8 mm (0.31 inch) ultra mini seven segment displays reliability data description the following cumulative test results have been obtained from testing performed at agilent technologies in accordance with the latest revision of mil- std- HDSP-U0XX series hdsp-u1xx series hdsp-u2xx series hdsp-u3xx series hdsp-u4xx series hdsp-u5xx series 883. agilent technologies tests parts at the absolute maximum rated conditions recommended for the device. the actual perfor- mance you obtain from agilent parts depends on the electrical and environmental characteristics of your application but will probably be better than the performance outlined in table 1. table 1. life tests demonstrated performance stress test total units total failure rate test name conditions device hrs. tested failed mtbf (% /1k hours) operating life t a = 55 c 45,000 45 0 >45,000 <2.2 i f = rated current point typical performance failure rate prediction the failure rate of a semiconduc- tor device is determined by the junction temperature of the device. the relationship between ambient temperature and actual junction temperature is given by the following: t j ( c) = t a ( c) + q ja p avg where t a = ambient temperature in c q ja = thermal resistance of junction-to-ambient in c/watt p avg = average power dissipated in watts the estimated mtbf and failure rate at temperatures lower than the actual stress temperature can be determined by using an arrhenius model for temperature acceleration. results of such calculations are shown in table 2 using an activation energy of 0.43 ev (reference mil-hdbk-217). example of failure rate calculation assume a device operating 8 hours/ day, 5 days/week. the utilization fac- tor, given 168 hours/week is: (8 hours/day) x (5 days/week) / (168 hours/week) = 0.25 the point failure rate per year (8760 hours) at 55 c ambient temperature is: (<2.22% / 1k hours) x 0.25 x (8760 hours/year) = 4.86% per year similarly, 90% confidence level failure rate per year at 55 c ambient temperature is: (<5.11% / 1k hours) x 0.25 x (8760 hours/year) = 11.1% per year
table 2. failure rate prediction (i f = 30 ma dc) notes: 1. the point typical mtbf (which represents a 60% confidence level) is the total device hours divided by the number of failures . in the case of zero failures, one failure is assumed for this calculation. 2. the 90% confidence mtbf represents the minimum level of reliability performance which is expected from 90% of all samples. this confidence interval is based on the statistics of the distribution of failures. the assumed distribution of failu res is exponential. this particular distribution is commonly used in describing useful life failures. refer to mil-std-690b for details on this methodology. 3. a failure is any led which does not emit light. point typical performance performance [1] in time [2] in time (90% confidence) ambient junction failure rate failure rate temperature ( c) temperature ( c) mtbf [1] (%/1k hours) mtbf [2] (%/1k hours) 55 75 >45,000 <2.22 >20,000 <5.11 45 65 >69,000 <1.45 >30,000 <3.34 35 55 >108,000 <0.92 >47,000 <2.13 25 45 >174,000 <0.57 >76,000 <1.32 table 3. environmental tests test name mil-std-883c ref test conditions units tested units failed temperature 1010 -30 c to 90 c, 15 min. dwell, 5 min. 132 0 cycle transfer, 100 cycles solder heat 2003 260 c, 3 seconds 500 0 resistance solderability 2003 230 c, 10 seconds 23 0 resistance to mil-std-750 tca, 3 min. us bath, cotton 11 0 solvents [4] method 1022 swab, rub 3x note: 4. this test is for marking only, not for device functionality. test name mil-std-883c ref test conditions units tested units failed esd 3015.2 100 pf, 1.5 k w , 2000 volts 11 0 200 pf, 0 w , 200 volts 11 0 test name mil-std-883c ref test conditions units tested units failed vibration variable 2007 2 hrs for each x, y, z axis at 20 gs, 22 0 frequency 10 - 2000 hz; 20 min. sweep terminal strength 2004 condition a 0.5 lb. for 30 sec. 11 0 lead fatigue 2004 condition b bend 90 , 2x 11 0 physical 2016 check physical dimensions 23 0 dimensions table 5. electrical tests table 4. mechanical tests www.semiconductor.agilent.com data subject to change. copyright ? 1999 agilent technologies, inc. 5091-9422e (11/99)
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