Creating a SMD PCB footprint for construction class 4
Construction class 4 is 0.3mm copper, 0.35mm gap, 0.2mm silkscreen.
- Set grid to unit according to source drawing
- Draw the pads on the solder layer using the line tool and pins using
the via tool. Use CTRL-m to measure and precisely position.
- For pins, set annulus inner size by ("changedrillsize(...)") and
annulus outer size by ("changesize(...)")
- Draw the silkscreen with 0.2mm line thickness on silk layer. The centerline
of the silkscreen to be the outermost possible edge of the component. The
silkscreen thickness is an allowance for positioning error.
- Draw an alignment cross in the component reference point (usually the
centroid). Use two rectangles placed on "unused" or
- Check all dimensions according to drawing using CTRL-m
- Go over each pad or pin, press 'n' and enter the pin/pad number.
- ALT-a, go at the alignment cross, CTRL-x
- Buffer -> Convert buffer to element
- Screen -> Grid setting -> 100mil or 2mm
- Place the element somewhere apart from the original drawing
- Press 'q' on all pins/pads which should be square, or over the symbol
if all pads should be square.
- Go over every pin/pad, press 'n' and reenter the presented number
- Turn on soldermask by Screen -> Enable view soldermask
- Now you need to change soldermask for all pads. Always select all pads with
the same thickness (measure in muls using CTRL-r). Execute
- Turn off soldermask by Screen -> Enable view soldermask
- Turn off silk
- Select solder layer
- Draw a big rectangle over the footprint
- Press ':', enter "changeclearsize(selectedobjects, 0.35, mm)"
- Remove the big rectangle
- Turn on silk
- Press 'n' over the silk and for a resistor enter R000, capacitor C000,
coil L000, transistor Q000, soldering point T000, diode D000 etc.
- Place the label suitably near the footprint
- Press 'd' over the footprint, check the numbers, press 'd' again
- Select the whole footprint
- Go at the middle of the diamond, CTRL-x
- Save buffer elements to file, enter desired filename
- File, Quit Program, OK to lose data? OK.
- Add your created file into your revision control system and start pcb
- Load element data to buffer, enter the name of the file
- Click somewhere and check the footprint looks as expected