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--- project:beta-layout:pcbprinter:double-sided_printing [2012-11-01 08:57] – AIHgfJrYIaTBWhFUR 188.143.232.12
+++ friedhof:beta-layout:pcbprinter:double-sided_printing [2020-07-20 10:10] (aktuell) – ↷ Seite von project:beta-layout:pcbprinter:double-sided_printing nach friedhof:beta-layout:pcbprinter:double-sided_printing verschoben neos
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-If you want to get read, this is how you solhud write.
+====== pcb-printer: Double-sided printing ======
+{{tag>project hardware pcb electronics process infrastructure}}
+  * Challenge: Get top and bottom layer to align
+  * Improved process draft:
+    - Prepare layout:
+      * Eventually panelize small PCBs for better yield, check [[http://www.neufeld.newton.ks.us/electronics/?page_id=81]]
+      * Put four markers arranged in a rectangle outside of actual PCB area
+        * Markers are a 1mm diameter circular dot with a small hole surrounded by a thin 3mm diameter circle on both top and bottom layer
+      * Here's an example: {{http://dojoe.net/shack/markerexample.png}}
+    - Before printing, make sure that *no* layer has features reaching beyond the markers
+      * Otherwise, the markers will shift slightly when mirroring the layout during printing
+      * The tNames/bNames or tValue/bValue text is a likely candidate for this
+      * Fix: Smash the offending parts, delete the text
+    - Tape a piece of paper to the bottom of the tray, print the top layer to it
+      * We need the markers for later
+    - Cut the PCB into size
+      * Saves etching solution and time
+      * It might be a good idea to file away the burrs (DE: Grat), they'll wreck cloth and paper during cleaning and priming
+    - Clean and prime the PCB, put it into the tray so that it covers the print on paper, print the top layer, cure ink as usual
+    - Drill two 1.5-2mm holes through the exact center of two of the markers
+      * Copper is hard to drill, don't use your precious PCB drills for this
+      * Try to make this drill as precise as possible, your layer alignment will depend on it
+      * What worked for me: Prime the drill with a _precise_ punch mark (I used a large screw and a hammer), position the drill without power, then start drilling
+    - Remove the copper burr (DE: Grat) on the other side!
+      * Don't forget this, or the print head will scratch across the burr and smear ink!
+      * I used a larger drill that I simply turned by hand
+    - Clean & prime the still-empty PCB side
+    - Put the PCB on the tray and align it so that the marker dots are in the exact center of the holes you drilled
+      * Hence the circular shapes -- the human eye can see deviations from a circular shape pretty well
+      * If your holes came out slightly misplaced, use the two most precise holes for this and take into account their misalignment
+    - Fix the PCB in place
+      * The primer will prevent some tapes from sticking properly, maybe double sided tape to the rescue
+      * Or just tape the PCB in place before priming and prime later
+    - Print the bottom layer (mirrored!) and cross your fingers
+      * The outer circles of the markers can be compared against the drill holes to verify alignment
+    - If alignment is "good enough", cure ink and etch