aos reliability report 1 aos semiconductor reliability report AOTF42S60 600v 42a a aa a mos tm power transistor rev. a alpha & omega semiconductor, inc www.aosmd.com
aos reliability report 2 this report applies for 600v 42a a aa a mos tm power transistor AOTF42S60. AOTF42S60 has been fabricated using the advanced a mos tm high voltage process that is designed to deliver high levels of performance and robustnes s in switching applications. by providing low r ds(on) , qg and e oss along with guaranteed avalanche capability these p arts can be adopted quickly into new and existing offline power supply designs. for halogen free add "l" suffix to part number: aottf42s60l commitment to excellence at quality & reliability! to achieve this vision, aos continuously strive for the excellence in design, manufacturing, reliabili ty and proactively response to the customers feedback . aos ensures that all the product quality and reliab ility exceed the customers expectation by constantly assessing any potential risk, identifyin g cause of the suspected failures, driving correcti ve actions and developing prevention plan within the c ommitted time through the continuously improvement. this aos product reliability report summarizes aos product reliability result. the published product reliability data combines the results from new prod uct qualification test plan and routine reliability program activities. accelerated environmental tests are performed on a specific sample size, and then followed by electrical test at end point. the released product will be categorized by the process family and be monitored on a quarterly basis for co ntinuously improving the product quality. table 1 lists the generic reliability qualification require ments and conditions: table 1: aos generic reliability qualification requ irements test item test condition time point sample size acc/reject htgb temp = 150 c , vgs=100% of vgsmax 168 / 500 hrs 1000 hrs 77 pcs / lot 0/1 htrb temp = 150 c , vds=80% of vdsmax 168 / 500 hrs 1000 hrs 77 pcs / lot 0/1 solder reflow precondition 168hr 85 c /85%rh + 3 cycle reflow @ 250 c (msl level 1) - the sum of pct ,tc and hast 0/1 hast 130 +/- 2 c , 85%rh, 33.3 psi, vgs = 10 0% of vgs max 100 hrs 55 pcs / lot 0/1 pressure pot 121 c , 29.7psi, 100%rh 96 hrs 77 pcs / lot 0/1 temperature cycle -65 c to 150 c, air to air, 250 / 500 cycles 77 pcs / lot 0/1 power cycle d tj = 125 c 4286 cycles 77 pcs / lot 0/1
aos reliability report 3 high temperature gate bias (htgb) & high temperatur e reverse bias (htrb) htgb burn-in stress is used to stress gate oxide at the elevated temperature environment hence any of the gate oxide integrity issue can be identified . htrb burn-in stress is used to verify junction degradation under the maximum operation temperature . through htgb & htrb b/i stress test, the device lif etime in field operation & long term device level reliability can be determined. fit rate is calculat ed by applying the arrhenius equation with the activation energy of 0.7ev and 60% of upper confide nce level at 55 deg c operating conditions. solder reflow precondition (pre-con) solder reflow precondition is the test that simulat es shipment and storage of package in under uncontrollable environment. precondition is the pre -requirement for the mechanical related reliability tests (such as temperature cycle, pressure pot and high acceleration stress test (hast). the routine of the test are: parts will be soaked in mo isture then bake in pressure pot, or being placed i nto 85% rh, 85 deg c environment for 168 hrs. then they will be run through a solder reflow oven with temperature at 250oc+/- 5oc. the test condition totally complies with msl level 1. pre-condition is a test that is detected package delamination, lifted bond wire issue. temperature cycling (tc) temperature cycling test is to evaluate the mechani cal integrity of the package and the interaction between the die and the package. this is an air to air test at temperature range from -65oc/150oc and stress duration is from 250 cycles to 500 cycle s. pressure pot (pct) pct test is the test that measures the ability of t he device withstand to moisture and contaminant environment. the test is done under enclosed chambe r with the condition 121oc 15+/- 1psig, 100%rh and stress duration is 96 hrs. high acceleration stress test (hast) high acceleration stress test is to stress the devi ces under high humidity, high pressure environment under dc bias condition. if ionic contamination inv olved, the corrosion from metal layer can be accelerated by the hast stress condition. power cycle the power cycle test is performed to determine that the ability of a device to withstand alternate exposures at high and low junction temperature extr emes with operating biases periodically applied and removed. it is intended to simulate worst case conditions encountered in typical application. the following tables summarize the qualification re sults based on the device/process families and the package types, respectively.
aos reliability report 4 table 2 reliability test and package test result: test item test condition time point total sample size number of failure htgb temp = 150 c , vgs=100% of vgsmax 168 / 500 hrs 1000 hrs 308 0 htrb temp = 150 c , vds=80% of vdsmax 168 / 500 hrs 1000 hrs 308 0 solder reflow precondition 168hr 85 c /85%rh + 3 cycle reflow @250 c (msl level 1) - 627 0 hast 130 +/- 2 c , 85%rh, 33.3 psi, vgs = 100% of vgs max 100 hrs 165 0 pressure pot 121 c , 29.7psi, 100%rh 96 hrs 231 0 temperature cycle -65 c to 150 c, air to air, 250 / 500 cycles 231 0 power cycle d tj=125 c 4286 cycles 231 0
aos reliability report 5 reliability evaluation: fit rate (per billion): 10 mttf = 11579 years the presentation of fit rate for product reliabilit y is restricted by the actual burn-in sample size o f the selected product. failure rate determination is bas ed on jedec standard jesd 85. fit means one failure per billion hours. failure rate (fit) = chi 2 x 10 9 / [ 2 (n) (h) (af) ] = 1.83 x 10 9 / [ 2 (2x2x77x168+2x2x77x1000) x (258) ] = 10 mttf = 10 9 / fit = 1.01 x 10 8 hrs = 11579 years chi2 = chi squared distribution, determined by the numbe r of failures and confidence interval n = total number of units from htrb and htgb tests h = duration of htrb/htgb testing af = acceleration factor from test to use conditions ( ea = 0.7ev and tuse = 55 c) acceleration factor [ af ] = exp [ea / k (1/tj u C 1/tj s] acceleration factor ratio list: 55 deg c 70 deg c 85 deg c 100 deg c 115 deg c 130 deg c 150 deg c af 258 87 32 13 5.64 2.59 1 tj s = stressed junction temperature in degree (kelvin), k = c+273.16 tj u =the use junction temperature in degree (kelvin), k = c+273.16 k = boltzmanns constant, 8.617164 x 10 -5 ev / k
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