Mike,

It depends.  Primarily what ever is on the drawing is what counts.  The 
drawing should be explicit; .062" over laminate, or .062" over metal.

The call out over metal is usually used to keep the overall component 
height under control.  The call out over laminate is usually used when 
card guides are used.  Many design must control both, so both are 
seperately called out on the drawing.


Raw materials are called out both ways.

Innerlayer materials are called out by the laminate thickness, ie .008" 
thick laminate is .008" with no copper on it.  

Thicker material, such as .062" material, includes the copper.  It is 
.059 without the copper on it.  

Confusing?  Yes.  

To your debate:
Given the requirement ".062 total laminate thickness", I would measure 
over the laminate only.

Given the requirement ".062 total board thickness", I would measure over 
the metal.


George

On Jan 20, 11:17am, Mike Gnieski wrote:
> Subject: Multi thickness
> Could someone settle a debate? What is the
> correct measurement of the total thickness
> of a multilayer board, glass to glass or
> copper to copper?
> 
> thanks
> Mike Gnieski
> 
> [snip]
>-- End of excerpt from Mike Gnieski



-- 

George Franck Jr
Raytheon E-Systems
Falls Church Va.

"The opinions expressed are those of the author, and are not necessarily those of the Raytheon Corporation."

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