Yehuda: Polyimide boards are very hygroscopic, they absorb moisture very easily and quickly. It is the moisture trapped inside the board which rapidly expanded during your reflow process which caused your delamination and measle problem. As a matter of normal shop floor practice, we always bake polyimide boards prior to any reflow process whether it is reflow for surface mount and/or wavesoldering. Ideally, when the board cools to room temperature, the board is processed. For surface mount, the board is cooled, then screen printed and reflowed immediately. For wavesoldering, we bake the board with components in place, removed, allowed to cool approximately 30 minutes, then wavesoldered. You must be aware of what your relative humidity is at the time of soldering. If the relative humidity is greater than 75%, it may be impossible to relow since the board will re-absorb the moisture you have just baked out ! The process parameters generally speaking for baking range from 2.0 hours at 250F to 6.0 hours at 150F. (Note this topic has been debated for years, some feel that in order to dry properly you must bake over the boiling temperature of water. While others believe that board solderability is adversely affected when baking at higher temperatures. It is up to you to determine what drying profile you want to use. I've had success with all different ranges of settings, the important thing is to dry. Following these steps will eliminate all of your delamination and measle problems Bill Kasprzak Moog Inc. 716-652-2000 ext 2507 [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * 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] * ***************************************************************************