I tend to agree with John here, I do not have silkscreen outlines or names for 99% of my SMT components.
They are all dealt with by SMT assembly drawings.
IMO there is no reason for most of them to be there, why would a SMT component need any outlines etc?
It's a machine that is placing them so it does not need to see where they go, boards are usually too
dense to be able to put component names on for them all & if you cannot get them all on then there is no point in putting just what can fit as a drawing of the others will be needed anyway.
Only PTH components that are manually added or are changed during the boards life need legend, board idents and connector etc do too.
Although legend on pads is really the PCB designers problem/fault, not the board houses.
If the person that does the board leaves legend on pads & does not check for it then it's their fault
and no one else's, and putting a disclaimer on a document is just a way of weaselling out of doing it right in the first way.
You can easily just take the Gerber layer for the SMT side solder resist and copy that to be a copper scratch layer though.
Matthew Lamkin
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of John
Parsons
Sent: Tuesday, February 06, 2007 11:07 PM
To: [log in to unmask]
Subject: Re: [DC] Silk Screen Verification
Foolproof! Not sure if there is such a thing;
- Eliminate the use of screen printed legend unless you really, really need
it. Most boards are so dense these days that it is next to useless anyway.
- Train your CAD librarian or whomever to design proper footprints/outlines
to begin with.
- If it really is an ongoing issue with your fab shop, find another
- Legend on SMD pads is an IPC violation so if you are spec'ing a build to
IPC requirements then, as with the note suggested below, you have a case for
an RMA but this is the last course of action you would want to take as it
costs everyone involved time and money.
Good luck,
John
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