M39003 VAISH [Vaishali Semiconductor], M39003 Datasheet - Page 17

• Manufacturer Part Number: M39003
• Manufacturer: VAISH [Vaishali Semiconductor]

www.vishay.com
17
M39003/01/03/06/09
Vishay Sprague
WEIBULL DISTRIBUTION METHOD FOR
DETERMINING FAILURE RATE, MIL-C-39003 ( Cont’d)
If no failures occur, the lot can be re-started at a higher stress
level only once. If no failures occur at the higher stress level,
the lot is not suitable for Weibull analysis.
After a minimum of 40 hours, the failure count is again taken.
If no further failures occur, one is added to the count. Failure
rate is calculated by the following:
ACTUAL WEIBULL TEST ANALYSIS FOR THE VISHAY SPRAGUE
t0 15 min
Z(t) = [-ß 1n (1-P2)105]/t2A.F.
2 hrs £ t1 £ 10 hrs
For technical questions, contact: [e-mail]
Military MIL-C-39003 Qualified, Syles CSR13, 21, 23,
Solid-Electrolyte TANTALEX® Capacitors,
40 hrs
Where
The failure rate can be calculated from the previous formula
as follows:
33
Z(t) = Failure Rate
ß = Weibull shape parameter (slope of the line
between t1 & t2 graphed on paper with a 1n (t)
abscissa and 1n 1n (1/(1-P)) ordinate
P = Ratio of failures to units on test at stop time
t2 = Number of hours on test
A.F. = Acceleration Factor
Z(t) = [-ß 1n (1-P)105]/t A.F.
Z(t) = [-0.2119 1n (1-0.0326)105]/40(17356)
Z(t) = [-0.2119 (-0.0331) 105]/6.9424 (105)
Z(t) = [0.0070/6.9424]
Z(t) = 0.0010 %/1000 hrs
®
EQUIPMENT
Document Number: 40018
Revision: 08-Feb-06