CHAPTER 3 SOLDERING CONDITIONS

Figure 3-2-4 shows the moisture absorption characteristics of QFPs of various epoxy resin thickness when the packages are stored at an ambient temperature (Ta) of 5 to 25°C and a relative humidity (RH) 20 to 65%.

The vertical axis of this figure indicates the moisture absorbed by the packages divided by the resin weight at the beginning of storage and expressed in percentage. The horizontal axis indicates the lapse of time. As shown in this figure, the moisture absorption rate varies depending on the thickness of the resin i.e., the thinner the package, the quicker the package absorbs moisture.

It is recommended that NEC Electronic's packages be stored at 5 to 25°C, 20 to 65%RH after the dry pack was opened.