High water vapor in semiconductor devices and integrate circuits will influence the product' s electrical characteristics and reliability. As the reliability of requirements increase, water vapor in semiconductor devices and integrate circuits need to be controlled less than 5000ppm. There are three ways which may bring on high water vapor: bad hermeticity of shell,no enough pre-baking or inap-propriate controlling of sealing,and impure nitrogen. Effective methods are put forward to resolve the problems abo...