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--- pcbetching [2022-02-01 17:17] – jtdburton
+++ pcbetching [2022-07-22 22:12] (current) – [Flux] MirZa
@@ Line 22: / Line 22: @@
 There are a few approaches to this process. These instructions will assume you're using KiCad and FlatCam (both open source) for PCB design and file manipulation.
-Make sure to design your board with nice thick traces - start with at least 0.8mm and then try going smaller once you've got the hang of the masking and etching process. Try to fit everything onto a single-sided board if possible, as this means you can use the laser cutter for machining which is currently much simpler than the CNC (see notes under "Cutting" below).
+Make sure to design your board with nice thick traces - start with at least 0.8mm and then try going smaller once you've got the hang of the masking and etching process. If you can fit everything onto a single-sided board, you might be able to use the laser cutter for cutting and drilling; if not, you'll need to use the CNC (both options are detailed below).
 The first thing to create is your trace file. In KiCad, go to File - Plot. Set "Plot format" to "SVG". Select your copper layers ("F.Cu", "B.Cu", or both). Tick "Plot Edge.Cuts on all layers" (this is to help you align the mask to your cut board), make sure "Drill marks" is set to "None", and click Plot.
 Open your plot file in your vector editing programme of choice and invert the colours (assuming you're using negative photoresist film - see notes under "Exposure" below). In Illustrator, the easiest way to do this is to create a white filled rectangle slightly larger than your board, put it behind your traces, and then select all and click "Edit" - "Edit Colours" - "Invert Colours".
+===== Cutting (CNC)  =====
+The CNC is a bit tougher to get going on than the laser, but it opens up a lot more options, most notably two-sided boards.
+Start by going back to KiCad's Plot dialogue. Make sure "Edge.Cuts" is the only layer selected. Select the Gerber plot format and click Plot.
+Now click "Generate Drill Files...". Select "Excellon" as your file format here, and tick "PTH and NPTH in single file". Make sure the "Absolute" and "Millimetres" options are selected and click "Generate Drill File".
+Open up FlatCam and use File - Open Gerber to load your edge cuts and File - Open Excellon to load your drill plot.
+//Tip: at each stage of the FlatCam process below you can save your settings for next time by going to Options - Transfer options - Object to Application.//
+It's a good idea to go into the "Options" tab at the left here and make sure "mm" is selected as FlatCam defaults to inches.
+Double-click the drill plot in the layer list. You can skip over all the CNC settings here, just enter your tool size under "Mill Holes" (a 0.8mm bit is usually good) and click "Generate Geometry".
+Now go back to the "Project" tab and double-click the edge cuts layer. Enter the same tool size under "Board cutout" and set your Gap size to something reasonable. This setting creates either two or four gaps in the edge cut so your board doesn't come completely free of the stock. Four 3mm gaps is a good starting point.
+Back in the "Project" tab again, you'll have new .drl_mill and .gbr_cutout layers. Select both of these and go to Edit - Join Geometry. You'll see a new "Combo" layer. Double-click this and enter your CNC settings. Typical values will be around -1.6mm cut Z (this is the thickness of your board), 2mm travel Z, 200mm/min feed rate, and 10,000 RPM spindle speed. Click "Generate".
+Double-click the new "Combo_cnc" layer and enter "M30" in the "Append to G-Code" box (this is an "end of program" signal, and LinuxCNC won't process a file without it). Click "Export G-Code". Grab the SD card from the CNC laptop and save your gcode file on there with the file extension .ngc.
+From here, pop the SD card in the CNC laptop, load it into LinuxCNC, and proceed with the usual CNC process.
 ===== Cutting (Laser Cutter) =====
-The simplest way to cut your board is with one of the laser cutters. This is subject to two major restrictions: use FR1 or FR2 boards ONLY (FR4 vapourises into some VERY nasty stuff), and use only single-sided boards (you can't laser through copper). Instructions for cutting a board with the CNC router will be added here eventually, but the file prep steps are similar so you may be able to figure it out for yourself.
+Another way to cut your board, which you may find simpler, is with one of the laser cutters. This is subject to two major restrictions: use FR1 or FR2 boards ONLY (FR4 vapourises into some VERY nasty stuff), and use only single-sided boards (you can't laser through copper). Instructions for cutting a board with the CNC router will be added here eventually, but the file prep steps are similar so you may be able to figure it out for yourself.
 Start by going back to KiCad's Plot dialogue. Make sure "Edge.Cuts" is the only layer selected. Select the Gerber plot format and click Plot.
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 You should be able to improt this SVG directly into LaserCut 5.3, but it may take some cleanup in Inkscape/Illustrator first.
-Place your workpiece in the laser cutter copper side DOWN. Cut settings may need some experimenting to get right. The aim is to cut all the way through the substrate without hitting the copper hard enough to cause lots of sparks. My best results have come from using the big laser with speed 25, power 60, corner power 50 on 1.5mm board.
+Place your workpiece in the laser cutter copper side DOWN. Cut settings may need some experimenting to get right. The aim is to cut all the way through the substrate without hitting the copper hard enough to cause lots of sparks. My best results have come from using the big laser with speed 25, power 60, corner power 50 on 1.5mm board. However, some boards are much tougher than others so your mileage can and will vary - try cutting out a small circle as a test for new stock.
-Run the cuts. Give it a couple of minutes before you open the lid, vapourised FR1/2 isn't as bad as FR4 but it's still unpleasant.
+If you're sure you've got usable laser settings, download and run your cuts. Give it a couple of minutes before you open the lid, vapourised FR1/2 isn't as bad as FR4 but it's still unpleasant.
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-Take the workpiece out and pop your board out of it. What you're doing here is snapping the copper layer along the lines you've cut in the substrate, it'll be tough but doable. You may need to flex the board a bit. You can leave the through-holes for now, although you may find it useful to drill out a couple to help you align the trace design in the exposure step.
+Take the workpiece out and pop your board out of it. You'll need to snap the copper layer along the lines you've cut in the substrate, which should be tough but doable. You may need to flex the board a bit, or even use scissors or a guillotine on the edge lines. You can leave the through-holes for now, although you may find it useful to drill out a couple to help you align the trace design in the exposure step.
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 Where a trace has been broken, apply a solder bridge to reconnect it.
-===== Flux =====
+===== Protective coating =====
-Give your new board a spray with the can of flux. This will both prevent the copper traces from oxidising and make soldering to the board easier. Applies just like spraypaint - use back-and-forth motions from 20-30cm away.
+Bare copper traces oxidise very quickly without any protection.
+Give your new board a spray with the can of clear varnish after soldering and leave to dry for a couple of hours.
+Mask off any buttons or mechanical components with masking tape so they do not get stuck.
+Another option is to use tinning solution before soldering.
-Leave to dry for a couple of hours. Congratulations, you made a PCB!!
+Congratulations, you made a PCB!!