Rapidly Solidified Soft Solder Die-Attach Technology

Pinamaneni, S.; Solomon, Daniel Maurice

doi:10.1109/tchmt.1986.1136671

Cited by 5 publications

(1 citation statement)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This makes the two-step bonding processes more convenient: the chip attachment using AuSn eutectic and lid sealing using Sn-rich solder. Accordingly, compared to AuSn eutectic, the use of Sn-rich solder for lid sealing has three potential advantages: plastic strain, lower bonding temperature, and lower cost [13], [14]. Gold is very expensive and its price will only go up with time.…”

Section: Introductionmentioning

confidence: 99%

Fluxless Hermetic Lid Sealing Using Electroplated Sn-Rich Solder

Kim

Wang

Lee

2008

IEEE Trans. Comp. Packag. Technol.

View full text Add to dashboard Cite

A new fluxless hermetic sealing technique using electroplated Sn-rich soft solder is reported. Specific glass (SCG72) is chosen as lid material to seal alumina packages. It has nominal coefficient of thermal expansion of 7 ppm/ C, close to that of alumina. Alternatively, sapphire can also be used as the lid material. A thick Sn layer is plated over the Cr/Au patterned glass wafer, followed immediately by thin Au layer. This outer Au layer prevents the inner Sn from oxidation. In bonding, the glass lid is placed over the package rim which has a metallization structure of W/Ni/Au. The fluxless sealing process is performed in vacuum (50 millitorrs) to suppress tin oxidation. Compared to bonding in air, the oxygen content is reduced by a factor of 15 200. Fluxless bonding is valuable in many hermetic sealing applications such as microelectromechanical systems (MEMS), sensors, photonic devices, and imaging devices. Nearly void-free sealed joints are achieved with Sn-rich composition. Helium leakage tests are performed to evaluate hermetic quality. Scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) is used to evaluate the composition and microstructure of the sealing joints. The results show how the Sn-rich solder reacts with the W/Ni/Au on the package. This new sealing process can be applied to nearly all devices and packages that require hermetic sealing.

show abstract

Section: Introductionmentioning

confidence: 99%