Journal of SMT Article
0.4 mm SOLDER BALL PITCH CHIP SCALE PACKAGING AND DROP TEST PERFORMANCE
Company: STATS ChipPAC Inc.
Date Published: 10/1/2007 Volume: 20-4
To do solder joint evaluation, different lead-free compositions ( SAC1205Ni (Sn1.2%Ag0.5%Cu + Ni addition), SAC105 (Sn1.0%Ag0.5%Cu), SAC2505 (Sn2.5%Ag0.5%Cu) ) of solder ball on Ni/Au, OSP (Organic Solderability Preservative) and DIG (Direct Immersion Gold) finished ball pad were investigated with zone shear test and drop test with JEDEC specified condition (JESD22-B111) together with BST(Ball Shear Test) and IMC(Intermetallic Compound) cross-section analysis up to 1000hrs at 150° C. BST values of the prepared samples showed substrate surface finish dependency on its average value. Failures with OSP finish legs without pre-cleaning in the zone shear test tells that 0.4mm pitch is less favorable for removing oxide layers than larger solder ball pitch due to its small solder resist opening size. Among the combination of experimental legs, Ni/Au with SAC 105, OSP with SAC1205Ni and DIG with SAC1205Ni show similar drop performance and meet JEDEC criteria of no failure of minimum of 30 drops in the test.
Keywords: 0.4mm pitch, FBGA, Drop performance
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