pads layout 里面layers 25 是做什么的

对啊，我也想问这个问题，有时候看到零件库里的零件有做在layers25的pad，很奇怪

有人告诉过我说是出负片的时候用到的，但我没出过负片，不知道具体怎么用。猜想大概是用来把pad和周围的copper隔开的。有谁知道的比较的清楚啊

Layer 20 is a special layer used for component nudge outlines which are 2D Line shapes. By default PADS Layout uses the silkscreen as a nudge outline, but some parts need a larger clearance for manufacturing.

Layer 25 is another special layer used in PADS Layout. By default, CAM layers do not use the pad stack thermal information for their pad shapes. Since they are negative layers, the pad as defined in pad stacks is actually the antipad shape which conflicts with other layers. Pad sizes on Layer 25 become the antipads on the negative image CAM plane.

PADS Layout does not designate layer 20 or 25. They should be labeled to identify their functionality. It is recommended that layer 20 be labeled Nudge Outlines, but there are different terms for these outlines. Some refer to them as component courtyards or component keepaways.

官方是这样定义的可是还有点不清楚<！--Element not supported - Type: 8 Name: #comment--><！--Element not supported - Type: 8 Name: #comment-->