Hermetic sealing process with atmospheric pressure vibration for LSI packages

The authors present a hermetic soldering technique, the atmospheric pressure vibration (APV) process, which periodically changes the ambient pressure while the solder is fused at the sealing area of the LSI package. The kinetic energy induced by the ambient pressure change improves the wettability of the fused solder, which results in realizing a good hermeticity of the sealing area without mechanically handling the package. The sealing apparatus is made to control the two key parameters of the kinetic energy, the amplitude and the rise time of the ambient pressure change. The mechanism of this process to improve the hermeticity is investigated with a soft X-ray micrograph analysis for the sealed packages