Hi all,
For pcb library creation, through hole parts which drill size we can use finished hole or normal hole??
Anyone can help me in this doubt…
LibrePCB and the Hole diameters
In simple, we know two types of holes in the PCB design:
- PTH - Plated holes - for multilayer PCBs - conductive, galvanically coppered holes for electrical connection between layers.
- NPTH - non-plated holes - drilled holes without electrical connection between layers (single-layer PCBs have all NPTH holes)
LibrePCB generates drilling data based on how it defined in the footprint library.
Thus, if a 0.3 mm pad’s hole is defined in the library, the generated NC drill file contains information about the 0.3 mm tools used. The diameter is not adjusted.
Probably all PCB manufacturers (I don’t know otherwise) take the diameters given in the NC Drill file as the FINISHED hole diameter. So, based on the technology used and the thickness of the
plating, it adjusts the diameter of the used drill (it knows its technology).
Theoretically, there can exists manufacturers who understand the averages given in the NC Drill as the average of the tool used, but I don’t know theirs.
Therefore, I recommend this to check on the manufacturer’s website.
So: Drill diameter in the LibrePCB’s footprint library = FINISHED hole diameter in the manufactured PCB
I use hole diameter as is appointed in the part’s datasheet.
Don’t forget: Drilling is the most expensive and time-consuming process in PCB production.
And finally, little bit theory for PCB design:
Sierra Circuits-Design Guide for DF - https://pages.protoexpress.com/rs/727-TSC-367/images/DFM%20Handbook_June%202021.pdf