This is a discussion I have had with our designers when we should be using thermal reliefs for connections to ground planes.  For low current it is a "don't care" but when we get into high current (>10A) the spokes should get larger and will essentially become no thermal relief.  We use PADS PowerPCB and I believe it can handle the changes.  Just getting folks to do it. (it is extra work... sigh)

But this is just my opinion,

Phil

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of grandrien
Sent: Monday, November 25, 2013 3:28 PM
To: [log in to unmask]
Subject: Re: [TN] PWB/PCB, clearance ring

Hi,

We use same clearance from pad outline whatever the hole diameter in middle. I don't see the reason for different values. Main reason for the copper clearance is the copper etching precision for pcb mfg, electrical isulation for PCBA reliability or assembly.

Rgds


========================================
Message du 25/11/13 15:39
De : "Victor Hernandez" 
A : [log in to unmask]
Copie à : 
Objet : [TN] PWB/PCB, clearance ring

Fellow TechNetters:

Are all PWB/PCB internal clearance rings the same diameter or do the clearance ring diameter vary by drill hole size? How is the clearance ring diameter selected?

Victor,


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