This has been discussed previously. The Yahoo Groups search tool is pretty hopeless so I used Google to search for the relevant thread for you, which it found first in mail-archive starting at:
http://www.mail-archive.com/kicad-users@yahoogroups.com/msg06539.html Does that help? Regards, Robert. On 24/08/2010 13:33, James Moody wrote: > A number of components I've come across lately (DC motor controller chips, > ESD protection devices, for example) have a thermal or ground pad underneath > the chip. This requires that a large pad be included in the footprint, and > the usual recommendation is that several vias are used in this pad to > connect it to the ground layer. This is also part of the thermal management > scheme. > > For example, if you look at page 10 of the datasheet for the Allegro A4983, > it describes how to lay out the board. It shows 9 vias in the under-chip pad > used to aid in solder flow and heat transfer. > > My first thought for how to do this in KiCad was to define a bunch of vias > on the board. My second thought was to change the module so that the large > pad was actually several small pads butt up against each other, tiled > together to make one large pad, and have each pad be a through-hole style > pad with a very narrow drill. > > Is there a better approach or feature I've missed? > Thanks. > --Jim > > > > > > No virus found in this incoming message. > Checked by AVG - www.avg.com > Version: 9.0.851 / Virus Database: 271.1.1/3090 - Release Date: 08/23/10 > 19:34:00 >
No virus found in this outgoing message. Checked by AVG - www.avg.com Version: 9.0.851 / Virus Database: 271.1.1/3091 - Release Date: 08/24/10 07:34:00
