Quartzdyne Pressure Transducers

Digital Hybrid Prototypes Now Available

Quartzdyne is now offering beta transducers that incorporate a hybrid version of our I²C digital circuit. Our I²C-compatible digital circuit is a 2-wire serial interface that provides 32-bit counts for pressure and temperature, eliminating the complicated task of frequency counting. The hybrid version offers improved long-term reliability and higher temperature operation than the standard 150°C-rated surface-mount version. In parallel with offering beta digital hybrids to customers, we've placed digital hybrids in each of our 180°C, 200°C, and 225°C life-cycle tests.

We use the same components in both the surface-mount and hybrid versions. The hybrid offers better reliability since the active die are free from commercial plastic packages. The silicon die are adhered to a ceramic substrate and wire-bonded to make electrical connections. The bulk silicon FPGA die limits the operating temperature of the digital hybrid to 177°C [350°F]. Above 177°C, increasing leakage currents retard gate-switching until eventual shutdown, but temperature excursions to 200°C will not damage the hybrid.

Our frequency-output hybrid operates at 225°C because it incorporates discrete, large-geometry transistors designed for high frequency (i.e., cell phone) applications. Small geometries in standard (commercial) silicon devices place transistor wells "too close together"--leading to high leakage currents above 200°C. We are therefore pursuing a 250°C silicon-on-insulator (SOI) FPGA; this opportunity will be several years in the future.

We invite interested customers to contact us about receiving a digital hybrid prototype (177°C). Electrical specifications of the digital circuit are located on our website at:

Circuit Reliability Statistics--Now Over 5 Million Test Hours!

Quartzdyne currently accumulates over one million destructive test hours on circuits every year. As of January 2004, we've tested more than 1000 circuits and accumulated over 5 million test hours in our life-cycle tests! That represents an enormous investment, but it's well worth the confidence it builds with our customers. Milton Watts, our Vice President of Engineering, is presenting a paper at the upcoming HITEN conference in Santa Fe, NM on May 18, 2004. For those attending the conference, Milton's paper provides some "statistically significant" results on electronics design and reliability.

Reliability Update (Field Returns)

Since 1994, we have maintained a database containing information on transducer returns. We record the specific failure mode and elapsed time since shipment for each transducer. Since in-house component screening, design qualification, long-term product testing, and transducer calibration typically identify the major failure modes in our transducers, field returns rarely reveal new or unexpected failures. Every year, we analyze the database for trends, and share the results openly on our webpage. This report describes the general design of a Quartzdyne^® Pressure Transducer, and provides the reliability statistics and common failure modes for each of the major components, based on field-failure returns.

It is rare to find a company that publicizes their failures (albeit our failure rates are low.) However, we consider this an important part of continuous improvement. We hope that our customers appreciate our candor and honesty, as well as our ongoing efforts to improve the reliability of our products. This year's report highlights the continued reliability of Quartzdyne pressure crystals (less than 1% failure rates since 2001) and continued improvement of the hybrid circuit robustness. You'll find this year's report at the following link: http://www.quartzdyne.com/pdfs/reliability.pdf.

We now EB weld all of our pressure housings in-house. In compliance with the AMS 2681 specifications for EB welding, we've developed appropriate PQR (Procedure Qualification Records) and WPS (Weld Procedure Schedules) to make full penetration EB welds on our pressure-bearing joints in conformance with AMS 2681. All production EB welds are pressure checked at 10% above the maximum calibration pressure; we also routinely test non production EBW samples to 35,000 psi and 225°C without problem.