Adb ul-Rahman,
        sometimes you make me laugh because your thoughts, although written
differently, are identical to mine.
        You stumbled onto the same conclusion that I had, these charts do
seem to be for finished laminate not prepreg. Then one must wonder about
what was being checked for stackups if a main component was missing
(prepreg)?
        Mark, do you have one of these stackups in electronic form? I would
be interested in seeing what you fabricator does for this as compared to my
contact with other fabricators.

        My take on the Drill column was that it was a general rating for
drilling of the material. Better, 'blank' & worse.

        I believe that I have just found a glaring technical error in the
charts for FR4 and High Tg FR4. Notice how there are absolutely no
differences in the Dk across the two sets of materials? My experience tells
me that this is impossible, different Tg = different resin, different resin
= different Dk, I have never seen the same Dk spec from any manufacturer
across their regular or high Tg rated materials, there is always a variance.
Seems somebody at IPC might have taken a shortcut instead of actually
researching their materials.
        See even the IPC knows that nobody is actually supposed to read all
their material. 8^>

Brad Velander,
Lead PCB Designer,
Norsat International Inc.,
#300 - 4401 Still Creek Dr.,
Burnaby, B.C., V5C 6G9.
Tel. (604) 292-9089 direct
Fax (604) 292-9010
website www.norsat.com


> -----Original Message-----
> From: Abd ul-Rahman Lomax [mailto:[EMAIL PROTECTED]]
> Sent: Monday, July 09, 2001 3:45 PM
> To: Protel EDA Forum
> Subject: Re: [PEDA] Layer Stackup Info.
> 
> 
> At 09:21 AM 7/9/01 -0700, Brad Velander wrote:
> >Mark,
> >         I read your comments and went to my IPC-2222. I am 
> no IPC expert by
> >any stretch but aren't the tables you specify (4-2 ... 4-6) 
> only for copper
> >clad laminates, where are the prepregs? 
<SNIP>
> 
> However, if you read the specification several times, you 
> might notice that 
> 4.3.6 explains that the tables "provide information on the 
> properties of 
> finished bare laminates for different prepreg constructions. 
> To establish 
> final laminate thickness with copper, add 35 um for each oz. 
> of copper on 
> the laminate."
> 
<snip>
> 
> By the way, looking into this made me realize that the tables cover 
> laminate, not prepreg. There are other specs for prepreg, 
> IPC-L-109 and 
> IPC-4101. Full employment for IPC staff!
> 
<SNIP>

> What DRILL means in this chart I find obscure.
> 
<SNIP>
> 
> [EMAIL PROTECTED]
> Abdulrahman Lomax
> P.O. Box 690
> El Verano, CA 95433

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/leave.html
*                      - or email -
* mailto:[EMAIL PROTECTED]?body=leave%20proteledaforum
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Browse or Search previous postings:
* http://www.mail-archive.com/proteledaforum@techservinc.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

Reply via email to