Myron, Part of your explanation of the defects sounds like a material problem and part sounds like a processing problem. Some of the items listed appear contradictory. Whose material are you using/getting? You say that the affected areas "usually surround barrels or via, and at times span several innerlayers between barrels and/or via". If they are associated with the barrel of a hole they are probably not material related. Laminate and Prepreg can't tell the difference between where holes will be and where they won't be. Also, If they span several layers the defects you describe could not form a continuous bridge across both laminate and prepreg layers. Are the defective areas touching the barrel of the hole? Or, are they merely surrounding it in the clearance areas of the ground planes? Are the distortions in the inner layers all moving in the same direction? Say, towards the bottom or top of the board? Does it look like the holes were punched instead of drilled? If either one of these is the case it sounds like you have a drilling problem possibly compounded with some other issue. You'll have to give more info. Dan Howell Zycon ______________________________ Reply Separator _________________________________ Subject: Innerlayer defects. Author: [log in to unmask] at corp Date: 9/5/96 5:48 AM We are looking for an explanation as to the cause of defects found in some areas of a PWB laminate. The affected areas were observed in microsections of an assembly to have the following characteristics. 1. A dramatic difference in the color and pattern compared to the rest of the innerlayer material. Defective sections are of a very light color, and are almost completely translucent. Only small traces of the usual weave pattern are seen there. 2. The affected areas usually surround barrels or vias, and at times span several innerlayers between barrels and/or vias. 3. Although the sides of the barrels are somewhat distorted, no cracks have been seen in the plating. 4. Distortions in the geometry of innerlayer traces are seen around the affected areas. 5. After one of the microsections was prepared, a probe was touched to one of these areas, and the laminate felt soft. In time it became hardened. The assembly was microsectioned because of intermittent resistive paths between certain nodes and either ground or Vcc. At times, following chamber testing, the paths had alternated between the nodes and ground or Vcc! Thank you for any suggestions. Myron Papiz MSL *************************************************************************** * 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. * ***************************************************************************