Drying of moisture-absorbing SMD, all humidity-sensitive SMDs are found to have humidity indicator 30% or more when the seal is opened, or the SMD is not finished in the specified time after unsealing, and the SMD of the over-time storage, etc. It must be removed wet and dried before mounting.
The drying method is divided into low temperature drying method and high temperature drying method.
1) Low temperature drying method. Oven temperature: (40+2) °C; relative humidity: <5%; drying time: 192h.
2) High temperature drying method. Oven temperature: (125 ± 5) °C; drying time: 5-48h.
Precautions for using of humidity sensitive devices:
A sealed package containing desiccant does not require high vacuum because the high vacuum facilitates the diffusion of moisture within the bag. The sealed date of the sealed package and the minimum 12-month storage life are not the expiration date of the components used in the package. After the bag is opened, the reading of the humidity indicator card should be strictly used as a judgment factor as to whether drying is required.
Components that have never been exposed and stored in a drying cabinet with an RH of 10% have a storage life. Even if it is not exposed to room temperature, it will exceed its hygroscopic critical level.
When the conditions in the workshop exceed 30 °C/60% RH, the service life indicated on the MSD label is invalid, and the actual on-site using life must be degraded. The board must be baked before rework to avoid damage to the moisture sensitive device during local reflow.