Context
This page was created by Daniel Puratich to standardize how custom hardware is designed with respect to mounting hole dimensions and mounting patterns during the 2023 competition cycle and is being improved over time. This document is valid for at least 2023 System Architecture & 2024 System Architecture . This document directly refers to Connector Standards as well for implementation. This standard was initially discussed as a part of 2023-02-11 - EE Hardware Mounting Hole Specification in RFC Forum as a collaboration between WARG’s electrical and mechanical subteams.
Mounting Holes Sizes
For general custom EE flight PCBAs going forward we will follow this mechanical mounting hole specification:
“Large” Boards:
M3
Used on any PCBA with area exceeding 2500 mm^2
3.40 mm hole diameter
0.10 mm hole diameter tolerance
6.00 mm annular ring diameter
“Medium” Boards:
M2
Used on any PCBA with area exceeding 750mm^2 and less than 2500mm^2
2.40 mm hole diameter
0.10 mm hole diameter tolerance
4.20 mm annular ring diameter
“Small” Boards:
No Mounting Holes
Used on any PCBA with area less than 750mm^2
No mounting holes will be present on board of this size.
Mounting will be done with double sided sticky tape or Velcro
Mounting Hole Parameters
All Mounting Holes follow the following parameters:
electrically not connected to the PCBA
This is because we want our potentially conductive drone frame to be at floating potential in accordance with General System Level Electrical Placement & Routing Guidelines
Eight vias should be placed evenly in the annular ring around the drill hole
Via’s should be plated drills in whichever drill size is used on the board
This is done for mechanical stiffness.
Proper clearance from components
Electrical component soldering pads should be at least 1mm away from the annular ring
This is done to avoid damaging the components when mechanically securing the board.
Mounting Hole Patterns
Mounting Hole pattern will be: 30.5x30.5mm
This commonly used in COTS world so we’re picking that up on WARG as well.
In the past we made a mistake and actually used 30x30mm. See convo around mounting hole mistake discussion . In theory 30x30mm will work its just rlly tight.
Mounting Hole Standard Specifications Exceptions
Exceptions can be made to this in some cases. This is meant to be the general rule. If a WARG board is violating these rules please ensure proper engineering justification is given!