PCB Layout.....diagonal pad exits are OK?

[treez]

Hello,

...are they?.......i can't see why not.......an old school engineer once told me diagonal pad exits make the PCB "not manufacturable, ".......meaning that the PCB will not manufacture the angle between bits of copper near the pad....but my view is..."so what?"....if it doesnt perfectly manufacture that then its fine, the pcb will still be workable.....is this right?

 

[marce]

Its common practice to exit pads at 45 degrees. What they are refering to is acid traps:
**broken link removed**
www.dnu.no/arkiv1/multek_20030925_DFM.pdf
The software I uses will flag acid traps during a DRC, so I clear them as part of the design cycle.

 

[Mattylad]

I cannot see there being a problem exiting a square/rectangular pad on the corner.

 

[treez]

thanks all...

That article was good from marce......i still dont see how acid etchant can get trapped in acute angles...no matter how acute.......i thought the PCBs were washed after coming out of the acid bath anyway?

 

[FvM]

"Acid trap" isn't a technical fact, it's a descriptive term for structures that can't be exactly etched. Similar to same net copper features with too low clearance, they don't cause functional circuit problems but affect the correct appearance of a board. They also make it difficult to control etching time by visual result.