I'm sorry, I re-read your message and realized I didn't give you a complete answer.

I would not expect there to be significant differences in processing or assembly.
The thickness,  over copper, after lamination (before plating) is 1.471mm versus
the 1.511mm thickness your fabricator is suggesting.  Both constructions should 
provide flat, stable, reliable PCBs.


On Thu, 9 May 1996 09:29:52 -0700 Poh Kong Hui wrote:

> From: Poh Kong Hui <[log in to unmask]>
> Date: Thu, 9 May 1996 09:29:52 -0700
> Subject: Re: FAB: PCB Fabrication Drawing.
> To: [log in to unmask]
> 
> Dear Technet,
> 
> I hv an issue with a 4-layers boards. I am not sure what my customer's
> requirement, because I am not familar with PCB fabrication. Pls escuse me. 
> >From the fab diagram, this is one of the drawing what being showed.
> 
> 
>         Customer's Requirement:            ______________
>                                                 0.4
>                                            --------------
>                                            |    0.6     |
>                                            -------------- 
>                                                 0.4
>                                            --------------
> 
> 
>         PCB supplier's recommendation:     ______________
>                                                0.11 x 2
> --------------
>                                            |    1.0     |
>                                            --------------
>                                                0.11 x 2
>                                            --------------
> 
> Could anybody can explain to me what it means ? And what the differecnce
> between the cust's requirement & the supplier's recommendation in term of
> board processing and also when come to PCB assembly.
> 
> And could anybody tell me how to determine the PCB inner & external copper
> thickness. I realise some of our boards, of same model, but differ in 
> weight & thickness, and sometimes twist after reflow from batch to batch.
> 
> Thks and Regards..           
> 
> Poh Kong Hui 
> Nera Electronics
> Email: [log in to unmask]
> 
Fred J. Paul, Sr. Process Engineer
PCB Operations, FLUKE CORPORATION
direct:  206 356-5734  fax:  206 356-6070
[log in to unmask]