Report describes tests used to determine minimum time for capacitors to fail due to overvoltage and maximum amount of overvoltage that capacitors could sustain without permanent damage

Castle, K. D.

Zill, J. A.

English

NASA Technical Reports Server

- ===.October 1975	 B75-10274 
NASA TECH BRIEF 
Lyndon B. Johnson Space Center 
NASA Tech Briefs announce new technology derived from the US: space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Response of Tantalum Capacitors to Fast Transient Overvoltages 
S
A study has been conducted to characterize the 
response of tntalum capacitors to fast transient 
overvoltages. The results have been published in a 
report (see note 1). 
The report describes tests that were used to 
determine: (a) the absolute minimum time for the 
capacitors to fail due to overvoltage and (b) the 
maximum amount of overvoltage that the capacitors 
could sustain for 100 jAs without permanent damage. 
The tests were conducted by using a specialized 
commercially-available high-voltage tester, a 50-MHz 
oscilloscope with a camera, and a 50-Vdc power 
supply. Two groups of capacitors were tested: one 
group included 18-HF, 50-V dry tantalum capacitors; 
the other included 6.8-HF, 50-V wet tantalum 
capacitors. The test results were obtained by 
analyzing photographs of waveforms taken from the 
oscilloscope display. 
The results show that when the dry tantalum 
capacitors are overstressed with forward voltage 
polarity, they fail at 190 percent of the rated voltage in 
100 is. The reverse voltage limit and the time to 
failure are equal to 100 percent of the forward rated 
voltage and 100 jAs, respectively. 
In contrast, the forward voltage tolerance of the wet 
tantalum capacitors is 300 percent of the rated voltage 
for approximately 140 ps. The reverse voltage limits 
are 100 percent of the forward voltage ratings and 
occur in 250 is. 
The shortest possible time to failure observed was 
25 ps. This was obtained by using a very high current 
generator output of 750 A at 56 V. Shorter failure 
times were not anticipated due to the kinetics of the 
failure mechanism within the capacitors.
Notes: 
1. Further information is available in the following 
report: 
NASA TM-X-58152 (N75-14030), Tantalum Ca-
pacitor Behavior Under Fast Transient Over-
voltages 
Copies of this report may be obtained at cost from: 
Technology Application Center 
University of New Mexico 
Albuquerque, New Mexico 87131 
Telephone: 505-277-3622 
Reference: B75-10274 
2. Tatalum capacitors are also discussed in NASA 
Tech Brief B74-10294. 
3. Specific technical questions may be directed to: 
Technology Utilization Officer 
Johnson Space Center 
Code AT3 
Houston, Texas 77058 
Reference: B75-10274 
Patent status: 
NASA has decided not to apply for a patent. 
Source: J. A. Zill and K. D. Castle 
(MSC-14822) 
I,
'	 J 
ot 
Category: 01 (Electronics - Components 
and Circuitry) 
This document was prepared under the sponsorship of the National
	
Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	
information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19750000274 2020-03-19T20:14:16+00:00Z


Response of tantalum capacitors to fast transient overvoltages

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