So this is where the magic will hopefully happen, I finally make a high density double sided PCB. Will I succeed? Will I fail? Watch the video to find out!
This is the seventh episode in a series where I am challenging myself to make the best possible DIY PCB’s using commonly available low cost CNC technologies.
Below is some detailed documentation about my method.
[SOFTWARE USED]
- KiKad Version 6.0.6 (Circuit & PCB Design)
- FlatCAM Version 8.994 BETA (Generates G-Code, but requires editing)
- Grblcontrol (Candle) Version 1.17 (CNC Control)
[CNC SETUP]
RATTMMOTOR CNC 3018 Pro (with modifications as follows)
- Aluminum 3018 Z-Axis Module + X-Axis upgrade kit
- StepperOnline NEM17 42Ncm Stepper Motors (x3)
- LaserTree Gold 450nm 40W-Pro 12V 20mm Fixed Focus Laser
- Custom end stop switches (x6)
- Custom emergency stop button
- Custom Z & X-Y probe
- Custom cable management
- Custom waste board & PCB Mount + Locating Pins
- 0.7mm & 3mm End mills (Range of sizes on hand is recommended)
- Using ThinkPad E495 to control the CNC
[OTHER EQUIPMENT]
- Elegoo Mercury UV Exposer
- Mini-Bandsaw
- 150 Mesh Silkscreen
- 150mm Embroidery Ring
- 10cm Rubber Spatula
- Fine haired toothbrush
- Ikea glass & plastic containers
- Hand File
[CONSUMABLE ITEMS]
- Ferric chloride etchant solution
- 70mm x 100mm Double Sided Copper Clad FR4 PCB
- Ferric chloride etchant solution
- Mechanic UVH900-WY 10ml UV Resin (White) Fast 10sec curing
- WNB UV-W100 100g UV Resin (Green)
- Conduction CD-LT528 138 degree lead-free solder paste
- Hozan H-42-3717 0.8mm flux core leaded solder
- 0.7mm wire (for vias)
- Isopropyl Alcohol (99.8% or greater)
- Tissue Paper
*********** KiCad Track & Clearance Information ***********
- Grid = 0.3175
- Clearance is factor of 0.5 with minimum of 0.15 (0.1mm laser 50% overlap)
- Track width minus clearance should be factor of Grid (examples follow)
0.3175 - 0.15 = 0.1675
0.6350 - 0.20 = 0.4350
0.6350 - 0.25 = 0.3850
0.6350 - 0.30 = 0.3350
- Fill clearance 0.2mm and min width 0.25. Must be 0.635 from board edge
- Board cutout line 0.1mm thick with 0.635 radius corners
- Push 45 degree tracks so they are snug to each other
- Standalone pads should have a 0.4mm stubby track to sink heat during clearing
*********** FLATCAM FILE PREP ***********
[Double Sided Tool]
- Set Axis Y 2-places
- Mirror operation set W/2,0
- Mirror back layers
- Drill hole 3.6mm
- Set grid 0.5
- Locate 2 holes -2.5,-2.5 from left corners (shift-click to copy value-then +Add)
- Create excellon object
** Mill & laser origin alignment still an issue. I am working on this...
[Copper]
- Isolation Routing
- 0.1mm tool, 18 passes, 50% overlap
- Generate geometry
- Z-travel 0, X-Y feed 500, Z-feed 1000, spindle 4000 (So far this looks good. Possible cooler is even ok, but risky)
- Generate CNC job
- Save CNC Job
- Use Text editor to replace unwanted Z-moves & other
[Silkscreen]
- Isolation routing
- 0.001mm tool, 1 passes, 0% overlap
- Generate geometry
- Paint Tool
- 0.1mm tool, Overlap 50%, Offset 0, Method Standard, Disable connect
- Generate geometry
- Z-travel 0, X-Y feed 500, Z-feed 1000, spindle 2500 (So far this looks good. Possible cooler is even ok)
- Generate CNC job
- Save CNC Job
- Use Text editor to replace unwanted Z-moves & other
- Save modified version with spindle 150 (For setting UV resin) add "_UV_Expose" to filename
(150 works well with fast resin "Mechanic" white, clean with alchohol & final UV expose for 30 secs)
[Mask/Clear Pads]
NOTE: This setting is usable but must be improved.
- Isolation routing
- 0.001mm tool, 1 passes, 0% overlap
- Generate geometry
- Paint Tool
- 0.1mm tool, Overlap 0%, Offset 0, Method (Lines), Disable connect
- Generate geometry
- Z-travel 0, X-Y feed 800, Z-feed 1000, spindle 2500 (Leaves some residue for cold pads, but any hotter is no good)
- Generate CNC job
- Save CNC Job
- Use Text editor to replace unwanted Z-moves & other
[Board Cutout] (Board Cutout line is 0.1mm, round corners)
- Cutout Tool
- Tool 0.1, Cut-Z -0.858, MultiDepth 0.058, Margin 0, Gaps (None)
- Generate Geometry (X)
- Select geometry
- Z-travel 2, X-Y feed 500, Z-feed 1000, spindle 10000
- Generate CNC job
- Save CNC Job
- Make sure cut line well with etched copper zone!
[Alignment Drills]
- Drilling Tool
- CutZ -7, TravelZ 7, FeedZ 50, Spindle 10000
- EndMoveZ 25, PreProcessor (GRBL_11_no_M6)
- Generate CNC Job Object
- Save CNC Job
[Pad Holes]
- Drilling Tool
- CutZ -2.5, TravelZ 1.5, Spindle 10000, Dwell 1
- ToolChange 25, EndMove Z 25, PreProcessor (GRBL_11_no_M6)
- Generate CNC Job Object
- Save CNC Job