The default via pad and hole size Protel uses is rather large, a smaller via and hole size should probably be selected.
The other major factors would be the routing rules for: - The spacing between the pins of the PGA socket. - The trace widths. - The clearance between the tracks and to the PGA pads. If you've calculated these and you really are out of routing channels, you probably do need to add more layers. With 200+ I/O pins, if even half of those pins are outputs, and they are switching all at the same time, or switching at high speeds, you will benefit from having Power and GND planes in other ways. Less noise, less ground bounce, better EMI, etc. Moving the GND/PWR to the planes (and the wider tracks probably supplying them) will make routing it easier. With a 200+pin PGA, I'd want (you may even need) the planes. ---Phil WV> Hello, WV> I am looking for some info and help on a decent routing WV> scheme for a 200+ pin PGA socket. I am using only a 2 sided board WV> right now, but wondering if a 4 layer layout would be best. WV> Customer wants to go low cost...... WV> Seems you run out of routing room from the inside pins to the WV> outside ones. Not much room to drop vias in. WV> I thought I might have to pull out the center pins to put in WV> vias, but run into the problems again, no routing room. WV> Any suggestions or visual aids? WV> Thanks from a new protel99 user! WV> Leif WV> [EMAIL PROTECTED] WV> Posted from Association web site by: Leif Erickson * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
