Alpha Emission Measurements of Lids and Solder Preforms on Semiconductor Packages

Measurements of the alpha emission activity of metal lids manufactured for the hermetic sealing of semiconductor packages indicate that the activity level is less than 0.05 counts/h/cm². Probably, the alpha emission activity is in the area of 0.01 counts/h/cm². This low level of alpha emission is made possible by the use of a chelating compound in the electroplating hath used for plating the lids. Base metal from which the lids are manufactured is monitored for alpha emission before plating. Only that base metal is used which has extremely low level activity. A graphical representation of the counting statistics for measuring alpha emission is developed in such a way as to be most convenient for use in the Quality Control Department of the manufacturer and user of the lids.