Variability reduction in stencil printing of solder paste for surface mount technology
Competition in stencil printing to produce excellence in the finished product is intense. Faults in the printing process are a major source of board failure. Studies have shown that over 63% of defects identified after reDow originated from the solder paste printing ( A. Lotfi ,1998 ) . Howeve...
Saved in:
Main Author: | |
---|---|
Format: | Thesis |
Language: | English |
Published: |
1998
|
Subjects: | |
Online Access: | http://eprints.uthm.edu.my/7697/1/24p%20MUSTAFFA%20IBRAHIM.pdf |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | Competition in stencil printing to produce excellence in the finished product
is intense. Faults in the printing process are a major source of board failure. Studies
have shown that over 63% of defects identified after reDow originated from the
solder paste printing ( A. Lotfi ,1998 ) . However. understanding these failures are a
challenging problem as the printing process has a large number of non linearly
dependent variables such as factors relating to paste (formulation. viscosity), the
environment (temperature, humidity) and machine parameter (alignment, pressure
and speed of squeegee, blade hardness etc). The process engineer is challenged to
widen the process window so that future modifications to the process, such as the
addition of a new component, can be achieved with little. if any, change in materials
or process parameters. This thesis reports the effect of temperature and humidity
variation from the manufacturing environment on the solder paste consistency and
optimization of the essential parameters of squeegee pressure, squeegee speed.
separation speed and print gap. The outcome of variation in temperature and
humidity to the solder paste viscosity were analyzed and tests were done to
determine the characteristic of the solder paste. The tests results indicate that the
temperature and humidity has an impact on the solder paste printability. thus some
attempts must be taken to control these variables. For parameter optimization. the
analysis was carried out using statistical optimization. The main aim was to combine
these parameters with three main pitch categories to produce the acceptable print
formation. The results showed that. the ideal print result requires optimum statistical
combinations of four parameters essentially related to a particular pitch. It is also
shown that there is a diversity and contrasts of the combination of the parameters for
each category of pitch. Detailed explanations as to the phenomenon are outlined in
the thesis. |
---|