1 aos semiconductor product reliability report AO4800/ AO4800l , rev a plastic encapsulated device alpha & omega semiconductor, inc 495 mercury drive sunnyvale, ca 94085 u.s. tel: (408) 830 - 9742 www.aosmd.com jul 14 , 2005
2 this aos product reliability report summarizes the qualification result for AO4800 . accelerated environmental tests are performed on a specific sample size, and then followed by electrical test at end point. review of final electrical test result confirms that ao4 800 passes aos quality and reliability requirements. the released product will be categorized by the process family and be monitored on a quarterly basis for continuously improving the product quality. table of contents: i. product description ii. package and d ie information iii. environmental stress test summary and result iv. reliability evaluation v. quality assurance information i. product description: the AO4800 use s advanced trench technology to provide excellent r ds(on ) and low gate charge. the two mosfets mak e a compact and efficient switch and synchronous rectifier combination for use in buck converters. AO4800l (green product ) is offered in a lead - free package. absolute maximum ratings t a =25c unless otherwise noted parameter symbol maximum units drain - source voltage v ds 30 v gate - source voltage v gs 12 v t a =25c 6.9 continuous drain current g t a =70c i d 5.8 pulsed drain current c i dm 40 a t a =25c 2 power dissipation b t a =70c p d 1. 44 w junction and storage temperature range t j , t stg - 55 to 150 c thermal characteristics parameter symbol typ max units maximum junction - to - ambient t = 10s 48 62.5 c/w maximum junction - to - ambient steady - state r q ja 74 110 c/w maximum junction - to - lead steady - state r q jl 35 4 0 c/w
3 ii. die / package information: AO4800 AO4800 l (green compound) process standard sub - micron standard sub - micron low voltage n channel process low voltage n channel process package type 8 leads soic 8 leads soic lead frame copper with solder plate copper with solder plate die attach ag epoxy ag epoxy bond wire au 2mils au 2 mils mold material epoxy resin with silica filler epoxy resin with silica filler filler % ( spherical/flake) 50/50 100/0 flammability rating ul - 94 v - 0 ul - 94 v - 0 backside metallization ti / ni / ag ti / ni / ag moisture level up to level 1 * up to level 1* note * based on info provided by assembler and mold compound supplier iii. result of reliability stress for AO4800 (standard) & AO4800 l (green) test item test condition time point lot attribution total sample size number of failures solder reflow preconditio n normal: 1hr pct+3 cycle ir reflow@240 ?? (260 ?? for green) 0hr normal : 81 lots green: 23 lots 14410 pcs 0 htgb temp = 150 c, vgs=100% of vgsmax 168 / 500 hrs 1000 hrs normal : 3 lots (note a*) 246 pcs 77+5 pcs / lot 0 htrb temp = 150 c, vd s=80% of vdsmax 168 / 500 hrs 1000 hrs normal: 3 lots (note a*) 246 pcs 77+5 pcs / lot 0 hast 130 +/ - 2 c, 85%, 33.3 psi, vgs = 80% of vgs max 100 hrs normal : 52 lots green: 16 lot s (note b**) 3740 pcs 50+5 pcs / lot 0 pressure pot 121 c, 15+/ - 1 psig, rh=100% 96 hrs normal : 70 lots green: 20 lots (note b**) 4950 pcs 50+5 pcs / lot 0 temperature cycle - 65 to 150 deg c, air to air, 0.5hr per cycle 250 / 500 cycles normal : 81 lots green: 2 3 lots (note b**) 5720 pcs 50+5 pcs / lot 0
4 iii. result of reliability stress for AO4800 (standard) & AO4800 l (green) continues dpa internal vision cross - section x - ray na 5 5 5 5 5 5 0 csam na 5 5 0 bond integrity room temp 150 c bake 150 c bake 0hr 250hr 500hr 40 40 40 40 wire s 40 wires 40 wires 0 solderability 230 c 5 sec 15 15 leads 0 die shear 150 c 0hr 10 10 0 note a: the htgb and htrb reliability data presents total of available AO4800 and AO4800 l burn - in data up to the published date. note b: the pressure pot, temperature cycle and hast reliability data for AO4800 l comes from the aos generic green compound package qualification data. iv. reliability evaluation fit rate (per billion): 11 mt t f = 10377 years 500 hrs of htgb, 150 deg c accelerated stress testing is equivalent to 15 years of lifetime at 55 deg c operating conditions (by applying the arrhenius equation with an activation energy of 0.7ev and 60% of upper confidence level on the failure rate calculation). aos reliability group also routinely monitors the product reliability up to 1000 hr at and performs the necessary failure analysis on the units failed for reliability test(s). the presentation of fit rate for the individual product reliability is restricted by the actual burn - in sample size of the se lected product ( AO4800 ). failure rate determination is based on jedec standard jesd 85. fit means one failure per billion hours. failure rate = chi 2 x 10 9 / [ 2 (n) (h) (af) ] = 1.83 x 10 9 / [ 2 ( 2 164) ( 500 ) (258 ) + 2 (164) (1000) (258 ) ] = 11 mt t f = 10 9 / f it = 9 .0 x 10 8 hrs = 10377 years chi2 = chi squared dis tribution, determined by the nu m b e 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 co nditions (ea = 0.7ev and tuse = 55c) acceleration factor [ af ] = exp [ea / k (1/tj u ? 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 = boltznan?s constant, 8.617164 x 10 e - 5 v / k
5 v. quality assurance information acceptable quality level for outgoing inspection: 0.1% for electrical and visual. guaranteed outgoing defect rate: < 25 ppm quality sample plan: conform to mil - std - 105d contacts: wei liu , engineer of failure analysis and reliability wliu@aosmd.com fred chang, manager of failure analysis and reliability fchang@aosmd.com wilson ma, senior director of quality assurance wma@aosmd.com
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