(I) Characterization of materials mechanical properties and environmental effects analysis in the application of Wafer-Level packaging (I) NSC 9--E-7-36 9 8 9 7 3 E-mail: mcyip@pme.nthu.edu.tw accurate reliability design parameters. The long-term reliability and failure mechanism of wafer-level packages constitutive material will be analyzed and discussed. The project is divided into two year to do the research of wafer-level packages constitutive materials visco-elastic/plastic material behavior under different temperature, moisture, strain rate and long-term environment. A experiment is set up to derive the material property and construct the characteristic material curve. Materials fracture modes caused by different (passivation layer) environment attack are analyzed further. polyimide underfill In the aspect of the experiment, the analysis of material constant and mechanical (strain rate) property is achieved by the micro tester - system, and the materials moisture (Young s Modulus) absorption and desorption test is achieved by temperature-moisture chamber high temperature oven and electronic scale. In the aspect of theory, the experimentally obtained data are used to construct the material characteristic curve, in order to derive the effects by the environment attack on the wafer-level sized constitutive material. Abstract Wafer level package is a light weight, small size and low cost package. Wafer level package is a good solution to meet the requirements in the keen competition of electronic packages. Specimen with wafer-level size will be fabricated and measured the mechanical property under the hygro-thermal environment the same as the reliability test, in order to derive the more Keywords: wafer-level packaging; material property; temperature and moisture effect. []
- Qian [8] 6 (epoxy resin) (silica filler) (substrate) (solder) [] 塡 塡 7~ppm/ 塡 (global effect) ~ ppm/ (fast flow underfill) (local effect) (capillarity) Wong[9] (no flow underfill) (micro-pore) 廻 (reflow) (curing) 3 6%RH 廻 [3,] [6] Shi [] SEM 3. (glass transition temperature) / [] Rao [7] Hysol FP 9
(gage length) mm mm.mm( %) ASTMD638-97[] ASTMD88-97[] () (the strip specimen).mm [] ASTMD638-97 ASTMD88-97 3. () - o C (T g ) o C (Sputter) (Spin coating) cm x 3.cm C 7 C mm x mm C C - -3 - - mm/mm/s 3.3 JESD-A3C JESD-A Underfill ASTMD7-98 [3 ] (edge effect) JESD-A () r h h<.r () L W h : (bulk dog bone shape) (thin strip).(wil) h < (end tap) (W + L) mm ( ) mm (3) 6 3 3
(glassy state rubbery state) (7) Temperature o C Strain rate - /s Strain rate JESD-A3C -3 /s Strain rate - /s Strain rate Level 8 8 - /s 3 RH 68( / ) D....6.8... Tensile stress (MPa) 3 Strain rate - /s Strain rate - /s....6.8....6 7. - - Temperature o C Strain rate - /s Strain rate (~7) - -3 /s Strain rate - /s Strain rate - /s 6 8 (8~) (~7) 6 Temperature o C Strain rate - /s Strain rate -3 /s Strain rate - /s 8 Strain rate - /s 6 (8~) (yielding) 6 8 6 8 (strain hardening) T g ( ) 7 3 3 3 Temperature 7 o C Strain rate - /s Strain rate -3 /s
6 Strain rate - /s Temp. = o C Temp. = 7 o C Temp. = o C Temp. = o C - (tangent modulus) ~ 6 [6] 3 () 3 6 7 8 9 3678 (temperature and strain rate 8 - dependence) (3) () Strain rate -3 /s 3 Temp. = o C Temp. = 7 o C () (3) () 3 Temp. = o C Temp. = o C () (6) () i E T, ε (GPa) Tensile Stress (Mpa) 6 8 6 8 i +.6l og 9-3 ε (/ s) +.9 (3) Strain rate - /s Temp. = o C 3 Temp. = 7 o C T g ( 3 Temp. = o C Temp. = o C ) (glassy state) T g ( ) (rubbery state) ( - () Strain rate - /s Temp. = o C Temp. = 7 o C Temp. = o C (glassy state rubbery state) 3 Temp. = o C Tensile stress (MPa) 6 8 6 8 ( ) 8.7 o o T( C) = l og.666t( C) 3.7e T g ) -.88.97.8.3 7.6 3.833 3.68 3.88.9.793.3.7. -.6.7.7. () () (/s) (GPa) - -3 - -
3 E....6.8... (curve fitting) Young's Modulus (MPa).... 3. 3....... -. E- E- E-3. Strain rate (/s) Data Temperature( o C) o C 7 o C o C o C Eqn(6-) fit 6 Young's Modulus (GPa) 6 3 n 6 8 6 Temperature ( o C) n T g Strain rate (/s) Data Ave. - -3 - - 3 (bounding strength) (cross-link) 3 SEM < T g Temperature( o C)) > T g Data Ave. T g T g o C 7 o C () T g SEM o C o C E- E- E-3. Strain rate (/s) 6 Young's Modulus (GPa) Young's Modulus (GPa) 3.3 SEM kv Data Strain rate(/s) () T g SEM - T -3 g - - Egn(6-) fit - 6 8 6 Temperature ( o C) 6
(7 8 9 ) T g - mm/mm/s SEM T g. () ) W 7 - t W Weight gain(%) = % () mm/mm/s W SEM W t W 8 7 - mm/mm/s ) SEM 3 3 C A B A B JEDEC M sat at 68h (M ) 9 - mm/mm/s D SEM (3) 8.376E-6 mm sec 7 Specimen Diameter Thickness Weight (mm) h(mm) W (g) A.8 6.83 B. 6.78 C.76.86 Average.87 6.
(3)[] Mt 8 D(m+ ) π t (3) = exp M π m= (m+ ) h (3) D h M t t M M t M.7 ).6 (Fickian absorption curve). ( )..3. Specimen A W. o =6.83g h =.8mm Specimen B W o =6.78g h = mm Specimen C W. o =.86g h =.76mm (non-fickian 6 8 6 8 absorption curve) Time (hr) 8 8%RH..8.6 (concentration dependent). Fickian behavior curve D=8.376E-6 (mm /s). 6 8 6 8 Time (hr) 3 D M Specimen Slope(/s) sat at D(mm /s) 68hr(g) () A.36 6.38 7.8386E-6 B.67 6.793 8.836E-6 C.63.9 8.3683E-6 () SEM T g 8 Weight gain (%) M t /M. Experimental Data Specimen A Specimen B Specimen C
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