Hi there:

The IPC-2221 is assuming that you have process chemistries that aren't a
problem in terms of leakage current. There are some residues that will cause
dendrites or high leakage currents at the IPC-2221 dimensions. There are
also others which won't.

If you need to reduce track spacing use SIR to validate your process
chemistries at the track width/voltage you need. Bear-in-mind that the track
spacing can be greatly reduced if a conformal coating is applied.

Voltage gradient of 100v/mm would seem more appropriate. However, the
general thought was that we drive the failure mechanism by high voltage,
whereas recent research is proving that low voltage actually results in far
lower SIR between the tracks.

Confused? Tune into the next episode of SOAP (SIR On A Process!:-)

Regards,
Alan Brewin & Graham Naisbitt

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Concoat Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL UK

Tel: +44 (0) 1276 691100  Fax: +44 (0) 1276 691227
----- Original Message -----
From: KK Chin <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, June 21, 1999 5:56 PM
Subject: Re: [TN] IPC-2221 Conductor Spacing - More Questions


> Dear Technetter,
>
> Graig asked a very good question. I actually experienced problem following
the
> IPC-2221 table 6.1. Analytically, 0.6mm spacing in column B2 for 100 volt
seems
> too aggressive when the SIR test (IPC-TM-650 para 2.6.3.3 with coupon
IPC-B-24)
> guarantees up to only 50V for 0.5mm. Practically we also saw problem with
the
> 100V/0.6mm voltage gradient but our present findings have not been
conclusive
> yet.
>
> My question is, is the IPC-2221 voltage spacing really in conflict with
the SIR
> test?
>
> Graig, my apology for opening another can of worms without answering your
> question.
>
> K.K. Chin
> Artesyn Technologies
> Fremont, CA
>
>
>
>
> Craig Hillman <[log in to unmask]> on 06/18/99 03:00:00 AM
>
> Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please
respond to
>       Craig Hillman <[log in to unmask]>
>
> To:   [log in to unmask]
> cc:    (bcc: KK Chin)
>
> Subject:  [TN] IPC-2221 Table 6.1 Conductor Spacing
>
>
>
>
> I was wondering if anyone could provide me with information on the
> research used to determine the conductor spacing requirements of
> IPC-2221. More specifically, why is it not material dependent and
> is there a safety factor provided in the spacing determination?
>
> Any help would be greatly appreciated.
>
> Thanks in advance,
> Craig Hillman
> University of Maryland
>
>
>
>
>
> Dr. Craig Hillman
> CALCE Electronic Products and Systems Consortium
> University of Maryland
> College Park, MD  20742
> (301)-405-5316
> [log in to unmask]
>