Graham,

There should be a note on the fabrication drawing that indicates that 
all hole sizes are after plating unless otherwise specified. IPC-2221 
provides guidance on how to select a hole size to meet a component lead 
requirement which would be a finished hole size. The fabricator selects 
a larger drill size to compensate for the amount of plating, or other 
finish, in the hole.

Regards,

Gary

Graham Collins wrote:
> Hello TechNet
> A question about through-holes on a flex.  We are having some debate about how to interpret a drawing.
> 
> Specifically, if I have a drawing that says:
> 1) fabricate per IPC 6013 type 4
> 2) tin-lead plating shall be per IPC 2221, method optional
> 3) hole size is specified in the drill schedule as 0.028", plated, +- 0.003"
> 
> Our debate is about the hole size after plating.  Does the +- 0.003" apply to the solder coated hole, or is that a copper only size?  Does IPC-2221 specify any maximum solder thickness?
> 
> I'm an assembler, so unfortunately I don't have these two IPC specs at hand.  
> 
> regards,
>  
> Graham Collins
> Halifax Production Engineering
> (902) 873-2000 ext. 6215
> 
> 
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