Hello,
 
I have a question that someone may have had some experience with, my PCB's are fabricated to IPC 6011 / 6012 class 2 as per IPC-A-600. 
Question is on the minimum conductor width, the standards define & measure the minimum width of the conductor at its base (IPC-A-600 Section 3.2), but in the case of a fine pitch surface mount pad (I'm assuming conductor as defined in IPC6012 Section 3.5.1 - relates to both traces & surface mount lands) its possible to have the measurement at the base of the device within spec yet the etching process can reduce the width at the surface of the land by so much that there are serious assembly difficulties, I've seen variations of between 10 & 50% reduction on the surface of the lands between different batches. I'm aware that this is usually only an issue when there is a combination of fine pitch & heavy copper, my proposed solution it to tighten the spec to specifically state that the point of narrowest conductor width can not reduce below in my case 25%,  I'm wondering has anybody else had a similar experience & if so what was the approach to resolving it ?

Thank You.

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