文档介绍：Process Parameters Optimization
For Mass Reflow Of ponents
Abstract
The research summarized in this paper will help to address some
of the issues associated with solder paste mass reflow assembly
of ponents. Attachment pad design, stencil design,
component ponent spacing, component orientation, flux
type, and solder paste reflow atmosphere were the major variables
researched during the project. The two major responses from the
experimentation were assembly yield and assembly quality.
Assembly yield defects, such as tombstones (open solder joints),
solder bridges, and solder balls (beads) were used to determine
the assembly yield. Solder joint shape, solder appearance, and
solder volume (eptable low, acceptable or eptable
high) responses were used to determine the quality of the assem-
bly process. bination of flux type and reflow environment
were found to have the largest impact in the number of assembly
defects produced. Boards assembled with no-clean solder paste
and reflowed in an air atmosphere exhibited the best yields with
the highest tolerance for attachment pad dimension variation.
Conversely, assembly processes using no-clean solder paste with
a Nitrogen reflow atmosphere generated the largest number of
assembly defects and was found to be the most sensitive to
changes in the attachment pad design.
attachment pad design. Five different stencil
aperture designs were tested for each attachment
pad design. No-clean and water-soluble flux
chemistries were tested in both air and Nitrogen
reflow environments. Component ponent
spacing was tested at four different levels at
both zero and y ponent orienta-
tions. Stencil thickness, stencil fabrication, attach-
ment pad metallurgy, solder mask type, screen
printer process settings, component placement
system, thermal profile, and reflow system were
major parameters that were fixed during the
research project.
Market Drivers and Attributes
f