Green Product Infineon 2nd level reliability of tin plated components Dr. Marc Dittes CAT AIT PGP Board level reliability, Sn finish on components Outline • Experimental parameters • Testboard, paste, components, T-cycling, Shear test • Reflow profile SnPbAg • Reflow profile SnAgCu • Reliability of components with matt pure tin finish • TQFP-100-5 (Cu) • TQFP-100-1 (FeNi42) • VQFN-48-4 • Summary Dr. Marc Dittes CAT AIT PGP Board level reliability, Sn finish on components Experimental parameters Testboard: Stencil thickness: Stencil opening Solder paste: 1,0 mm FR 4, 4 layers, symmetric layout (bottom = top) Finish Cu/OSP and Ni/Au 125 µm = pad size SnPb36Ag2 (Kester 229d, class 3 ROL1) SnAg3.8Cu0.7 (Multicore CR32, class 3, ROL0) Components: P-TQFP-100-1 (FeNi42-Leadframe) P-TQFP-100-5 (Cu-Leadframe) P-VQFN-48 (Cu-Leadframe) P-DSO-12 (Cu Leadframe) 24 components per type and test, daisy chain chip T-cycling: -40 °C / + 125 °C, T-shock air to air, dwell time 15 min Dr. Marc Dittes CAT AIT PGP Electrical failure detection online (daisy chain) Shear test: speed 500 µm / s Board level reliability, Sn finish on components Experimental parameters Reflow profile for SnPbAg assembly Dr. Marc Dittes CAT AIT PGP Board level reliability, Sn finish on components Experimental parameters Reflow profile for SnAgCu assembly Dr. Marc Dittes CAT AIT PGP Board level reliability, Sn finish on components DSO-12 DSO-12 3000 shear force in g 2500 0 cycles 1000 cycles 2000 cycles 3000 cycles 4000 cycles 2000 1500 1000 500 As soldered (SnPbAg on Cu/OSP) 0 OSP/SnPbAg NiAu/SnPbAg OSP/SnAgCu NiAu/SnAgCu • No electrical or mechanical failure up to 4000 T-cycles • Excellent reliability with SnPb and lead-free solder for both board finish types Dr. Marc Dittes CAT AIT PGP • Solder coarsening without cracks for SnPbAg • First cracks for SnAgCu along intermetallic phase after 4000 cycles After 4000 T-cycles (SnPbAg on Cu/OSP) Board level reliability, Sn finish on components TQFP-100-5 (Cu) 1400 Shearforce in g 1200 0 cycles 1000 cycles 2000 cycles 3000 cycles 4000 cycles TQFP-100-5 1000 800 600 400 200 As soldered (SnAgCu on Ni/Au) 0 OSP/SnPbAg NiAu/SnPbAg OSP/SnAgCu NiAu/SnAgCu • No electrical or mechanical failure up to 4000 T-cycles • Excellent reliability with SnPb and lead-free solder for both board finish types Dr. Marc Dittes CAT AIT PGP • Solder coarsening without cracks for SnPbAg • First intergranular cracks for SnAgCu starting at solder heel after 4000 cycles After 4000 T-cycles (SnAgCu on Ni/Au) Board level reliability, Sn finish on components TQFP-100-1 (FeNi42) As soldered (SnPbAg on Cu/OSP) As soldered (SnAgCu on Cu/OSP) As soldered (SnPbAg on Cu/OSP) Dr. Marc Dittes CAT AIT PGP After 2000 T-cycles (SnPbAg on After 2000 T-cycles (SnAgCu on Cu/OSP) Cu/OSP) After 2000 T-cycles (SnPbAg on Cu/OSP) Board level reliability, Sn finish on components TQFP-100-1 (FeNi42), ctd Shearforce in g 1200 1000 800 600 99.9 SnPbAg on Ni/Au % 70 50 30 20 10 4 2 400 1 200 0.4 2479,889 1400 0 cycles 1000 cycles 2000 cycles 3000 cycles 4000 cycles C um u lative F ailure s TQFP-100-1 0.2 0 OSP/SnPbAg NiAu/SnPbAg OSP/SnAgCu NiAu/SnAgCu 1000 2000 3000 4000 5000 4000 5000 Number of Thermal Cycles 99.9 Dr. Marc Dittes CAT AIT PGP • Crack propagation along intermetallics for SnPbAg solder and intergranular for SnAgCu solder • Limited reliability due to cte mismatch of solder and FeNi42 leadframe 70 50 30 20 10 4 2 1 0.4 2984,65 • SnAgCu on Ni/Au shows slightly superior reliability SnAgCu on Ni/Au % C um u lativ e F ailures • 100 % mechanical failure for SnPbAg and SnAgCu after > 2000 cycles 0.2 1000 2000 3000 Number of Thermal Cycles Board level reliability, Sn finish on components VQFN-48-4 As soldered (SnPbAg on Cu/OSP) As soldered (SnAgCu on Cu/OSP) As soldered (SnPbAg on Cu/OSP) Dr. Marc Dittes CAT AIT PGP After 4000 T-cycles (SnPbAg on After 4000 T-cycles (SnAgCu on Cu/OSP) Cu/OSP) After 4000 T-cycles (SnPbAg on Cu/OSP) Board level reliability, Sn finish on components VQFN-48-4, ctd 99.9 99.9 SnPbAg on Cu/OSP SnAgCu on Cu/OSP % 70 50 C um u lative F ailure s 30 20 10 4 2 30 20 10 4 2 1 1 5233,471 0.4 0.2 1000 2000 3000 4000 5000 0.4 3703,771 C um ula tiv e F a ilu res % 70 50 0.2 6000 1000 Number of Thermal Cycles • Non-wetting of cut edge without significant influence on reliability Cumulative Failures • Crack propagation intergranular 5000 70 50 30 20 10 4 2 1 0.4 3891,117 Dr. Marc Dittes CAT AIT PGP 4000 SnAgCu on Ni/Au % • First electrical failures >> 2000 cycles 3000 99.9 • Shear strength not tested (non-leaded) • Characteristic lifetime larger with SnPbAg (>4000 T-cycles ) solder than with SnAgCu solder (>3700 T-cycles) 2000 Number of Thermal Cycles 0.2 1000 2000 3000 Number of Thermal Cycles 4000 5000 Board level reliability, Sn finish on components Summary • The reliability is mainly influenced by the solder alloy (and the leadframe material) • SnAgCu joints with slightly lower reliability for Cu-leadframe based components and slightly superiour reliability for FeNi42 based components compared to SnPbAg joints • Little but inconsistent influence of the board pad metallisation can be observed • > 4000 T-cycles passed with 14 x 14 gullwing package (Cu leadframe) and 6 x 7 power package • > 2000 T cycles passed with 7 x 7 non-leaded QFN package • > 1500 cycles passed with 14 x 14 gullwing package (FeNi42 leadframe) Dr. Marc Dittes CAT AIT PGP Conclusion The board level reliability of tin plated components is comparable to that of SnPb plated components.