1) Historically, the "red" or "brown" oxide were developed in part to use on polyimide materials, since the very long crystalline structure of the "black" oxide leads to fracturing because of lap shear stress induced when the panel cools after the relatively high laminationand post-bake temperatures used with polyimide. The only real difference between "red" oxide and "black" oxide is in the concentrations of the caustic and oxidizer; the actual chemicals are the same. A reduced oxide also works just fine for polyimide, as long as you are using a reduced "red" or "brown" oxide formulation. 2) Despite what an earlier posting has said, although permanganate (when used in conjunction with a sweller, either a butyl-caustic or a pyrol-type) works VERY well for conventional polyimide, the MDA-free polyimides are not attacked very well by a permanganate process. If etchback is required, it will be almost mandatory to use a plasma. It is common to follow plasma with permanganate to get the surface microroughening that plasma has difficulty in providing. 3) SEMs will be required to verify roughening of the resin. Once again, topography will be a real challenge if using MDA-free polyimide. Fred J. >>> Deron Pirie <[log in to unmask]> 05/25/98 09:08am >>> can anyone help me please, i have some questions concerning polyimide pcbs :- 1/ what type of inner layer oxidation is recommended / suitable for polyimide e.g. black, brown, red, reduced etc. ? 2/ what type of hole desmear is recommended / suitable for polyimide ? 3/ we have produced some trial pcbs and are getting slight hole wall pullaway - any ideas as to what might be causing this ? best regards, deron pirie. Deron Pirie Irlandus Circuits Ltd. ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################