Eric As you seem to be working with resist-on-copper, I suggest you use a copper chloride acid etchant, with replenishment of hydrogen peroxide according to the redox. This should cure your problem. Brian Eric Masters wrote: > > I am having some difficulty with dryfilm breakdown on heavy copper > etching. > I have tried a number of different films, and they all work on copper > weights > less than 3 ounces. Above three ounces, I begin to have breakdown > issues in > the etch replenisher chamber. > > I have maximized all the process parameters for dryfilm: surface > prep, > lamination exit temperature, exposure, and developing. I am convinced > that > the problem lies with the etching chemistry, but I'm not sure what > parameter > contributes most to breakdown. > > Does anyone know which component is the most troublesome? or is it a > combination of things? I've tried varying pH, copper concentration, > chlorides, and controlling free ammonia in the replenishment chamber. > Any > suggestions will be appreciated. > > Thanks. --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------