ADDA Fan Life Test 1 SCOPE 1 MTTF

ADDA Fan Life Test 1

SCOPE 1. MTTF Definition 2. MTTF Condition & Procedure 3. Temperature Acceleration Factor 4. MTTF Calculation & Expect 5. Test Result 2

1. MTTF Definition MTTF: Mean Time To Failures It should be used in a non-repairable system setting. In ADDA life report, ADDA will not repair the failed fans during life experiment. 3

2. MTTF Condition & Procedure Condition AB 0705 HX-LB(X 1 A) life expectancy = 20000 Hrs at 60℃, and ADDA expect: 1. Sample number: 200 pcs 2. 70℃ Burn-in test time: 2160 hrs 3. Failure number: 1 pcs Formula Calculation: (T / r) × e (ΔH / K) x ( 1 — 273+Tl 1 ) 273+Th 4 = 20543 hrs

2. MTTF Condition & Procedure 5

2. MTTF Condition & Procedure 1. Sampling Plan 1. 1 Use set-up test time and sample to do the MTTF test before mass production. 1. 2 From start to the end of test about 2000 hrs and sample used 100 ~ 200 pcs. 2. Operation Step 2. 1 Assign numbers to sample with 01~100 or 01~200. 2. 2 Measure their character first. Shall be current and RPM for 3 min. 2. 3 Put the samples into the oven. Operated fan to rated voltage. 2. 4 Set the temperature 70℃ then operating the oven. 6

2. MTTF Condition & Procedure 2. 5 Checking the test fan if they were acting normally to time Am 08: 00 everyday, and recorded. 2. 6 When the test time till 2000 hrs and complete the test, turn off fan and oven power, carried out all the samples, make final character test, current and RPM for 3 min. Note: The test time completes in the working time (08: 00~17: 00) and more than 2000 hrs at least. • Failure Definition 1. The fan doesn’t work. 2. RPM overtakes 30%. 3. The current overtakes 30% 7

3. Temperature Acceleration Factor ΔH = Acceleration coeffient K = Botltzmann’s coeffient = 8. 623 x 10 -5 Tl = 30、40、50、60 and Th=70 input (1) A. F TEMP = e (ΔH / K) x ( 1 — 273+Tl 1 ) 273+Th …. . (1) go in the 30、 40、50、60 to 70℃ accelerate level number. 8

4. MTTF Calculation & Expect • 70℃, 90 % Confidence Level MTTF calculation T (Total test time) = (Sample - r)×Test time(Hrs) + r 1+ r 2+ r 3 +…… Note: Present the fan failure numbers, r 1、r 2、r 3、…. . present the fan first failure time, second failure time, third failure time, …… 9

The probability of fan failure 10% (L 10) Reliability function R(t) = e (-λt ) Unreliability function F(t) = 1 - R(t) e = expontial index, t = time, λ= 1 / MTTF, Take t = L 10, so F(L 10) = 1 - R (L 10) 10% = 1 - e (-λL 10) 90% = e (-λL 10) ln(90%) = ln [ e (-λL 10)] -0. 105361 = -λL 10 get L 10 = MTTF * 0. 105361 L 10≒ MTTF / 9. 5 10

5. Test Result 11

5. Test Result 12