Orient Semiconductor Electronics Philippines, Inc. 6 Ring Road, Light Industry & Science Park II, Brgy. Lamesa, Calamba, Laguna OSEP NEMI Whisker Test Study for SOIC 8L Package (Sept. 16, 2003 NEMI Revision 4.5) QRA Department - CQE Section Reliability Group Orient Semiconductor Electronics Philippines, Inc. 6 Ring Road, Light Industry & Science Park II, Brgy. Lamesa, Calamba, Laguna OSEP NEMI Whisker Test for SOIC Package 1 Scope This evaluation addresses NEMI’s three different test condition requirement for evaluating whisker growth i.e. two isothermal storage conditions and one temperature cycling condition. 2 Purpose To evaluate and monitor the propensity of Matte Tin plating to grow whisker for various conditions after assembly. The long term reliability of electronic assemblies can be compromised by electrical shorting that may be induced by metal whisker formations that have been known to occur in, but are not limited to, platings with high tin content. QRA Department - CQE Section Reliability Group Orient Semiconductor Electronics Philippines, Inc. 6 Ring Road, Light Industry & Science Park II, Brgy. Lamesa, Calamba, Laguna 3 Test Equipment 3.1 Scanning Electronic Microscope SEM is used to make observations with a magnification capability of 100, 3kX then take photos of the test specimen. SEM Supplier : HITACH Model : S-3500N 3.2 Temperature Cycling Equipment An air-to-air two chamber temperature oven which is capable of cycling from -80 to +200°C temperature. Supplier : Votsch Model : VT 7012 S2 3.3 Temperature Humidity Storage A temperature/humidity storage chamber which is capable of 30 to 100°C, 40 ~100% Relative Humidity environments. Supplier : Votsch Model : VC 2033 QRA Department - CQE Section Reliability Group Orient Semiconductor Electronics Philippines, Inc. 6 Ring Road, Light Industry & Science Park II, Brgy. Lamesa, Calamba, Laguna 4 Test Conditions The condition below defines three separate environmental stresses in which parts must be tested to generate whiskers on the test components. 4.1 Ambient conditions Test condition: 25±5°C; 30~80% RH Duration: 5000 hours 4.2 Temperature and Humidity Soak Test condition: 85°C; 85 % RH Duration: 6 months 4.3 Temperature Cycling Test Test condition: -55+0/-10°C to 85+10/-0 °C; 10 min. dwell time Duration: 1000 cycles QRA Department - CQE Section Reliability Group Orient Semiconductor Electronics Philippines, Inc. 6 Ring Road, Light Industry & Science Park II, Brgy. Lamesa, Calamba, Laguna 5 Evaluation Results 5.1 After 5000H Ambient condition Exposure Suspected mounds were found on all samples. Refer to below SEM photo. Approx. Measurement is 3.02 µm QRA Department - CQE Section Approx. Measurement is 6.42 µm Approx. Measurement is 10.26 µm Reliability Group Orient Semiconductor Electronics Philippines, Inc. 6 Ring Road, Light Industry & Science Park II, Brgy. Lamesa, Calamba, Laguna 5.2 After 5000H Temperature and Humidity Soak Whisker formation were found after 5000H Temperature and humidity soak with a maximum measurement of approximately 15.19µm which is still acceptable base on NEMI 40µm requirement. Refer to below SEM photo. QRA Department - CQE Section Reliability Group Orient Semiconductor Electronics Philippines, Inc. 6 Ring Road, Light Industry & Science Park II, Brgy. Lamesa, Calamba, Laguna 5.3 After 1000 cycles Temp. Cycle Test Whisker formation were found after 1000 cycles TCT with a maximum measurement of approximately 23.5µm which is still acceptable base on NEMI 40µm requirement. Refer to below SEM photo. QRA Department - CQE Section Reliability Group