Difference between revisions of "Cutting the Board"

From APL
Jump to: navigation, search
(Created page with "Measure the dimensions of the printed transparency, and mark these off on the physical undeveloped PCB. With a heavy duty cardstock cutter line up the PCB such that the usabl...")
 
Line 1: Line 1:
Measure the dimensions of the printed transparency, and mark these off on the physical undeveloped PCB. With a heavy duty cardstock cutter line up the PCB such that the usable portion hangs to the left of the blade. This will minimize splintering of the board when it is being cut.  When ready to cut, slice the board with force in one continuous motion.  With a cut PCB, slightly larger than the transparency, you are now ready to develop the board.
+
Our blank boards are 4x6 or 6x6 inches; There may be smaller pieces that can be used as well. If you need to cut a board, use the hacksaw. NEVER use the paper shear - It will not only cut uncleanly (destroying a half cm wide region on both sides of the blade), more importantly it will permanently warp the board and make it nearly impossible to get a uniform close contact between the artwork film and the board.
 +
 
 +
This will make the boundary between 'exposed' and 'not exposed' fuzzy and destroy the resolution of the transferred image.
 +
 
 +
Mark the white protective tape using a pen and straight-edge, then clamp the board in the yellow rubbery gentle-jaws in the vise and saw horizontally.
 +
 
 +
Once the board is cut to size, the artwork is ready in the UV chamber (READ AHEAD!), and all that remains is to slip the copper board between the films, peel the protective layer off. If the board was cut, the edges will have sharp copper sticking off them. Not only will this prevent the film from lying conformally flat against the board, it will also scratch the emulsion with devastating efficiency: If the board has been cut, after peeling the white protective film off, both sides of every cut and all four corners (even of a single-side board) MUST be turned down with a file.
 +
 
 +
This should be done with the local fluorescent lights off and the incandescents on, to minimize unnecessary exposure of the photoresist to stray UV. The deburring is complete when a fingernail (which is placed DELICATELY - you can very easily scratch the green photoresist off) glides off the edge of the board with no resistance or 'catch' at the edge.

Revision as of 13:20, 6 February 2019

Our blank boards are 4x6 or 6x6 inches; There may be smaller pieces that can be used as well. If you need to cut a board, use the hacksaw. NEVER use the paper shear - It will not only cut uncleanly (destroying a half cm wide region on both sides of the blade), more importantly it will permanently warp the board and make it nearly impossible to get a uniform close contact between the artwork film and the board.

This will make the boundary between 'exposed' and 'not exposed' fuzzy and destroy the resolution of the transferred image.

Mark the white protective tape using a pen and straight-edge, then clamp the board in the yellow rubbery gentle-jaws in the vise and saw horizontally.

Once the board is cut to size, the artwork is ready in the UV chamber (READ AHEAD!), and all that remains is to slip the copper board between the films, peel the protective layer off. If the board was cut, the edges will have sharp copper sticking off them. Not only will this prevent the film from lying conformally flat against the board, it will also scratch the emulsion with devastating efficiency: If the board has been cut, after peeling the white protective film off, both sides of every cut and all four corners (even of a single-side board) MUST be turned down with a file.

This should be done with the local fluorescent lights off and the incandescents on, to minimize unnecessary exposure of the photoresist to stray UV. The deburring is complete when a fingernail (which is placed DELICATELY - you can very easily scratch the green photoresist off) glides off the edge of the board with no resistance or 'catch' at the edge.