As in the now obsolete MIL-S-13949, if the thickness is not to be
specified then it may be expressed in a generic format replacing the
four digit thickness ident such as "XXXX" (e.g.: ANSI/IPC
-L-108/04XXXXD1/D1AA3 specifies FR-4, thickness unspecified, double
treated electrodeposited copper, 1 oz, both sides, thickness tolerance
grade A, pits & dents grade A and quality class 3). A vendor, upon
reading this specification knows that the thickness is his call in
meeting the final PCB thickness specification on the fab drawing. Ditto
for the prepreg specification.
Chris Taylor
Senior Printed Circuit Designer
LXE, Inc.
125 Technology Parkway
Norcross, GA 30092
voice: (770) 447-4224 X3242
fax: (770) 447-6928
e-mail: [log in to unmask]
>----------
>From: Tom Kropski[SMTP:[log in to unmask]]
>Sent: Wednesday, February 18, 1998 9:38 AM
>To: [log in to unmask]
>Subject: Re: [DC] FR4 Material Part Number -Reply
>
>Those IPC specs seem like good candidates, so here's the next question.
>On a multilayer board, if the layer construction is not critical, do you
>still specify the core/prepreg thickness by part number or just specify an
>overall finished thickness?
>Interested to here others responses
>
>----------
>> From: Davis Ben <[log in to unmask]>
>> To: [log in to unmask]
>> Subject: Re: [DC] FR4 Material Part Number -Reply
>> Date: Wednesday, February 18, 1998 8:57 AM
>>
>> Larry Campbell wrote:
>> >
>> > I'm still waiting to hear an answer to the original question. If
>> > MIL-S-13949 is not called out on your fab drawing, then what
>> > replacement spec should be called out.
>> >
>> > Larry
>> >
>>
>>
>> Larry...
>>
>> We call out ANSI/IPC-L-108 for laminates and ANSI/IPC-L-109 for prepreg
>> material. Both have class and type designations. We still have some
>> programs that call out the MIL-S-13949, but I suppose that is because
>> the contract pre-dates the spec obsolete date.
>>
>> Ben Davis
>> Systems & Electronics, Inc.
>> [log in to unmask]
>>
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