Q about number of vias on a QFN-24 footprint

[hatman9]

So I used altium's footprint wizard to make the footprint given here: **broken link removed**

This is my first time making a footprint and I was wondering if the number of vias matters?

the part is: https://media.digikey.com/pdf/Data Sheets/SMSC/LAN8720.pdf
my footprint is attached

also accepting advice on anything you think I may have messed up or need to know when making footprints

 

[barry]

The only reason for those vias would be for thermal conduction; does that device have a metal pad on the bottom? If not, I don't think those vias are going to do much for you. There are some guidlines out there about thermal vias; often the manufacturer will have recommendations. You need to know the parameters of your PCB, e.g., #planes, material, ambient temp, etc.

 

[keith1200rs]

You should be following the PCB layout guidelines from the manufacturer **broken link removed**

That said, while they say "use as many vias as will practically fit ..." their examples do no such thing!

Keith.

 

[marce]

Try and get IPC-7093