aedr-8400-140 and aedr-8400-142 refective surface mount optical encoder reliability data sheet description the following cumulative test results have been obtained from testing performed at avago technologies malaysia in accordance with the latest revisions of jedec standard. avago tests parts at the absolute maximum rated condi - tions recommended for the device. the actual perfor - mance you obtain from avago parts depends on the electrical and environmental characteristics of your appli - cation but will probably be better than the performance outlined in table 1. failure rate prediction the failure rate of semiconductor devices is determined by the junction temperature of the device. the relation - ship between ambient 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 watt the estimated mttf and failure rate at temperatures lower than the actual stress temperature can be deter - mined by using an arrhenius model for temperature acceleration. results of such calculations are shown in the table below using an activation energy of 0.43ev (reference mil-hdbk-217). table 1. life tests demonstrated performance test name stress test conditions total device hours units tested total failed point typical performance mttf failure rate (% /1 k hours) high temperature operating life v cc =3.0v, t a =85 c, 1500hours 45,000 30 0 49,180 2.03 table 2. ambient temperature ( c) junction temperature ( c) point typical performance [1] in time performance in time [2] (90% confdence) mttf [1] failure rate (% / 1k hours) mttf [2] failure rate (% /1k hours) 85 89.7 49,180 2.03 19,520 5.12 75 79.7 72,640 1.38 28,840 3.47 65 69.7 109,800 0.91 43,580 2.29 55 59.7 170,000 0.59 67,500 1.48 45 49.7 270,700 0.37 107,400 0.93 35 39.7 443,800 0.23 176,200 0.57 25 29.7 751,900 0.13 298,500 0.34
notes: 1. the point typical mttf (which represents 60% confdence 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% confdence mttf represents the minimum level of reliability performance which is expected from 90% of all samples. this confdence interval is based on the statistics of the distribution of failures. the assumed distribution of failures is exponential. this particular distribution is commonly used in describing useful life failures. 3. failures are catastrophic or parametric. catastrophic failures are open, short, no logic output, no dynamic parameters while parametric failures are failures to meet an electrical characteristic as specifed in product catalog such as output voltage, duty or state errors. example of failure rate calculation assume a device operating 8 hours/day, 5 days/week. the utilization factor, 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: (0.59% / 1k hours) x 0.25 x (8760 hours/year) = 1.29% per year similarly, 90% confdence level failure rate per year at 55 c: (1.48% / 1k hours) x 0.25 x (8760 hours/year) = 3.24% per year table 3. environmental tests test name test conditions units tested units failed temperature cycle -40 c to 85 c, 15min dwell time, 5 min transfer, 1000 cycles 30 0 wet high temperature storage life t a =85 c, rh=85%, 1000 hours 30 0 table 4. electrical tests test name reference test conditions units tested units failed esd- human body model hbm-jesd22-a114d up to 4kv applied to all pins versus ground 9 0 esd- machine model MM-JESD22-A115-A up to 300v applied to all pins versus ground 9 0 table 5. mechanical and vibration shock test name test conditions units tested units failed mechanical shock 15,20,30g 11ms, 5 successive shocks in each direction of 3 perpendicular axes of units 15 pass vibration shock 15,25,30g 20-2khz, 10 cycles for ach g level. 15 pass for product information and a complete list of distributors, please go to our web site: www.avagotech.com avago, avago technologies, and the a logo are trademarks of avago technologies, limited in the united states and other countries. data subject to change. copyright ? 2007 avago technologies limited. all rights reserved. av02-0370en - april 27, 2007
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