Dear Joseph;

I am afraid it may not direct answer for your question, I would like to introduce
how we Japanese flex circuit industry use these words.

I understand the both have the same meaning.

We often say or write "coverlay" or "overlay" as one word rather than cover lay or
over lay. Now, coverlay is more popular and often used than the use of overlay.
However some engineer or manufacturer may prefer to use overlay as his custom.

In our Japanese Industrial Standards, in JIS C 5606-1993, the formal international
standard corresponding to this standard is IEC194(1988), we also have no defenition
for "overlay".

In JIS C 5603-1993, coverlay is noted as below.

Coverlay; Film covering the conductive portion of a flexible printed wiring
board(PWB) for insulation protection. Remarks: Film has been removed from the
conductive part necessary for connection, such as land and terminal.

I guess they are what over lay also means.

At last, I have to add all these JIS in english version is possible to be found in
your IPC/JPCA-6202 standard, named "Performance Guide Manual for single- and
Double-Sided Flexible Printed Wiring Boards"
I recommend you to obtain this IPC standard for your further understanding for flex
circuitry.

In my personal opinion, IPC-T-50F should be re-considerd among the US and Japanese
PWB industries. The term 'over lay' may be added as the Remarks for 'cover lay'
because it sometimes used as the same meaning.

Toru Koizumi


Joseph H. Smith  wrote:
>     Pertaining to flex circuitry,  I see that 'cover lay' is defined in
>     IPC-T-50F.  I have now come across the term 'over lay' which is not
>     defined.  Can anyone please explain?
>     Thanks

----
Fujikura Ltd.  [log in to unmask]

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