I have never really seen post drill bake cure or eliminate the anomaly pink ring. Although some may view pink ring as a strictly cosmetic defect, there is a fine line between pink ring and actual delamination from the inner layer surface. In most cases the root cause of the pink ring is the fracture of the epoxy interface due to incorrect feeds/speeds in the drilling operation. This fracture then allows chemistry to wick back and remove the black oxide treatment from the inner layer. If the fracture is severe enough... there is the potential for a dreaded defect referred to as "WV's" (wedge voids). The post dip processes of today can band-aid a great deal of this problem but not all. Terry Pearo Marcel Electronics, Int. ______________________________ Reply Separator _________________________________ Subject: Re[2]: Post Baking Process Author: [log in to unmask] at Internet Date: 1/27/97 3:50 PM Will someone please clarify the paragraph below ? It states that pink ring can be eliminated with a post drill bake. It then goes on to say that it cannot reseal the crack and it is only a cosmetic fix. Isn't pink ring a cosmetic issue? Why would it be a dangerous fix if it works?? Also, you can have the best innerlayer treatment out there and if the drilling operation is unoptimized, it will not make a difference in cracking of inner layers. ______________________________ Reply Separator _________________________________ Subject: Re: Post Baking Process Author: [log in to unmask] at corp Date: 1/27/97 11:46 AM Post-drill bake - A bake after drill has been shown to eliminate pink ring. Our work shows this is a dangerous fix. Pink ring is caused by a chemical attack on innerlayer surfaces that are exposed by cracks introduced at drill. The bake relaxes the epoxy enough to close the crack, but it cannot reseal the crack. Thus it is at best a cosmetic fix. However in addition, the bake hardens epoxy smear and makes it difficult to remove. A much better solution to pink ring is to use a good innerlayer surface treatment that prevents cracking at drill. *************************************************************************** * 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. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * *************************************************************************** *************************************************************************** * 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. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************