John
 
Here is an example where the spacing to the edge contacts, that do not get beveled, are only 0.007" from the board edge and there was haloing that measured about 0.004" in depth and the customer wanted to reject the product based on the IPC criteria.  I think the new language contradicts itself by stating "50% of the distance from the edge to the nearest conductor" and then "The distance between the haloing penetration and the nearest conductive feature shall not be less than the minimum lateral conductor spacing".  This design specified a minimum spacing of 0.005" and the haloing was within about 0.003".  This product would still be rejectable.
 

 
Thanks,
 
Scott A. Bowles
Director of Engineering and Quality
Hallmark Circuits, Inc.
13500 Danielson Street
Poway, CA 92064
 
858 513-2200 Office x8848
858 513-2233 Fax
858 437-7827 Cell
 
 
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-----Original Message-----
From: John Perry [mailto:[log in to unmask]]
Sent: Sunday, March 14, 2010 1:06 PM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Edges and Crazing/Haloing
 
Jack and All,

We used to say the following in 3.3.1, Edges, in IPC-6012B:

3.3.1 Edges - Nicks, crazing or haloing along the edge of the board, edge of cutouts and edges of nonplated-through holes are acceptable provided the penetration does not exceed 50% of the distance from the edge to the nearest conductor or 2.5 mm [0.0984 in], whichever is less.

Now IPC-6012C will say the following:

3.3.1 Edges - Nicks or crazing along the edge of the printed board, edge of cutouts and edges of non-plated holes are acceptable provided the penetration does not exceed 50% of the distance from the edge to the nearest conductor or 2.5 mm [0.0984 in], whichever is less. The distance between the haloing penetration and the nearest conductive feature shall not be less than the minimum lateral conductor spacing, or 100 µm [3,937 µin] if not specified.

Regards,

John Perry
Technical Project Manager
IPC - Association Connecting Electronics Industries®
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: Friday, March 12, 2010 3:25 PM
To: Listserv IPC-600-6012
Subject: Re: [IPC-600-6012] Edges and Crazing/Haloing

The guideline for edge to hole is in IPC-2222, not IPC-2221
in IPC-2222 10.1.1 it says board edge or unplated hole to conductor
shall not be less than Table 6-1 of IPC-2221 plus .4mm
(and Table 6-1 is your minimum clearance based on voltage)

The MINIMUM from Table 6-1 (.05mm) plus .4mm works out to 17mils!

The discussion you remember was regarding IPC-2222 requirement
for haloing, and I'm not sure it was ever resolved, but I remember
we DID change some wording for the next revision.
You could get the new changes from John Perry for your own interest,
but of course it won't mean much until it is officially published.

And the haloing rule it won't help if your designers are disregarding the
clearance guideline, but I'm sure you know THAT (grin)
good luck!
Jack
On Fri, Mar 12, 2010 at 10:11 AM, Wendi Boger <[log in to unmask]> wrote:

> Everyone,
>
>
>
>   I seem to remember a discussion about Haloing of edges and non plated
> holes at one of our recent meetings.   The requirement for the haloing
> to be less than 50% the distance to nearest conductor works assuming the
> design has a reasonable space from conductor to edge.  I looked in
> IPC2221 but did not find a guideline for suggested minimum distance.  We
> are seeing non-plated tolling holes with surface ground rings at <10mils
> hole edge to copper.  Depending on the material and hole size it's
> difficult to meet the 50% rule.
>
>
>
>   Is there a section in 2221 I can send the designers to so we can
> avoid this type of issue?
>
>
>
> Thanks,
>
> Wendi Boger
>
>
>
>
>
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