I always thought the reduction was to allow for component terminations and lead protrusion. I could be wrong. This spec was adapted from Mil-D-275. Sometimes things got lost in the translation, but mostly when trying to include some provision for Class 1 or 2 products. I don't think the table was compromised. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Brinkman, Mark Sent: Friday, September 23, 2005 11:56 AM To: [log in to unmask] Subject: Re: [TN] IPC-2221 conductor spacing I'm just looking for answers, any opinion and/or analysis helps. Mark -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (AZ75) Sent: Friday, September 23, 2005 10:20 AM To: [log in to unmask] Subject: Re: [TN] IPC-2221 conductor spacing Do want a cross-section of public opinion on this or a Gap Analysis on the differences? Dewey -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Brinkman, Mark Sent: Friday, September 23, 2005 8:02 AM To: [log in to unmask] Subject: [TN] IPC-2221 conductor spacing Can anyone clarify why A6's clearances for non-conformally coated lands is less than B2's clearances for unmasked and non-conformally coated conductors? I would consider a land a conductor and thus I would think B2 applies to lands also. Also, I assume the polymer coating B4 references is solder mask and that it is only applicable when it covers the conductor and that solder mask between conductors does not factor into spacing i.e. solder mask between 2 uncoated lands doesn't allow the lands to be closer. Does anybody have any thoughts on this? Thanks Mark Brinkman Honeywell CES 23500 W. 105h Street, Olathe, KS. 66061 * 913-712-3104 * [log in to unmask] <mailto:[log in to unmask]> 7 913 712 1322 The enclosed unclassified technical data is being exported under License Exception "TSU" and is to be used solely by the individual/organization to whom it is addressed. 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