Dip solder paste—not just for PoP and array packages but leaded too!
soldering.
Dip solder paste is available from many
of the well know solder suppliers and has
the following basic specification. It may be
Y.Cheetah
more difficult to find a tin/lead product
as the majority of products available are
lead-free. Through experiments with a
suitable dispensing grade, tin/lead may be
available.
Basic procedure for rework of a conven-
tional surface mounts fine pitch packages:
1. Inspect the board area and pads prior
Experience innovative
to component placement
2. Place paste on a dip plate of flat glass
technology in Y.Cheetah
slide and metre the depth of the paste
3. Lower the component into paste and
then lift clear from the surface
4. Inspect lead coverage prior to
placement
Zoom
+
deploying twin magnification axis
5. Run the correctly defined component
■ Highest grayscale resolution and image
rework profile cycle
quality for the entire inspection
6. Inspect the joints after cooling ■
No time-consuming adjustments
of tube settings
As dip paste has a lower metal content and
■
some products are designed for nitrogen
No detector adjustments or calibration
reflow only, it’s important to discuss with
the supplier issues of slumping and solder
balling. Also, during rework with hot air
the volume of air or nitrogen may have to
be reduced and the preheat time increased
PowerDrive for twin magnification axis
■ Unmatched effective power increase
to avoid slump, which is less of a problem
for brilliant images
with IR rework. It is important to profile
a board assembly for rework for any large
■ Faster image acquisition with ultimate
packages, which should be done as part of
speed for Y.QuickScan® in µCT applications
the NPI activity rather than left to chance
■ Flexibility to address most challenging
when the first product requires rework in
inspections
volume production. Many companies leave
rework of large devices to chance and often
■ Inspection at reduced distance and
never give rework departments the tools to
lower tube power
do the job effectively.
■ Easy operation saves inspection time
Mini stencils still have their place
during rework and are an ideal solution
for quad flat no lead (QFN) and land grid
array (LGA) packages. As the terminations
are just a few thousands of an inch from Y.Cheetah X-ray inspection System
the body of the package, dipping paste is
■ Secure your findings with brilliant
not a solution for QFN/LGA. Even with
X-ray images
the extremely accurate height control
■ Any task in your daily routine solved
of rework placement systems, smearing
quickly
of the paste is a problem, with the large
surface. The paste can also capillary to

the component body surface. Printing the in
Munich
component is a better solution and covered
in a previous Global SMT column.
Visit
us
at
productronica
11
th
–
13
th
2009
Bob Willis is a process engineer working in
November
the electronics industry, providing training,
consultancy and process/product failure
Hall:
A2,
Booth:
330
analysis. Bob offers on site workshops on
For further information please contact our sales
conventional and lead-free manufacture. Bob
organization or visit us at www.yxlon.com
will be running three new US workshops at
APEX 2010. Bob is happy to assist you set up

and optimise production lines for users and also
YXLON. The reason why
provides conferences and workshops worldwide YXLON International GmbH, a company of the COMET Group. Essener Bogen 15, D-22419 Hamburg,
www.bobwillis.co.uk
T: +49 40 527 29 - 0, F: +49 40 527 29-170, E-mail: yxlon@hbg.yxlon.com, www.yxlon.com
www.globalsmt.net Global SMT & Packaging – October 2009 – 5
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