Purpose of different layers in PCB design

[mack369]

Can someone give me an explanation what is the purpose of different mechanical layers in PCB design software?

I've found this thread:
https://www.edaboard.com/threads/114899/
but the inner link doesn't work.

 

[bjuric]

Mechanical layers are used to provide help with manufacturing process. Board outline, cutting info, dimensions, etc.
They don't play in the layout and design of the board.

EDIT:
There might be something useful in this link: https://www.alternatezone.com/electronics/files/PCBDesignTutorialRevA.pdf

 

[mack369]

Pretty obvious, the question is what is exact meaning of each mechanical layer.
For example mechanical 1 specifies the dimensions of the board etc.

 

[bjuric]

Oh sorry for that.
The meaning and use of mechanical layers is up to company's internal policy.
'Mechanical layer' is just a generic name, You change that to a more descriptive name.

Hope this time I got it. ;-)

 

[andre_luis]

It is possible to use some of that 'strange' layers to aid in some special functions.
For instance, I added this 'strange' Layer, only in the Bottom-side component Pad, used at Test-points.
At gerber generation, could be generated a map to that coordinates.

+++

 

[mack369]

I see. So, there is no global standard for those layers.
This explains why I couldn't find anything on the web

 

[nelsonys]

Mechanical Layer, besides for mechanical outline of the board, you can use it also for different indication. Say you want to keep a clearance of 4mm in between frame ground from other pins and traces, you could just draw a 4mm wide line in between using mechanical layer as an indication to keep the clearance.

Most of the PCB design software support "cut/subtract", therefore if there's a plane fill overlapped with this mechanical line, you can simply subtract it out from the mechanical line. It ease your day for keeping clearance just simply using mechanical layers.

 

[marce]

Have a look at some IPC specs such as IPC-222x series, IPC-251x series etc there are numerous guidlines on the required information for the complete fabrication of a PCB and as such the required information you can put on the various layers.
I use mechanical layers mainly for the PCBs routing information, ie drawing the paths for the various routing operations during the fabrication assembly and de-panelisation operations.