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2 layers317.3 × 154.8 mmLCK75, the printed circuit board in 3D

The 2nd revision of the LCK75, this is updated to have support for ISO and split backspace layout options

Size
317.3 × 154.8 mm
Copper layers
2
Thickness
1.6 mm
Parts
208
Nets
132
Pads
779
Tracks, vias
1,094, 44
Pours
2
Routed
Yes
KiCad
KiCad 6 (file 20211014)
Created
10 Feb 2022
Updated
7 Jun 2026

Overview

LCK75 is an open-source printed circuit board by lyso1, from the lyso1/LCK75v3 repository on GitHub, published under the MIT licence. It is a 2-layer board of 317.3 × 154.8 mm with 208 parts on 132 nets, routed with 1,094 tracks and 44 vias.

It is built around the ATMEGA32A-PU. Its parts include 95 switches, 88 diodes, 7 resistors, 5 capacitors and 1 IC. It belongs with the AVR (ATmega, ATtiny) boards of this library.

Main components

1

README

LCK75 kicad libs/README.md

MX_Alps_Hybrid

KiCad Libraries of keyboard switch footprints

Footprint Image

Included Libraries

  • MX_Alps_Hybrid.pretty - The original MX/Alps hybrid support footprints.
    • FLIPPED - Reversed LED pads for overlapping switch footprints.
    • NoLED - No LED pads.
    • ReversedStabilizers - Stabilizer mirrored vertically (i.e. for bottom row).
  • MX_Only.pretty - Only for Cherry MX and derivative clones.
    • FLIPPED - Reversed LED pads for overlapping switch footprints.
    • NoLED - No LED pads.
    • ReversedStabilizers - Stabilizer mirrored vertically (i.e. for bottom row).
    • Hotswap - Kailh hotswap sockets.
  • ALPS_Only.pretty - Only for alps SKCM/SKCL, SKBM/SKBL, and clones with same pin structure.
    • LED - Specifically for Alps SKCL with in-switch indicators.
  • Kailh_Choc.pretty - Only for Kailh Choc switches.

Features

  • Designed from scratch using official datasheets and accurate measurements
  • Various footprints for all occasions
  • Almost every switch size in existence
  • Topside soldermask to prevent solder overflow and improve appearance

Upgrading

The library was overhauled on June 1st, 2019 due to its aging structure and contents.

  • The schematic components were updated to work on the 50mil grid. You can replace the components; however, it will take a decent amount of work.
    • If you wish to do this, remove the old schematic library, re-add the new one, and replace the schematic components.
  • The footprint library was divided into four distinct libraries. Remove the previous, re-add the libraries with the footprints you are using, then rebind the footprints in the schematic.

Request More Footprints

I'll be more than happy to make more custom footprints to fit your needs, time permitting. Simply contact me via Discord @ai03#2725, or twitter @ai03_2725.

Contributing

Feel free to create pull requests with more footprints. I only ask that they are of high quality, and that they are based on official dimensions, if possible.

Schematic Image Top render Image
Bottom render Image

Parts

208
QtyValueFootprintReferences
851N4148cftkb:D_DO-35_SOD27_P5.08mm_HorizontalD1, D2, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22, D23 +69
74SW_SPSTMX_Only:MXOnly-1U-NoLEDSW1, SW2, SW10, SW11, SW12, SW13, SW14, SW15, SW16, SW17, SW18, SW19, SW20, SW21, SW22, SW23 +58
6SW_SPSTMX_Only:MXOnly-1.5U-NoLEDSW31, SW44, SW82, SW83, SW88, SW89
4SW_SPSTMX_Only:MXOnly-1.25U-NoLEDSW62, SW78, SW79, SW80
20.1ucftkb:C_Disc_D4.3mm_W1.9mm_P5.00mmC4, C5
222pcftkb:C_Disc_D3.0mm_W1.6mm_P2.50mmC1, C2
23.6Vcftkb:D_DO-35_SOD27_P5.08mm_HorizontalD83, D84
25.1kcftkb:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_HorizontalR2, R5
275Rcftkb:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_HorizontalR3, R4
2SW_PUSH-keyboard_partscftkb:SW_PUSH_6mmSW87, SW91
2SW_SPSTMX_Only:MXOnly-2.25U-NoLEDSW60, SW63
2SW_SPSTMX_Only:MXOnly-1.75U-NoLEDSW47, SW75
11.5Kcftkb:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_HorizontalR7
11.5kcftkb:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_HorizontalR1
110kcftkb:R_Axial_DIN0204_L3.6mm_D1.6mm_P7.62mm_HorizontalR6
14.7ucftkb:CP_Radial_D4.0mm_P1.50mmC3
1500mAcftkb:polyfuse_5.1mmF1
1ATmega32A-PUcftkb:DIP-40_W15.24mmU1
1AVR-ISP-6cftkb:AVR_ICSP_3x2J1
1Crystalcftkb:Crystal_HC49-4H_VerticalY1
1LOGOsilky:2-lckG***
1OLEDcftkb:ssd1306 128x32 oledSSD1306
1POWERcftkb:LED_D3.0mmLED1
1Rotary_Encoder_Switchcftkb:RotaryEncoder_Alps_EC11E-Switch_Vertical_H20mm-newSW93
1SW_SPSTMX_Only:MXOnly-7U-ReversedStabilizers-NoLEDSW81
1SW_SPSTMX_Only:MXOnly-6.25U-ReversedStabilizers-NoLEDSW90
1SW_SPSTMX_Only:MXOnly-2U-NoLEDSW29
1SW_SPSTMX_Only:MXOnly-ISO-ROTATED-ReversedStabilizers-NoLEDSW92
1Type-C_USB_C_GCT_USB4085Connector_USB:USB_C_Receptacle_GCT_USB4085USB1

The 202 most common of 208 parts.

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Questions

How big is the LCK75 PCB?

It measures 317.3 × 154.8 mm and has 2 copper layers, 1.6 mm thick.

What parts does the LCK75 use?

208 parts, built around the ATMEGA32A-PU. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the LCK75 KiCad files?

From the lyso1/LCK75v3 repository on GitHub, at the commit this page was made from: the board is LCK75 kicad libs/LCK75.kicad_pcb and its schematic LCK75 kicad libs/LCK75.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the LCK75 design in my own project?

Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).