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Subject: Best order in which to expose 2 sided sensitized boards

From: "demers_barry" <sdad@...>
Date: 2010-02-11

Using, in this example, a 2 sided positive acting pre-sensitized board. I have well constructed frame to hold the pcb and film in place while exposing to light.
How would you go about getting both sides ready for etching? So far I see side 1 being exposed. After that comes ( and this is where I am asking about the process order) developing of side 1 circuit, drilling registration holes, exposing side 2, developing side 2. Last step of course is etching.
I am concerned about the handling of the board during these processes. The frame is tight, and I don't want to be scratching or scraping away any of the resist while messing around.

As an example, do I drill registration holes prior to any exposure at all, side 1 or side 2? Do I develop both sides at same time?
Or, do I do side 1 exposure, develop, drill registration, and then move to side 2? This makes me wonder, can I develop side 1 and later do side 2? Will that double dipping mess up the first developing?

Regarding the registration. How will I keep the film from sliding around and become off target while placing in the exposure frame. Can't use pins, unless I cut them short enough to hold the film to the board, but not extend pass the board. Do I glue the film to the board? Tension on the pcb/film is supplied by the frame via sliding the back panel of the frame across the back side of the pcb. This creates a shear that will move things around.