In this work the effect of nickel (Ni) plating process on the hydrogen (H) and moisture content of hermetic packages such as those used in optoelectronics was investigated. The work offers an explanation of moisture formation inside hermetic packages by showing that the problem arises from the electroless plating of Ni, which is found to be inherently rich in H. The effects of the Ni plating process, baking, and Au thickness on the moisture and hydrogen content of hermetic packages were thoroughly explored. It was observed that baking the package components before sealing alleviates the problem of moisture formation inside the package but does not fully eliminate it. It was only after changing the Ni plating process from electroless to electrolytic that the moisture problem actually disappeared. This investigation showed that moisture formation inside hermetic packages is due to H evolution from the electroless Ni which eventually reacts with surface oxides to form H2O. SIMS analysis of electroless and electrolytic Ni showed that electroless Ni is around 10-fold richer in H compared with its electrolytic counterpart. SIMS analysis also showed that H content in electroless Ni can be significantly reduced with heat treatment.

In this work we investigated the effect of Nickel (Ni) plating process on the Hydrogen (H) and moisture content of hermetic packages such as those used in optoelectronics. The work offers an explanation of moisture formation inside hermetic packages by showing that the problem arises from the electroless plating of Ni which is found to be inherently rich in H. The effects of the Ni plating process, baking, and Au thickness on the moisture and hydrogen content of hermetic packages were thoroughly explored. It was observed that baking the package components before sealing alleviates the problem of moisture formation inside the package but it doesn't fully eliminate it. It was only after changing the Ni plating process from electroless to electrolytic that the moisture problem actually disappeared. Our investigation showed that moisture formation inside hermetic packages is due to H evolution from the electroless Ni which eventually reacts with surface oxides to form H2O. SIMS analysis of electroless and electrolytic Ni showed that electroless Ni is around ten folds richer in H compared to its electrolytic counterpart. SIMS analysis also showed that H content in electroless Ni can be significantly reduced with heat treatment.

In this work, the root cause of the increase in dark current occurring over time at high temperature in hermetic packages, such as those used in optoelectronic devices, was investigated. It was observed that hermetic Receiver Optical Subassembly (ROSA) devices show continuously increasing dark current when stressed and monitored at 85°C over an extended period of time, reaching, in some cases, values greater than 500nA. However, this increase in leakage current was recoverable once the package seal is broken, and this behavior was found to be very repeatable. Photodetectors from two different suppliers were tested and found to have dark current which is dependent on the fabrication process, as the photodetector (PD) from supplier 1 (PD1) showed three times higher leakage than the photodetector from supplier 2 (PD2). The main difference between the two photodetectors is that the polyimide layer in PD1 in significantly greater than in PD2. It was also observed that 48 hour pre-seal baking at 120°C keeps the dark current constant at much lower levels, but does not stop it completely from rising over time.

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