| | Earl said, in essence: | | | | | Justin is absolutely right ... | | | | | | Again, Entek is not much more than a flux coating ... | | | | | | Metallic coatings protect best, as we all know - especially those electroplated. Those coatings chemical come in next to no coating at all under the right/wrong conditions. | | | | | | | Moonbert: Welcome back, it seems like you never left. | | | | We know of your history of being HASL-retentive. So, how do white tin protectants (Omicron & Dexter) fit in your schemes of electroplated metal superiority? The other day, I saw some really neat SEM pictures pointing-out the simlarities between the intermetallics of HASL and Dexter's "what ever they call it." | | | | TTYL | | | | Dave F | | | Moonbert? Never been called that before. Coming from you Dave, I don't give a damn, but then I really don't give a damn anyway. | | White tin is tin. Tin oxidizes readily. How readily? I don't know and I'm not prepared to find the answer. | | We're transitioning to OCC/OSP on some of our 1500 assemblies. We use gold on R/F and it often works. We use HASL - Uhg! Hell you cited my feelings about this stuff, but I must tell you how our Fuji's hate it now. Another reason to dump the stuff as its fiducial topography isn't easily recognizable to any known camer system. | | Do you have any information about the white stuff? | | Earlbert | Earl: The nice parts about OCC/OSP are it�s flat and it�s cheap. We're just kickin tires on white tin.
A 5000X SEM of immersion tin plating (like on the end-caps of the million or so ceramic caps each of us have put down in the last couple years) shows this crystal structure, lots of flat, irregular, pointy grains. And it�s from the points that the dreaded tin whiskers grow (or is it the dread yellow snow from where the huskies go?) This stuff is gray tin. White tin has a completely different grain structure, which looks like polygons under SEM � less likely to whisker??? SEMs of solder connections show similar imtermetalics between HASL and white tin.
Compared to HASL:
OSP
1 Drop in replacement for HASL at assembly - NO 1a Fluxes (SMT and wave) - NO 1b Reflow processing (Air, N2 profile) - NO 1c Storage handling - NO 1d In circuit test - NO 2 Have at least a 6 month shelf life - YES 3 Cost the same or less than HASL - YES 4 Provide flat/planar pads - YES 5 Be compatible with complaint pin technology - YES 6 Meet Bellcore and reliability criteria - YES 7 Be compatible with existing fab process - YES 8 Be readily available - YES
ENIG
1 Drop in replacement for HASL at assembly - MARGINAL 1a Fluxes (SMT and wave) - YES 1b Reflow processing (Air, N2 profile) - YES 1c Storage handling - MARGINAL 1d In circuit test - YES 2 Have at least a 6 month shelf life - YES 3 Cost the same or less than HASL - NO 4 Provide flat/planar pads - YES 5 Be compatible with complaint pin technology - NO 6 Meet Bellcore and reliability criteria - NO?? 7 Be compatible with existing fab process - YES 8 Be readily available - YES
White Tin
1 Drop in replacement for HASL at assembly - YES 1a Fluxes (SMT and wave) - YES 1b Reflow processing (Air, N2 profile) - YES 1c Storage handling - YES 1d In circuit test - YES 2 Have at least a 6 month shelf life - YES 3 Cost the same or less than HASL - YES 4 Provide flat/planar pads - YES 5 Be compatible with complaint pin technology - YES 6 Meet Bellcore and reliability criteria - YES 7 Be compatible with existing fab process - YES 8 Be readily available - NO
That otta get the nitpickers out there going ...
This was pulled from a "Future Circuits International" (whatever that is ... ) article. Call:
Florida CirTech (800) 686-6504 Mike Scimeca (President) Stephen Wentz hihat44@aol.com Dexter Industry CA 626.968.6511 fax 336.0160
Bottom line: White tin costs about the same as HASL. So even with the assembly process limitations of OSP, low material cost is a powerful driver for wide-spread acceptance in all applications, not just those requiring planar pads. Leading to volume driving down costs, providing resources for product/process improvement bla-bla-bla
So Earl, have you gone honest and haken a real job or is this a consulting project?
TTYL
Davebert
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