so what is this green cross?..newbie question

[Martiniko]

Hi,

I am a bit new to this with making PCBs and I have a question:

What is this green cross in the middle of the image? (see attached image).
Is it necessary to have it? (I have seen it in a lot of footprints)
it´s a print screen from one of the parts that I have. (I am using Altium designer).

Another question:
What reference point (for origo in the footprint) should you use when you make your own footprints? pin number 1 in the footprint? or the center of the footprint? or it does not matter?

[ANTALIFE]

The green cross is the centre of the component, I would leave it on there as it's just more info that might be useful for the assembly house. Plus it's on it's own mech layer so is not really "hurting" anybody.

As for what centre point you should use, I think the IPC standard is the centre (of mass?) of a component. I would recommend using PCB Library Expert (http://www.pcblibraries.com/LibraryExpert/) when creating your footprint, as it generates IPC compliant footprint, so one less thing for you to worry about

[Martiniko]

Ok, thank you for the information.
I will check out that page you linked to.

Do I need to put one cross in if I would make my own footprint?
my theory is that it could be for the pick and place machine to know to what position to lift the component to. (but its just a theory of mine)

[ANTALIFE]

Your call, again I would just use the program I linked as it takes care of everything.

When someone sets up a pick & place machine they feed in a pick&place file which states the X/Y coordinates of all components, with each component usually being referenced to their origin/centre. There might be some places that also feed in the component outline Gerber mech layer