文档介绍：Reworking BGAs/CSPs Using Lead-Free Solders
Time. Cost. Quality. Repeatability. These are the primary concerns of the repair and
rework cycle. Too much time means excess cost which is not acceptable. Poor quality has
never been an option with electronics manufacturing. Repeatability requires process
control, of course, but being able to quickly duplicate precise heating profiles – from
operator to operator, facility to facility – underlies the entire repair and rework process,
feeding back to time, cost and quality.
Oh for the days of through-ponents and tin-lead solder. Just heat the iron and go.
Component profiles were plex, operators could see all connections and the
properties of solder were well understood. You didn’t have to be a rocket scientist to
work the repair and rework bench.
Those days, however, are long gone. Today it’s small, sensitive array packages with
complex profiles and hundreds of connections that can only be seen with sophisticated
vision systems. Operator turnover is great; yet, operator experience with array packages
is essential if time and quality goals are to be achieved.
Let’s now add another variable: lead-free solders. Reflow temperatures are higher, time
above the higher reflow temperatures are different, appearance of the joint is
considerably different, and the need for process control is even grea