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1996
Conference Paper
Titel
Self-aligned, fluxless flip-chip bonding technology for photonic devices
Abstract
The self-aligned flip-chip (FC) bonding technique is a very attractive means for the assembly of photonic devices containing multiple optical as well as electrical waveguide interconnects. In this article we propose a fluxless FC-bonding technology which nevertheless ensures efficient solder oxide reduction by applying molecular hydrogen (H2) under vacuum conditions. Bonding experiments were carried out in a newly developed FC-bonder of which some interesting details are reported. Reproducable bonding accuracies below the required tolerances for fiber to tapered waveguide coupling of <or=3 mu m have been achieved. Using eutectic tin-lead (SnPb 60/40) solder and platinum (Pt) as a wettable pad metallization these bonding results have been obtained at moderate temperatures (250 degrees C) and heating durations (2 min). An investigation on the oxidation kinetics of molten SnPb 60/40 solder confirms the ability of H2 to reduce solder oxides when thermodynamic boundary conditions are met. The leach resistance of the Pt thin-film metallization (300 nm) has been prooved by SIMS depth profiles for the required bonding temperatures and durations.
Tags
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flip-chip devices
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metallisation
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optical fabrication
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optical waveguides
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oxidation
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soldering
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self-aligned fluxless flip-chip bonding technology
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photonic device
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optical waveguide interconnect
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electrical waveguide interconnect
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assembly
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fiber to tapered waveguide coupling
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eutectic tin-lead solder
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oxidation kinetics
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thermodynamic boundary conditions
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leach resistance
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platinum thin-film metallization
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sims depth profile
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250 c
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snpb
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pt
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h2