On Tue, 11 May 2004 20:28:40 -0400 Dan McMahill <[EMAIL PROTECTED]> wrote:
> On Tue, May 11, 2004 at 12:42:17PM -0700, David Koski wrote: > > Hello, > > > > In the following file: > > > > http://kosmosisland.com/island/david/test_1.pcb > > > > I have a SOT-428_Transistor (Q1) footprint that I made. With a solder mask as > > shown in the file, I cannot get the large pad closer than about 170 mils from > > the edge of the board. It is as close as it can get in the above referenced > > board. If I make the solder mask parameter small, the pad can be placed next to > > the edge of the board. What am I missing? > > I think PCB is preventing the soldermask relief from extending beyond the > edge of the board. That is what I thought. But it doesn't seem to add up. Using the following example: Pad(0 -92 0 -92 275 20 315 "" "2" 0x00000100) Thickness: 275 Clearance: 20 Mask: 315 I expect a 10 mil clearance between the pad and any polygon (Clearance parameter/2). [Land Pattern Creation for Thomas Nau's and Harry Eaton's PCB, Stephen Meier, May 2, 2003, {Example 2}] I expect a margin between the pad and solder mask to be 20 mils ((Mask parameter/2)-(Thickness parameter/2)). [Land Pattern Creation for Thomas Nau's and Harry Eaton's PCB, Stephen Meier, May 2, 2003, {Example 3}] But given a Mask parameter of 315, I cannot get closer than about 170 mils from the edge of the board. I'm still missing something. Regards, David Koski [EMAIL PROTECTED] !.nospham
