Phil,
I imagine the definition of JIS standard comes from typical Japanese single or double
sided Flex PWB, we often call it FPC, that prefer film type insulation materials to
achive repeated flexibility. Actually, we sometimes use screen printed overlay or
overcoat, however, our main material forcused for repeated flexibility would be coverlay
film, not covercoat ink. I understand the word "coat" would be not suitable to describe
film layer.
There are several words or terms in order to describe the material covering the
conductive portion of a flexible printed wiring board(PWB) for insulation protection.
Coverlay, overlay, covercoat, and overcoat so on... They are simular.
Maybe one reason why coverlay (or cover lay) became popular and fixed in our standards
would be because it can show both Film and Ink, maybe additional new type of protection
materials formed even by exposure and development method.

Toru Koizumi


Phil Dutton wrote:
>Joseph and Toru,
>I have also come across the term 'overlay' used to describe the screen
>printed legend on a PWB.
>Phil.
>
>At 10:54 10/09/99 +0900, you wrote:
>>Dear Joseph;
>>I understand the both have the same meaning.
>>
>>We often say or write "coverlay" or "overlay" as one word rather than
>>cover lay or cover 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 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.
>>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
>>
>
>Phil Dutton C.I.D.
>Senior CAD Technician
>IPC Certified Interconnect Designer
>Vision Abell Pty Ltd
>Second Avenue, Technology Park,
>Mawson Lakes.  SOUTH AUSTRALIA  5095
>
>Phone :                (08) 8300 4400 (reception)
>               (08) 8300 4481 (direct)
>Fax :          (08) 8349 7420
>email:                 [log in to unmask]
>Internet Page: http://www.vsl.com.au

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

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################