Hi,
Just one question... are OSP users concerned with dendrite growth?
Isn't ENIG safer in regard of dendrite growth?
Very Best Regards
Roland
PCB Consultant - Company viability, Technical viability, Technology choice,
Yield improvement, Company Strategy, Equipment choice, Company acquisition
Roland Jaquet - Tel. +41-22-880-0405 - Fax. +41-22-880-0409 - Cell
+41-79-203-3723
_______________________________________________________________________
----- Original Message -----
From: Mike Lang <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 08, 2000 4:26 PM
Subject: [TN] OSP and Fine Pitch
Hi gang,
A few general questions regarding fine pitch SMT assembly:
1) My research indicates the "industry starting point" for fine pitch
(0.020" pitch) solder pad and stencil design is 0.012" wide PCB solder pads
and 0.010" wide laser cut stencil apertures in 0.005" or 0.006" thick
stencils. I find that using these parameters I still tend to get some
solder shorts. Any comments about better pad / aperture designs?
2) I am using HASL, but recognize the benefits of going to OSP (flatter
among other things). My concern is the bare copper left on the PCB since
the paste does not fully wet out the pad. Does anyone have comments, or
better yet, test data which demonstrates what is acceptable?
3) Another HASL / OSP concern... PCB is double sided reflow using no clean,
and then has a small quantity of hand soldered (GASP!) through hole
components assembled. Will the PCB remain solderable for hand soldering
after 2 reflow cycles? Again, I expect bare copper in places since the
solder will not naturally flow out to cover all surfaces of the hand
soldered pad, top and bottom, especially after two reflow cycles.
Thanks!
Lang
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