David Tandy: Our position at Zycon is that non-functional pads should be suppressed. Stack height at drilling is a function of the amount of copper within the panel (among ather things). In order to maintain the quality of the drilled hole, parts with non-functional pads present are drilled at lower stack heights. Since most board shops are constrained at drilling this results in a resistance to doing jobs with non-functionals present, especially when business is strong. As far as reliability and quality are concerned we have done extensive testing (through temp cycling) and find no evidence to support the position that non-funtionals improve reliability. In fact we have come to the same conclusion which Delco reached that on some more conservative designs that the opposite is true. Most of our testing however has been on 0.093" thick product drilled at 0.0135". [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Inner layer PAD Suppression or NOT? Author: [log in to unmask] at corp Date: 9/26/96 12:27 AM I am currently debating the pro's & con's of suppressing non-functional inner layer pads and have found our PCB fabricators have differing views on which is best. Here are the 2 views. 1. Suppressing inner layer pads will give a better drilled hole, and so will produce a more consistant & cleaner plated hole. 2. NOT suppressing inner layer pads will produce a stronger & more reliable PTH less prone to failiure. We first changed to using inner layer pads after a new design, which required 2 reflow soldering processes & 1 wave solder process, failed ICT afer assembly. The cause was a process problem at our supplier which resulted in via's cracking in the barrel. Having this problem made us consider what we could do with the design to reduce the risk of similar problems happening again. I would appreciate any views you may have on this topic. ________________________________________________________________________ | [log in to unmask] David Tandy. EDA Specialist. | | Tel: (+44) 161 486 1511 GenRad ADS, Monmouth House, Monmouth Road, | | Fax: (+44) 161 486 1989 Cheadle Hulme, Cheshire, SK8 7AY, England. | |________________________________________________________________________| *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************