Hi Chris,

Yes the issue was put in the parking lot because the supplier rarely has
access to the designer.  Unfortunately the buyer cannot answer these
types of questions.  When a contract manufacturer is involved, then
getting back to designer is about as tough as Toyota figuring out their
acceleration problem.

When companies provide an avenue for these type of discussions with
their designers, I am confident most suppliers will enter into an AABUS
discussion.

Randy
 
Randy Reed, CQE
Reliability Lab
Viasystems Group Inc.
[log in to unmask]
 
503.992.4421-direct  l   503.545.0150-cell

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Chris
Mahanna
Sent: Friday, March 12, 2010 9:25 AM
To: [log in to unmask]
Subject: Re: [IPC-600-6012] Edges and Crazing/Haloing

Hi Wendi,
This must be the topic of the month.  However, I think it has been
lurking since the resin starting getting more brittle.
The designers have a number that they are going to use and that's
unlikely to change.  The suggestion on the 6012 call was to explicitly
lay down AABUS rules for the fabricator and design activity to sit down
and figure out if minimum dielectric spacing between biased conductors
has been violated by the observed or expected haloing.  Unfortunately,
as far as I remember, the issue was put in the parking lot.
Chris

-----Original Message-----
From: IPC-600-6012 [mailto:[log in to unmask]] On Behalf Of Wendi
Boger
Sent: Friday, March 12, 2010 11:11 AM
To: [log in to unmask]
Subject: [IPC-600-6012] Edges and Crazing/Haloing

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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