Footprint drawing - maximum size of a hole

Thread Starter

duykwe

Joined Nov 17, 2023
71
I am drawing a footprint of a 4PDT, the holes are 0.8 x 2.0mm. When I draw the footprint, should I draw the same dimension as the layout (I am scared that the real component might not fit the board), or make it a bit bigger, if so, can you suggest the value I should use? Thank you guys so much.
1702195477094.png
 

ericgibbs

Joined Jan 29, 2010
18,845
hi duy,
I thought you meant the mounting holes for the switch body.

Do you have an actual switch on the bench to check the fit for the terminals?

E
 

Thread Starter

duykwe

Joined Nov 17, 2023
71
hi duy,
I thought you meant the mounting holes for the switch body.

Do you have an actual switch on the bench to check the fit for the terminals?

E
yes, I have it. Do you mean I should measure the size of the lug solder to make sure it fits the layout? Please tell me if I misunderstood something. Thank you so much!!
 

MrChips

Joined Oct 2, 2009
30,795
Check with the PCB manufacturer if the specified hole size is the drill size or the finished hole. The finished hole will be narrower than the drill size.
 

Thread Starter

duykwe

Joined Nov 17, 2023
71
Check with the PCB manufacturer if the specified hole size is the drill size or the finished hole. The finished hole will be narrower than the drill size.
And if it's finished holes, then I will add like 5 - 10 % as ericgibbs says above, but for the drill ones, just keep it, right? Thank you so much!
 

MrChips

Joined Oct 2, 2009
30,795
And if it's finished holes, then I will add like 5 - 10 % as ericgibbs says above, but for the drill ones, just keep it, right? Thank you so much!
No. You have that wrong.
If the drill size is specified, the finished hole diameter will be reduced by about 4mil (0.004" or 0.1mm).
You still want to increase the hole size by about 5-10% plus 4mil. For larger components such as connectors and switches I would prefer to have a larger hole than a hole that is too small.
 

Thread Starter

duykwe

Joined Nov 17, 2023
71
I got it now, thank you so much!
No. You have that wrong.
If the drill size is specified, the finished hole diameter will be reduced by about 4mil (0.004" or 0.1mm).
You still want to increase the hole size by about 5-10% plus 4mil. For larger components such as connectors and switches I would prefer to have a larger hole than a hole that is too small.
 

MrChips

Joined Oct 2, 2009
30,795
Also, don't go by the 2.00 mm alone. The corner-to-corner measurement will be greater.
In this case, I think a 2.20 mm finished hole will be fine.
 

eetech00

Joined Jun 8, 2013
3,942
I am drawing a footprint of a 4PDT, the holes are 0.8 x 2.0mm. When I draw the footprint, should I draw the same dimension as the layout (I am scared that the real component might not fit the board), or make it a bit bigger, if so, can you suggest the value I should use? Thank you guys so much.
View attachment 309687
The pins can vary in size.
Somewhere on the diagram it should state what the tolerance's are. That will provide guidance on the size of the hole.
 
Top