Hi Ramon, I don't know which pictorials you are looking at, but there is a number of ways to make microvias in non-glass reinforced dielectrics (like liquid dielectrics, RCC, polyimide film and Thermount) using plasma or chemicals (hot NaOH or KOH). There is also photo-sensitive dielectrics. When you consider that the microvias in flex-circuits for inkjet cartridges are all etched rather than laser drilled, there must be more etched microvias than laser drilled ones in the world. The IPC Standards 2315 and 2226 show about 8 different ways of making small vias in dielectrics. Glass is one of those materials that is very difficult to dissolve, hence a lot of dielectrics are not glass reinforced. Happy Holden Westwood Associates "Dehoyos, Ramon" <[log in to unmask]> 12/17/2003 09:55 AM To: "TechNet E-Mail Forum." <[log in to unmask]>, [log in to unmask] cc: Subject: RE: [TN] sequential build up process Happy: The vias in the pictorials seemed to be etched instead of drilled. If that is the case, what kind of chemical etches glass and epoxy? Regards, Ramon --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------