Before revision: For example, in the case of a ball grid array package, the pre-desposited solder ball on the package and the solder paste applied to the circuit board may both melt, but the melted solder does not join.
After revision: For example, in the case of a ball grid array package, the pre-deposited solder ball on the package and the solder paste applied to the circuit board may both melt, but the melted solder does not join.