We build a lot of "developmental type" boards in quantities of 100 - 1000.
At these quantities highly automated test and repair is not cost effective.
Reference designators are quite useful to engineering, test technicians,
and for field repair. Aside from component location, the clear
identification of test points, LED indicators, test connectors is useful.
This step is also used for board level labels and warnings (floating
voltage, laser emission etc.). I have seen "tick marks"  placed near every
5th or 10th fine pitch pin to aid in pin location.

A test technician gave me a good analogy: "On your next vacation imagine
using a map but having no road signs".

I have no doubt that given proper volume, maturity, and automation,
eliminating reference designators can provide real cost savings.


Nat Perkinson
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>Questions on reference designators ?
>
>For those of you that have them screened or otherwise marked on you board;
>what do you use reference or component designators for in today's technology?
> I have found a few people who use them on a unloaded board to check
>first-piece if no overlay is present h them.  Some say it is for orientation
>and others say it is for rework or field repair.  With cost of screening
>reference designators on the board running between 2 and 8% of the cost,
>there must be a better reason
>
>Phil Hinton
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>
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