Connie Korth wrote:

> I'm with JoAnn on this one.  What exactly is 'soda strawing'?
>
> Connie Korth
>
> >IPC is desperately seeking sample boards (for photographic purposes) for a
> >new interactive (CD ROM) training program based on the A-600. The following
> >types of defects samples are needed:
> >
> >o Pink Ring
> >o Solder Mask Soda Strawing
> >o Solder Mask Wrinkles / Ripples
> >o Bare Laminate with Pre-Gellation Particle(s)
> >
> >We could also use samples of "modern looking boards" that have any kinds of
> >defects...
> >
> >Feel free to remove logos, etc. All samples need to be carefully protected
> >to avoid scratches. Please ship them to IPC Video, 7196 Hwy 518 (PO Box
> >389) Ranchos de Taos, NM 87557. Phone (505) 758-7937 ext 202 (Obviously, no
> >logos will be shown - even if you don't remove them. The closeup
> >photography will concentrate on defects only).
> >
> >Sample boards are preferred - rather than photos or slides - to keep all of
> >the imagery consistent.
> >
> >Contributors will receive company credit for "Providing Resources" and our
> >sincere thanks for helping to create an important industry training program.
> >
> >If you need additional info, or have questions, please let me know.
> >
> >Thanks,
> >Mark Pritchard
> >Dir. IPC Video / CBT
> >

Connie & Jo Ann,   If you look at the edge of the PCB and a section of the traces, (IPC's A-600
? Document has a
good picture of this) their is a very small opening next to each side of the trace.


                             /----------\
                           /  |         trace          | \      <--------  Solder Mask
                         /    |                             |   \
PCB top  --------------------------
                           ^                                 ^
                            |                                  |
                            |----------- |-----SODA STRAW down each side of the trace.

IPC has a much better picture of this in their documents but maybe this will do for now. The
problem
with soda strawing, at least one, is that unwanted things like flux can leach up these straws
much like
sap in trees, capillary action. To my knowledge, the time you see this most is with dry film
mask.
Some one can and should correct me on the above statements but this is the basics I can tell you
about.
Hope this helps and I hope the picture comes out OK on your end.


--
         Scott Decker
      AKA: PadMasterson
Praegitzer Design On Location at
 Enterprise Server Group CO3
      Intel Corporation
     Ph: (503)-677-6582

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