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Re: assembly layer

 

nnn brings some good points, but let’s get realistic.
Assembly documentation is more and more in digital form and paper is slowly disappearing from the manufacturing floor.
We need to look at their value in different process steps.

1- SMT Assembly drawing has ZERO value there, except in the inspection step where often a high resolution picture of a Known Good Board is used for human inspectors when automated vision inspection is not available.
2 - TH automated step is now very similar to SMT (highly automated), but parts are larger in size so it is less of an issue to have RefDes near or inside the part outline.
3 - Hand Insertion is the last place where Assembly Drawings have a value, and there you need only a small portion of the board. Assembly people do not look at values, they need pictorials to identify the right part.
Part value is for the technical staff, but not for the manufacturing staff (I will put Test peoples in the technical staff).

Keep in mind that dense SMT boards have very little room for RefDes, and it is always a struggle between Designers (who want none, only room for layout) and Manufacturing (who want ALL RefDes).
The balance is hard to maintain as there is simply no room to place a readable RefDes near an 0402 or worse 0201 and smaller.

So to summarize, Assembly layer should have RefDes (Reference Designator) and an outline of the part.

My $0.02,
Jean-Paul
AC9GH





 

> On May 24, 2015, at 8:26 PM, Carl Poirier <carl.poirier.2@xxxxxxxxx> wrote:
> 
> you



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