Plastic packages have been used for years, but it is only very recently that I've heard of moisture absorption becoming big issue. Clearly, with such dramatic effects on reliability, it can't be that we just were ignorant of a long-standing problem. What is it about these parts that causes the moisture sensitivity, or why has it become such an issue recently?
--Bill
The plastic packages used in through hole technology were never subjected to the extreme temperatures of surface mounting. When a small amount of moisture is absorbed and then heated during surface mounting, the package can fracture or even explode when the moisture turns to steam.
-- Greg snipped-for-privacy@hotmail.com.invalid (Remove the '.invalid' twice to send Email)
ignorant
Actually its been an issue ever since plastic has been used atleast as far back as I know 25yrs+. ofcourse the plastics are not your typical "plastic" but are engineered to have the kinds of properties needed to house ICs. They need to resist moisture, need to be strong enough, and mustn't contain too much radioactive material, that was the big one that cought DRAM folks off gaurd 20yrs ago when the US found out how much better Japan was at packaging.
Theres far more to it than that, google chip packaging etc to find more
regards
johnjakson_usa_com
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.