monitor (PCM) guarantees. We even shared some hospitality suites with TriQuint at trade shows in those early days. The main companion tool for our probes, of course, was the HP 8510 vector network analyzer (VNA), introduced in 1984 by Hewlett-Packard , so an obvious partnership with HP grew out of customers using our probe stations with their VNA. That partnership has been an extremely long-lived and productive partnership with HP/Agilent, and it is still going strong.
MRF: Have you received guidance from HP/Agilent over the years in what is needed from your end?
Strid: We get a great deal of feedback from them as well as from other testand- measurement companies. Some of it is insightful and useful, and some of it has to be calibrated like any other bit of market research. They've had some really useful parameters for us. Sometimes they've been off base on some things, and we have to measure everything that they give us. Sometimes the customers change their minds. Sometimes the markets don't develop as expected. But being on the leading edge in RF probing with companies like Agilent Technologies is fun and exciting, never dull.
MRF: Although you work closely with Agilent, your equipment can also work as easily with VNAs from other manufacturers, such as Rohde & Schwarz and Anritsu?
Strid: With the wide range of applications that need to be tested, we have to be able to respond to a customer's needs and their test system. Our Win- Cal software works with all of the available VNAs on the market, for example. Hardware wise, we have integrated with just about all of the measurement equipment that is out there at present. We try to keep up with all the probing requirements, and over temperature, with shielding, with automation, etc. Automation is probably the biggest change we've seen affecting our technology over the last decadetoday we offer production RF probes cards for use with automated test equipment (ATE) from Verigy, Teradyne, Roos, and Advantest. Packaging is either shrinking or going away. We are working with chip-scale packages, and customers want to maximize the yield of devices from a wafer. They want to test efficiently, using a probe card to test as many as eight or more devices at a time.
MRF: What was the most challenging requirement you've faced for an automated probe product?
Strid: For automated systems, the real issue is consistently making a lowresistance contact with a wafer, and doing that over millions of cycles in a production environment. We have studied the behavior of probe measurement quality over time, and the importance of the care and cleaning of measurement probes to ensure long-term reliability and measurement accuracy. A great deal of training is needed for all probe operators, no matter what the shift, in order to produce the best results. In the cost of ownership for our probes, the main breakthrough was in training.
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MRF: Was there anything new to show at the 2009 MTT-S?
Strid: We are rolling out 110-GHz engineering probes and 81-GHz production probe cards, which matches well with recent IC developments for 60-GHz HDMI and wireless LAN and 77-GHz automotive radar requirements.
MRF: Do you see a limit on device dimensions for which it might be difficult to develop a probe test solution?
Strid: We have made probes with 30- micron pitches, and we offer probes to 250 and 300 GHz, so we have been able to meet the demands for even very advanced devices. We are using semiconductor fabrication approaches to make our probes, so whatever can be done at the device level, we can also achieve in terms of the dimensions required for a probe to make contact with those devices. Our probes have to be photolithographically fabricated to reach the cost, electrical, and mechanical requirements at these higher frequencies.