Materials interfaces in flip chip interconnects for optical components; performance and degradation mechanisms

Esser, Robert H.; Strifas, Nickolaos; Christou, A.; Papanicolau, N.

doi:10.1016/s0026-2714(98)00131-0

Cited by 2 publications

(1 citation statement)

References 8 publications

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“…[9][10][11] Among the deposition methods, electrolytic plating is highly recommended for a fine-pitch and lead-free solder because of the stability of the process, the feasibility of fine pitch, and the low cost. [12][13][14][15][16][17][18] Evaporation is too expensive, even though it can deposit very fine-pitch solder bumps. Stencil printing has a much lower cost, but it is highly doubtful for fine-pitch bumping.…”

Section: Introductionmentioning

confidence: 99%

Residual stress and interfacial reaction of the electroplated Ni-Cu alloy under bump metallurgy in the flip-chip solder joint

Kim

et al. 2004

Journal of Elec Materi

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Pure Ni, the Ni-Cu alloy, and pure Cu layers as the under bump metallurgy (UBM) for a flip-chip solder joint were deposited by electrolytic plating. For the pure Ni layer, residual stress can be controlled by adding a wetting agent and decreasing current density, and it is always under tensile stress. The Ni-Cu alloys of different Cu compositions from ϳ20wt.%Cu to 100wt.%Cu were deposited with varying current density in a single bath. The residual stress was a strong function of current density and Cu composition. Decreasing current density and increasing Cu content simultaneously causes the residual stress of the metal layers to sharply decrease. For the pure Cu layer, the stress is compressive. The Cu layer acts as a cushion layer for the UBM. The residual stress of the UBM strongly depends on the fraction of the Cu cushion layer. Interfacial reaction of the UBM with Sn-3.5 wt.% Ag was studied. As the Cu contents of Ni-Cu alloys increased, the dissolution rate increased. Several different intermetallic compounds (IMCs) were found. The lattice constants of alloys and the IMC increase with increasing Cu contents because the larger Cu atoms substitute for the smaller Ni atoms in the crystallites. The Cu content of the IMC are strongly dependent on the composition of the alloys. Ball shear tests were done with different metal-layer schemes. The failure occurs through the IMC and solder.

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Section: Introductionmentioning

confidence: 99%

Residual stress and interfacial reaction of the electroplated Ni-Cu alloy under bump metallurgy in the flip-chip solder joint

Kim

et al. 2004

Journal of Elec Materi

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The reactions between electroless Ni-Cu-P Deposit and 63Sn-37Pb flip chip solder bumps during reflow

Chen

Lin

2000

Journal of Elec Materi

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This study investigates the interfacial reactions between electroless Ni-Cu-P deposit and 63Sn-37Pb solder bumps under various reflow conditions. The morphology of the intermetallic compounds formed at the Ni-Cu-P/Sn-Pb interface changes with respect to reflow cycle, reflow temperature, and reflow time. The (Ni,Cu) 3 Sn 4 compounds with three different morphologies of fine grain, whisker, and polygonal grain form at the Ni-Cu-P/Sn-Pb interface after reflow at 220°C for 15 s. The whisker-shape and polygonal grains detach from the NiCu-P deposit into the Sn-Pb solder during multiple reflows. The (Ni,Cu) 3 Sn 4 compound grows rapidly when the reflow temperature is above the Ni-Sn eutectic temperature, 231°C. A continuous (Ni,Cu) 3 Sn 4 layer forms after reflow at 220°C for 10 min. A 4.5 µm Ni-Cu-P deposit prevents the interdiffusion of Sn and Al atoms across the Ni-Cu-P deposit after 10 reflow cycles at 220°C for 15 s and after reflow at 220°C for 10 min.

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Materials interfaces in flip chip interconnects for optical components; performance and degradation mechanisms

Cited by 2 publications

References 8 publications

Residual stress and interfacial reaction of the electroplated Ni-Cu alloy under bump metallurgy in the flip-chip solder joint

Residual stress and interfacial reaction of the electroplated Ni-Cu alloy under bump metallurgy in the flip-chip solder joint

The reactions between electroless Ni-Cu-P Deposit and 63Sn-37Pb flip chip solder bumps during reflow

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