EEVblog® Electronics Community Forum

Electronics => PCB/EDA/CAD => Altium Designer => Topic started by: Gregory on March 11, 2013, 06:19:14 am

Title: L M and N
Post by: Gregory on March 11, 2013, 06:19:14 am

Guys. When I put a smd component I can choose M, L or N footprints? What is the diference between than?

Title: Re: L M and N
Post by: electroguy on March 11, 2013, 09:35:27 am

I can't remember what each one stands for, but it refers to the size of the footprint/pads.
As an example, it's something like this for chip resistors, 0603, 0805 etc... (you can pick a footprint from each one and use CTRL+M to prove it's size).

L - about 10% smaller than N - use this if you are really tight for space.
N - NORMAL size, use this most of the time, if it suits you.
M - about 10% larger than N - use this if you want a larger than normal footprint.

Title: Re: L M and N
Post by: Psi on March 11, 2013, 10:36:04 am

Yeah, as said above, it's for different board densities (how close you want to pack the components)

Use M If you're soldering by hand, it will make things easier.

Title: Re: L M and N
Post by: AlfBaz on March 11, 2013, 02:09:13 pm

Least, Most and Nominal density I think are IPC nomenculture
For a given component they stipulate the size of the pads and talk in terms of heal, toe etc.
Essentially, least will be a very big pad and Most will be a very small pad thats why electroguy and psi are saying that Nominal is usually ok for hand soldering

Title: Re: L M and N
Post by: enz on March 11, 2013, 04:28:21 pm

Quote from: AlfBaz on March 11, 2013, 02:09:13 pm

Essentially, least will be a very big pad and Most will be a very small pad thats why electroguy and psi are saying that Nominal is usually ok for hand soldering

Sorry, but it is the other way around.
Least: means the least space occupied, --> small pad --> high density --> difficult for hand soldering
Nominal: means normal sized pad, between Least and Most
Most: means the most space occupied, --> big pad --> low density --> easy to hand solder

Martin

Title: Re: L M and N
Post by: Gregory on March 11, 2013, 05:02:39 pm

Thanks guys. So the component size and package are the same? but what changes is nly the pads? right? It's my first SMD pcb, I will use M so. I wilk make the board on OSH park, you think I wii get to use 0603 resistor? or is better I start with 0805? thanks

Title: Re: L M and N
Post by: mrflibble on March 13, 2013, 04:29:59 pm

If you have the pcb room I'd say go for 0805, that makes it a bit easier for hand assembly. Currently doing a layout as well for a 5x5 cm board. And at first I wasn't sure if everything was going to fit so I started out with 0603 parts. But turns out that there's room after all, so I changed all the 0603's to 0805's purely to make things a bit easier for myself.

Using N (nominal) pads here for the 0805's.