Jack,

        One reason is that specs can change and that might impact your 
design.   For example, the default minimum spacing (lateral spacing) 
requirement was changed with the recent 6012 revision so that it now only 
applies to metal cores.   So instead of a default lateral spacing value of 
.004 inch, we are left with only a reference to spacing tolerance, which 
is 70% of the design minimum.   Anyone that did not list a minimum spacing 
value on their print and counted on the .004 inch default, is affected by 
this change, unless the minimum spacing in their design happens to be 
.0057 inch.

Lance




From:
Jack Olson <[log in to unmask]>
To:
[log in to unmask]
Date:
02/24/2011 10:50 AM
Subject:
Re: [IPC-600-6012] Document Sets
Sent by:
IPC-600-6012 <[log in to unmask]>



I have a follow-up question.

What led me to writing that last post was that I have collected many 
samples
of fab drawing notes as part of my working with the IPC-2610 series
committee, and I noticed that the MAJORITY of them call out both IPC-6011
and IPC-6012, so I thought I was onto something.

I' m trying to figure out why people are specifying things that are 
already
part of IPC-6012. For example, many people have a Bow and Twist note on
their fab drawings, but the maximum allowance they are calling out exactly
matches the one in 6012 (which in my mind, if its already in there, you
don't need to call it out separately, right?)

So my follow-up question is:
"Why do people do that?"

Jack


.
On Thu, Feb 24, 2011 at 11:17 AM, John Perry <[log in to unmask]> wrote:

> Hi Jack,
>
> I believe the words you are looking for in IPC-6012C are in section 3.1,
> General.  Here is the reference to meeting the generic requirements of
> IPC-6011.  So in the case of this document, the wording is a little 
farther
> in than the other documents, which has such language in section 1.
>
> John Perry
> Technical Project Manager
> IPC - Association Connecting Electronics Industries(r)
> 3000 Lakeside Drive # 309S
> Bannockburn, IL 60015-1249 USA
> +1 847-597-2818 (tel)
> +1 847-615-7105 (fax)
> +1 847-615-7100 (Main)
> [log in to unmask]
> www.ipc.org
>
> -----Original Message-----
> From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Jack Olson
> Sent: Thursday, February 24, 2011 11:13 AM
> To: Listserv IPC-600-6012
> Subject: [IPC-600-6012] Document Sets
>
> I have a question about how document sets are structured, in particular
> comparing the 6010 series with others like 2220 or 2610 series.
>
> IPC-2222 specifically incorporates all of the generic IPC-2221 with this
> statement:
>
> 1.1 Purpose The requirements contained herein are intended to establish
> specific design details that shall be used in conjunction with IPC-2221
>
> IPC-2614 (for example) incorporates everything in the generic IPC-2611
>
> 3 REQUIREMENTS The requirements of IPC-2611 are a mandatory part of this
> standard.
>
> What this says to me is that the documentation only needs to call out 
the
> specific standard to get the requirements of BOTH the specific and the
> genericl standards.
>
> Logically I assume that the same holds true for IPC-6011 and IPC-6012, 
but
> in my latest copy of 6012C (PROPOSED STANDARD FOR BALLOT - JANUARY 2010) 
I
> don't see any wording like this. Am I losing my mind? Do I have to call 
out
> BOTH of them on my fabrication drawing?
>
> onward thru the fog,
> Jack
>
> ______________________________________________________________________
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