AOS Semiconductor Reliability Report AOI2N60 600V, 2A N-Channel MOSFET Rev. A ALPHA & OMEGA Semiconductor, Inc www.aosmd.com AOS Reliability Report 1 The AOI2N60 has been fabricated using an advanced high voltage MOSFET process that is designed to deliver high levels of performance and robustness in popular AC-DC applications. By providing low RDS(on), Ciss and Crss along with guaranteed avalanche capability this part can be adopted quickly into new and existing offline power supply designs. “Commitment to Excellence at Quality & Reliability!” To achieve this vision, AOS continuously strive for the excellence in design, manufacturing, reliability and proactively response to the customer’s feedback. AOS ensures that all the product quality and reliability exceed the customer’s expectation by constantly assessing any potential risk, identifying cause of the suspected failures, driving corrective actions and developing prevention plan within the committed 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 product 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 continuously improving the product quality. Table 1 lists the generic reliability qualification requirements and conditions: Table 1: AOS Generic Reliability Qualification Requirements Test Item Test Condition HTGB Temp = 150c , Vgs=100% of Vgsmax HTRB Solder reflow precondition HAST Temp = 150C , Vds=80% of Vdsmax 168hr 85c /85%RH + 3 cycle reflow @260c (MSL level 1) 130 +/- 2C , 85%RH, 33.3 psi, Vgs = 100% of Vgsmax Sample size Acc/Reject 77 pcs / lot 0/1 77 pcs / lot 0/1 - The sum of PCT ,TC, HAST and Power Cycle 0/1 96hrs 55 pcs / lot 0/1 Time Point 168 / 500 hrs 1000 hrs 168 / 500 hrs 1000 hrs Pressure Pot 121C , 29.7psi, 100%RH 96 hrs 77 pcs / lot 0/1 Temperature Cycle -65C to 150C, air to air, 250 / 500 cycles 77 pcs / lot 0/1 Power Cycle Tj = 125 C 4286 cycles 77 pcs / lot 0/1 AOS Reliability Report 2 High Temperature Gate Bias (HTGB) & High Temperature 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 lifetime in field operation & long term device level reliability can be determined. FIT rate is calculated by applying the Arrhenius equation with the activation energy of 0.7Ev and 60% of upper confidence level at 55 deg C operating conditions. Solder reflow precondition (pre-con) Solder reflow precondition is the test that simulates 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 moisture then bake in pressure pot, or being placed into 85% RH, 85 deg C environment for 168 hrs. Then they will be run through a solder reflow oven with temperature at 260ºC+/- 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 mechanical 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 cycles. Pressure Pot (PCT) PCT test is the test that measures the ability of the device withstand to moisture and contaminant environment. The test is done under enclosed chamber 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 devices under high humidity, high pressure environment under DC bias condition. If ionic contamination involved, 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 extremes 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 results based on the device/process families and the package types, respectively. AOS Reliability Report 3 Table 2 Reliability Test and Package test Result: Test Item Test Condition Time Point HTGB Temp = 150c , Vgs=100% of Vgsmax 168hrs 500 hrs 1000 hrs HTRB Temp = 150C , Vds=80% of Vdsmax 168hrs 500 hrs 1000 hrs Solder reflow precondition 168hr 85c /85%RH + 3 cycle reflow @260c Total Sample size Number of failure 77 308 (Note A) 0 77 308 (Note A) 0 - 3058 (Note A) 0 (MSL level 1) HAST 130 +/- 2C , 85%RH, 33.3 psi, Vgs = 80% of Vgs max 100 hrs 440 (Note A) 0 Pressure Pot 121C , 29.7psi, 100%RH 96 hrs 1078 (Note A) 0 Temperature Cycle -65C to 150C, air to air, 250 / 500 cycles 1232 (Note A) 0 Power Cycle Tj=125C 7500 cycles 308 (Note A) 0 Note A: The reliability data presents total of available generic data up to the published date. AOS Reliability Report 4 Reliability Evaluation: FIT rate (per billion): 6 MTTF = 20661 years The presentation of FIT rate for the individual product reliability (AOI2N60) is restricted by the actual burn-in sample size of the selected product. Failure Rate Determination is based on JEDEC Standard JESD 85. FIT means one failure per billion hours. 2 9 Failure Rate (FIT) = Chi x 10 / [2 (N) (H) (Af)] 9 = 1.83 x 10 / [2 (2x77x168+2x4x77x1000) (258)] =6 9 8 MTTF = 10 / FIT = 1.81 x 10 hrs = 20661 years Chi²= Chi Squared Distribution, determined by the number 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 = 55C) Acceleration Factor [Af] = Exp [Ea / k (1/Tj u – 1/Tj s] Acceleration Factor ratio list: Af 55 deg C 70 deg C 85 deg C 100 deg C 115 deg C 130 deg C 150 deg C 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 = Boltzmann’s constant, 8.617164 X 10 -5eV / K AOS Reliability Report 5