Electrovert Bravo 8105, Руководство по программированию и эксплуатации

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2-9317-372-00-0 Bravo™ 8105 Programming and Operations Guide 11-113
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Accomplishing the Reflow Process
Section A: Introduction to Process
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Understanding Process
Introduction The most common means to attach a surface mounted component to a circuit is
to apply solder paste, position the device and reflow the solder in a conveyor
oven. The goal of the reflow process is to melt the powder particles in the solder
paste, wet the surfaces being joined together, and solidify the solder to create a
strong metallurgical bond. There are four process zones in conventional reflow
process. These zones are preheat, thermal soak (often shortened to just soak),
reflow and cooling.
Understanding Process If unsatisfactory results are obtained from production, it is necessary to examine
the entire process that produced the finished product.
Troubleshooting the reflow process is a learned skill, resulting from experience
and observation. There is not always a clear–cut connection between defects and
causes.
Because each paste manufacturer produces paste–specific recommendations,
and because printed circuit boards vary widely in complexity and mass, it is not
practical to stipulate exact process stages from design to soldering. There are,
however, some guidelines common to the industry that address general process
and process troubleshooting.
Several variables affect the reflow process, including equipment design, board
layout, solder paste chemistry, throughput requirements, process control, etc. It
is important to understand the relationship of all aspects of the process to
achieve optimum first–pass yields.