EEVblog Electronics Community Forum

Electronics => PCB/EDA/CAD => KiCad => Topic started by: Kalcifer on June 04, 2021, 05:16:04 am

Title: What is the difference between these 4 types of mounting holes?
Post by: Kalcifer on June 04, 2021, 05:16:04 am
[attachimg=1]
MountingHole_2.2mm_M2_ISO7380_Pad_TopOnly <-- I think this one only has a copper pad on the top
MountingHole_2.2mm_M2_ISO7380_Pad_TopBottom <-- I'm not sure what the difference is between this one and the next
MountingHole_2.2mm_M2_ISO7380_Pad <--
MountingHole_2.2mm_M2_ISO7380 <-- I think this one is just the hole with no copper pad
Title: Re: What is the difference between these 4 types of mounting holes?
Post by: ebastler on June 04, 2021, 05:34:35 am
I think the difference between the second and third variant only matters for multilayer boards. The regular "pad" (the third one) also has pads on all inner copper layers, while the "pad_topbottom" has them only on the outer layers. So when you use a pad with a connection in your schematic, e.g. for grounding, a plated through-hole can connect either just the outer layers or the internal layers too.

You can study the footprints in KiCad's footprint editor to see how they are set up in detail.
Title: Re: What is the difference between these 4 types of mounting holes?
Post by: Doctorandus_P on June 07, 2021, 05:01:34 pm
The easiest way to compare differences is to just put them all on a PCB and then look at them in KiCad's 3D viewer.

[Edit]
In this particular case however, there is not much to see in the 3D Viewer. All 4 variants have are a Non Plated Hole, and the main difference seems to be the size of the graphical cirles around it.
[attachimg=1]
Title: Re: What is the difference between these 4 types of mounting holes?
Post by: ebastler on June 07, 2021, 06:13:19 pm
I'd assume they become plated through-holes if you use them with a symbol which has a connection to the pad(s)?
Title: Re: What is the difference between these 4 types of mounting holes?
Post by: Doctorandus_P on June 07, 2021, 09:43:04 pm
Oops, I goofed up a bit with my previous post.
Screenshot is of mounting holes without pads.

If you do the same with mounting holes with pads however, you can see and compare where these footprints differ.

@ebastler:
Almost.
I assigned the footprints of my first screenshot from schematic symbols without pads for the mountingholes, and the (configurable) filter in cvPCB filtered out the pads with copper.

A good way to search through footprints is with the footprint browser. It has a "regular expression like" search function, and when seeking for "hole" and "2.2" (just a space between the two) Then you see 17 footprints for a 2.2mm hole:

[attachimg=1]