Good day! My QC Manager (also my boss) has concerns of heat dissipation to the plane if no thermal is used to connect SMT pads directly to the plane. This could lead to the cold or insufficient solder joints on some power and gnd pins. Has anybody had any problems or done any studies for this condition? What width traces are you using leading from the pads to the vias? How far is your via from the pad? Are you using any special precautions to prevent heat dissipation to the plane? Any information would be appreciated. I would like to thank the IPC and all the participants of this forum for there willing inputs and suggestions. I have picked up a great deal of information and ideas from your experiences and situations. Where else can we share ideas and get REAL life experiences to aid in our day to day battles! Many Thanks! Brandon Luther Dataram Corp. (609) 799-0071 x310 [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Re: Design (fwd) Author: [log in to unmask] at Internet Date: 9/17/96 2:16 PM We have been using vias without thermal pads for some time now, and have had no problem at all. To my knowledge our fab vendors did not even notice the difference. Due to our heavy use of smt, virtually all our boards are 100% or 99.99% surface mount, removing the thermal pad and connecting our vias directly to the plane improved the emi-esd characteristics of our boards. It has been a good deal all around. In addition to this, we have also reduced the size of our anti pads. We were having problems with signal quality due largely to "impedance bumps" which would occur when a trace passed a pad with a large anti pad. This was because as the trace would pass over the anti pad, it would suddenly not have a ground layer to associate to. To cure this problem, we have reduced our anti pads to a size where when traces pass by at minimum distance, there is adaquate coverage by the associated layer. my two cents worth... Ken Barrett Cisco Systems San Jose California ([log in to unmask]) **************************************************************************** * The 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. * **************************************************************************** **************************************************************************** * The 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. * ****************************************************************************