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When to use OSP surface finish for PCB?

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hal9001:
Is it ever better to use OSP instead of HASL or other surface finishes?
How does it behave in humid conditions during storage?


Cheers!

tszaboo:
HASL: For everything, except:
ENIGL: Fine pitch BGA or other requirements specifically ask for this
OSP: If you cannot afford HASL, or someone accidentally selected this on the order form.

hal9001:

--- Quote from: tszaboo on January 17, 2022, 01:46:03 pm ---HASL: For everything, except:
ENIGL: Fine pitch BGA or other requirements specifically ask for this
OSP: If you cannot afford HASL, or someone accidentally selected this on the order form.

--- End quote ---
Thanks. A vendor offers only OSP or ENIG for boards under 0.8mm. ENIG is more than two times the expense.
I read OSP finish uses chemicals instead of plating with another metal such as in ENIG or HASL. Does it scratch off if boards are stacked on top of each other for example?

xavier60:
OSP isn't cheap at all at PCBway, adds about 50% over leaded HASL. Annoying thing is that their HASL used to be acceptable, now it's too lumpy.
They chose to blame my PCB design rather than look for the real cause of the quality loss.
I like the OSP finish, very good solderability. I have yet to see for how long unused boards maintain their solderability.

tszaboo:

--- Quote from: xavier60 on January 19, 2022, 08:54:00 am ---OSP isn't cheap at all at PCBway, adds about 50% over leaded HASL. Annoying thing is that their HASL used to be acceptable, now it's too lumpy.
They chose to blame my PCB design rather than look for the real cause of the quality loss.
I like the OSP finish, very good solderability. I have yet to see for how long unused boards maintain their solderability.

--- End quote ---
OSP is expensive because it isn't their standard procedure. The process itself is used when you want to save on PCB production, when we are talking about thousands of boards.


--- Quote from: hal9001 on January 19, 2022, 06:21:45 am ---
--- Quote from: tszaboo on January 17, 2022, 01:46:03 pm ---HASL: For everything, except:
ENIGL: Fine pitch BGA or other requirements specifically ask for this
OSP: If you cannot afford HASL, or someone accidentally selected this on the order form.

--- End quote ---
Thanks. A vendor offers only OSP or ENIG for boards under 0.8mm. ENIG is more than two times the expense.
I read OSP finish uses chemicals instead of plating with another metal such as in ENIG or HASL. Does it scratch off if boards are stacked on top of each other for example?

--- End quote ---
That is a thin board. Usually the reason to go with thinner boards, is because you want to save space (eg smart phone) where everything else is small, and then ENIG is better.
In OSP they just cover the bare copper surfaces with a film, that evaporates during soldering. Kinda like flux.

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