I use KiCAD with the JLC PCB Fabrication Tool plugin to generate the Gerber files at the end and send them to the factory. I’ve done this a few times before and have had no issues.
My KiCAD version 8.0.3.
This time, a JLC PCB engineer raised a question about drill compensation in the automatically generated Gerber files I sent them.
I’ll quote:
"We’d like to confirm an issue found by the engineer during the generation of the production file.
As shown below, comparing the drill diameter the drawing chart, it seems that the holes on the drill layer have been compensated, is the file used for production before? Usually,The drilling data in the original file are not integer, but now the drilling data in the file are integer, so we are confused.
Please help to confirm A or B?
A: The file is production file, we fabricate as per this gerber without further compensation and optimization
B: The file is original file, that means need compensation and optimization, we will add +0.05mm for NPTH and +0.15mm for PTH, +0.015mm trace width when we making production file."
The area of the board indicated by their arrows is the PTH holes, diameter = 0.8mm, contact pad diameter = 1.6mm. The board also contains vias with a diameter of 0.3mm.
Why do they feel like the holes on the drill layer have been compensated (meaning those +numbers are already applied to the Gerber drill files)? Also not sure what they mean is that the drill data in the original file is not an integer, but now the drill data in the file is an integer.
So what is it? Are your drill sizes in integers (whole numbers) or not? What units have you used for creating the drill file? It looks like JLC expects metric units, just like 99.5% of all the countries on this mudball.
In your screenshot I see r300 and r800 Maybe you did not use the Decimal Format during creation of the drill file.
This “compensation” they are talking about is because of the difference in drill diameter and finished hole diameter. Normally the numbers in the drill files are for the finished hole diameter, and JLC (apparently) adds 50um for their drills to accommodate for the plating thickness. (Plating thickness is typically 17um, so 34um difference in diameter).
I use the “JLC PCB Fabrication Toolkit” plugin to automatically prepare all gerber files based on their requirements and standards. It has worked fine for my last few orders. This is what makes me think that maybe there have been some recent changes in KiCAD that I/they are not aware of.
My drill sizes are not an integer numbers. They are listed in metric units with decimal places.
Anyway, I replied to them to apply all necessary compensations on the drill diameters of the plated through holes. This is beyond my control. I only need the final PTH diameters as it is in the PCB design.
Good for mentioning that, but not so good for using such an old KiCad version. I suggest you update to KiCad V8.0.9 and try again. There are probably some 400+ bug fixes between V0.0.3 and V8.0.9.
For the rest, I don’t like using plugins for fabrication output. If it works, swell, but if there is any sort of problem, then you’re pretty much stuck.
