In BGA chip packages, it is the tiny globe of solder that provides the contact between the chip package and the printed circuit board. Also called a "solder bump." See BGA.
"solder ball." YourDictionary, n.d. Web. 18 August 2018. <http://www.yourdictionary.com/solder-ball>.
solder ball. (n.d.). Retrieved August 18th, 2018, from http://www.yourdictionary.com/solder-ball