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Development of High Temperature Capacitor Technology and Manufacturing Capability
Project Number
Last Reviewed Dated

The goal of this project is to design and conduct controlled experiments to systematically optimize manufacturing and testing processes for fluorene isophthalate terephalate (also known as fluorene polyester or FPE) capacitors to encourage the commercial availability of a reliable and affordable supply. Film casting, film metallization, and final capacitor assembly processes will be optimized.


Hamilton Sundstrand, Rockford, IL 61125
Brady Corporation, Milwaukee, WI 53201
Dearborn Electronics, Inc., Longwood, FL 32750
SteinerFilm, Williamstown, MA 01267


Capacitors are an important component of downhole logging-while-drilling (LWD) and measurement-while-drilling (MWD) electronics. There is a need to develop and enhance the electronics industry's capabilities to produce temperature resistant capacitors that will support the use of these tools at greater depths and under more hostile conditions.

FPE technology is currently used to provide high-temperature (HT) capacitors utilized in the aerospace industry. This industry has been using metalized film capacitors for power conditioning, filtering, and energy storage applications for decades. Metalized film capacitors have the ability to “clear” small defects, exhibit high reliability, and tend to fail in a controlled and manageable fashion at the end of a long and useful life. The alternatives have weaknesses: multilayer ceramic (MLC) capacitors have violent failure modes and are highly susceptible to vibration and thermal cycling environments, while electrolytic capacitors have problems with “dry-out”, have short lives, and exhibit low reliability at elevated temperatures. For these reasons, the aerospace industry has focused on metalized film capacitors as the most viable high-temperature capacitor solution.

Unfortunately, FPE capacitors have been manufactured on a “one-of-a-kind-special-order” basis and the industry suffers from poor manufacturing yields at all stages of the manufacturing process. Widespread use of FPE film capacitors (particularly for oil field drilling services applications) will not be practical until they can be efficiently mass-produced in a financially self-sustaining manner. Evidence of manufacturing feasibility will be required before Hamilton Sundstrand and downhole drilling equipment suppliers will be able to design and produce robust, saleable, distributable, and serviceable FPE capacitors.

This research project builds on the strong partnerships currently in place among Ferrania (FPE resin manufacturing), Brady Corporation (film casting), SteinerFilm (film metallization), Dearborn Electronics (capacitor manufacturing), and Hamilton Sundstrand (applications and systems expertise) to develop an optimized production process for HT FPE capacitors. These partners will collaborate on the systematic design of experiments involving four production-sized batches of FPE capacitors.


Successful execution of this effort will result in commercially available, reliable, and affordable 250 °C rated capacitors. HT capacitors could be extensively used in downhole drill motor drives and downhole MWD communication devices provided a reliable and affordable supply is available to the petroleum industry. The increased temperature capability of HT capacitors will minimize the cooling requirements in line-replaceable units (LRUs), allowing other components to utilize valuable heat sink areas. Alternatively, size and weight can be reduced in LRUs by decreasing the heat sink mass. In addition, increased thermal capability will greatly increase the reliability of capacitors. By providing a large thermal de-rating, a capacitor rated at 250 °C will be much more reliable at 150 °C operating conditions. The root-mean-square (RMS) current handling capability of HT capacitors will not be thermally limited when a 250 °C capacitor is used in a 150 °C application in place of conventional low-temperature capacitors.

This project is primarily focused on commercializing cost-effective, reliable, FPE capacitors for downhole applications. This in turn will reduce the drilling costs for developing deep gas resources, improving the likelihood that larger volumes of such resources can fill domestic consumer demand for natural gas at a reasonable price.

Accomplishments (most recent listed first)
  • Through the DOE/NETL Development of High Temperature Capacitor Technology and Manufacturing Capability Program, the manufacturing processes of high temperature FPE film capacitors have been drastically improved. The FPE film production metallization and winding yield has increased to over 82% from 70%, and the voltage breakdown strength of the wound capacitors has increased 270% to 189 V/µm.
  • Using capacitors that passed both the acceptance and life tests as a standard, the project team was able to achieve film winding yields of 100%, clearly establishing winding conditions for the FPE capacitor..
  • Dearborn Electronics is actively marketing FPE capacitors to its wide industrial, aerospace and petrochemical customers (FPE capacitor Spec sheet can be found in the Final Technical Report available below under “Additional Information.
  • Batch 3 and 4 FPE capacitors showed positive results at 200 and 250°C, however high dissipation factor remains to be an issue.
  • Dearborn has completed initial, high-temperature, and post high-temperature testing for the second part of capacitor batches 3 & 4. Initial results indicated higher dissipation factor (DF) results relative to the first part of capacitor batches 3 & 4. The group tested to 250°C failed the DC leakage testing. The units with high DF will still be used in the packaging study, and electrically good FPE sections from PART II will then be used in the final test stage—building/assembling and 250 hour life testing of the fully assembled capacitor.
  • The End Spray issue has been resolved allowing for additional product testing.
  • Batch 3 and 4 film casting and metallization have been completed.
  • The FPE formula and handling has been optimized throughout the batch 1 manufacturing process based on experimentation and batch 1 capacitor performance results. All six (6) rolls of batch 2 FPE film have been manufactured and metalized, and capacitors have been constructed and tested resulting in a significant improvement in capacitor yields and electrical performance.
  • Batch 2 capacitors have shown significant improvements in yields and both electrical and thermal performance relative to batch 1 capacitors.
  • With the completion of batch 1 and 2 casting, metalizing, and capacitor production and testing, every step of the FPE capacitor manufacturing process has undergone a complete research and optimization stage.
  • A Research Management Plan and Technology Status Assessment were completed. Hamilton Sundstrand, Brady Corporation, SteinerFilm, and Dearborn Electronics have completed work on the first two of four production-sized batches of capacitors, and work on the third batch has begun. Every step of the process/supply chain has been optimized based on the results gathered from the first two batches. Brady Corporation has successfully manufactured 18 rolls of FPE film. SteinerFilm has metalized these rolls and provided them to Dearborn to manufacture the first two batches of capacitors. Brady and SteinerFilm have improved the FPE formula and machine handling, respectively. Capacitors were wound and tested at Dearborn with some devices attaining breakdown voltages of 1000 V and temperatures of 200°C.
Current Status

(September 2011)
The project has been completed. The final report is available below under "Additional Information".

Project Start
Project End
DOE Contribution


Performer Contribution


Contact Information

NETL – William Fincham ( or 304-285-4268)
Hamilton Sundstrand – Jeff Nelson ( or 815-226-6141)

Additional Information

Final Project Report [PDF-2.85MB] August, 2011

Technology Status Assessment [PDF-168KB]