Imported from GitHub: FradSer/EC75Mac · commit 9e177d5 · license MIT

Description

Open source universal 75% Electrostatic Capacitive PCB (macOS first).

README

EC75Mac

Open source universal 75% Electrostatic Capacitive PCB (macOS first).

Introduction

This project is a continuation of my development of open source EC boards.

The supported layout options are the following:

Mapping is purely for demonstration purposes, remapping of all keys is supported.

Technical information

• Layout size: 75%
• Compatible switches: EC switches (Topre and NIZ)
• Microcontroller: STM32F401
• Connector:
  • USB-C
  • JST connector for daughterboard
• Firmware compatibility: QMK (with VIA/VIAL support)
• Protection hardware (on all connection methods):
  • Fused
  • ESD protection

Renders and Prototypes

Render

Mainboard:

JIS Plate:

HHKB 6U Plate:

HHKB 7U Plate:

Prototype

NOTE: the prototype PCB doesn't include a USB port and the JST connector is in a different position compared to the one in the render. This is because the above was a modified version of the PCB to be used in Vero. For all intents and purposes, the PCB is the same.

Revisions and relative features

Rev1

This revision implements all the main features of the PCB.

Connectivity

Both onboard USB-C and JST connectors are supported. In both cases the protection features are preserved (fused and ESD).

PCB order procedure

In order to have me highers compatibility possible with PCB manufacturers, I decided to design the board around the JLC7628 Stackup from JLCPCB.

The rational behind this is that the JCPCB stackup is relatively cheap and if the board worked with the stackup, it would be easier to get the board to work with pretty much any other many that offer an equivalent stackup and higher prices.

The plates can be instead be made out of standard 2 layer stackup or with metal, like the Realforce plates.

Production files

The production can be found in the Production folder.

In there you'll find the main PCB files and the JIS and HHKB plates.

As usual the *.zip files are the gerber files, BOM-*.csv are the BOM (Bill Of Material) files and POS-*.csv are the POS/CPL (Footprint POSition/Component Placement List) files.

Mainboard

As mentioned above, the mainboard is designed around the JLCPCB stackup. The mainboard is a 4 layer board.

Here are the options to select when ordering the mainboard:

• PCB thickness: 1.6mm or 1.2mm
• Impedance: NO
• Layer stackup:
  • L1(Top layer): EC60-F_Cu.gbr
  • L2(Inner layer1): EC60-In1_Cu.gbr
  • L3(Inner layer2): EC60-In2_Cu.gbr
  • L4(Bottom layer): EC60-B_Cu.gbr
• PCB Color: whatever you like
• Surface Finish: whatever you like
• Material Type: FR-4 TG155

All the other options can be left as default.

Assembly options

Here follows the options to be used for assembly:

• Assembly Side: Bottom
• Tooling holes: Added by JLCPCB
• Confirm Parts Placement: yes

NOTES ABOUT THE OPTIONS

• Once you upload the gerber files wait for the system to automatically recognize the board outline and layers. It will take a while, be patient.

• PCB thickness has been tested on both 1.6mm and 1.2mm so it's your call on which one to use.

• For Material Type I strongly suggest to use FR-4 TG155, using the standard FR4-Standard TG130-140 material might result in the board delamination and generally is not advised on 4 layer boards.

Plates

The plates are designed to be 2 layer boards. All the default options can be left as default, the only thing to change is the PCB thickness option, which should be set to 1.2mm.

Copyright notice

This project is released under the MIT License. For the license, please refer to the LICENSE.md file.