Poh Kong Hui;

>From the information that you supplied, it looks like the fabricator wishes
to make the board using foil lamination, as opposed to core lamination. With
foil lamination, he uses a core of laminate material clad on both sides with
copper. He then applies two sheets of prepreg (semi-cured epoxy/glass
sheets) to each side of the core, and finally caps both sides of the
structure with copper foil sheets. With core lamination, he uses two double
clad laminate cores and "glues" them together with some prepreg sheets.

Either of these constructions should yield an equal product. Cost
differences are obsorbed by the fabricator and are transparent to the buyer.
Foil lamination represents a slight cost savings to the fabricator.

There should be no affect on the assembly process. 

As far a knowing the copper thicknesses, your illustrations do notindicate
any. Normally it would be specified in the illustration, for each layer, or
in a note on the drawing.




At 12:29 AM 5/10/96 +0800, Poh Kong Hui wrote:
>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]
>
>
Regards,

Gary Ferrari
Tech Circuits
(203)269-3311
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