Folks, I may be fooling myself, but this subject is important. As I have reached the maximum level of the Peter Principle, I really have nothing more to say on the subject. However, the following is a response to several off line responses to the subject: I agree with all your are saying. All I've been saying, throughout the long IPC postings on this subject, is that selecting a high Tg material, for its sake alone, is not the way to go. If needed, certainly use it, if one is aware of its benefits or detractions. However, all other process requirements must be met as well. Certainly, as we have agreed before, Cu plating thickness, though getting thinner, and ductility (not being assured, in my opinion, adequately with respect to the former) must be ensured as well - especially in these ever increasing higher aspect ratio holes. I know Ervin was trying to make this point as several others said to me offline as well. Today's plating chemistry and processes still have a way to go, so material alone is not going to do it. Also, I have said, Tg only assures more time before hole wall and associated anomalies, or the reverse, develop. It may take 30% more time for polyimide to come apart than an high Tg epoxy, but come apart it will over time. We've all seen TMA and DSC evidence graphically (I will post one on Steve's site if requested) showing this consistently as the temperature is applied over time, as expansion takes place, before destruction at or about the rated Tg. We all know this is because the PPM/C Z-axis expansion rate is about the same for all materials using reinforced resin systems as epoxies, BT's, and polyimides. Therefore, hole walls, and associated anomalies, coming apart must be prevented at the design and process levels. Simply choosing a high Tg material won't get the job done. As for the solder floats, and very serious pre-conditioning requirements, 550 for 10 thermal stress, notwithstanding serious thermal shock testing, is pretty severe even today. This is true though some manual soldering processes see higher temps, times usually are much shorter. Most certainly recognize that, even though a soldering iron's tip temperature may be as high as 800 degrees, it isn't brought to bear on the solder termination areas for anything approaching 10 seconds. Hardly anything survives these temps for long durations. As you, and many others, have said before, you must get on an off in a time consistent with effecting a quality solder joint - unless you are seeking destruction. Based on my personal email, and others, we would all appreciate your input, like this, to be on the TechNet forum. I may be wrong, but it seems very important stuff to a lot of people seeking this type input. Also, I'm surprised not to see more of you folks, who have spent so much time and effort developing all these incredible standards and specifications (especially the 6010 series), attending this subject. They, unlike some plated holes, just keep getting better. I, and others, must be missing something, or it isn't that important after all. Earl Moon --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------