What is the benefit of using Component Classes?

[gyuunyuu1989]

So far I have understood that net classes make it possible to group nets and then assign specific design rules for them in Altium. Then I believe I have grasped the basic idea behind "Room" which is where we can assign specific design rules to a 2D area on the PCB. Is this correct?

What I have not seen mentioned much and I do not understand is, the idea of component class. So I know that components can be classified like passives, transistors, ICs e.t.c. But what does this concept of component class really mean in Altium? Is it actually used often?

[robertferanec]

I almost never use component classes, especially the classes automatically generated based on the page they are located on (I always disable this feature).

I think I have used it once or twice when I created special component class for special components to apply some special rules, but I don't remember the exact case. Also maybe some people use it when they create reusable blocks or something like that (or they have the same circuit on multiple schematic pages and they don't want to mix components between them).

Rooms: yes, they are useful to apply special rules in special areas e.g. special clearance and track width under and around chips with very small pitch.

[gyuunyuu1989]

When was this component classes feature introduced? The concept sounds interesting that we can assign component class e.g passive component, transistor, IC e.t.c, but it is not clear what would be done once they have been classified.

Since you do not use it, it means that it does not add much value at all.

[qdrives]

I use component classes for some 'mechanical' components. These components would generate collisions in the standard rules, but they are excluded from that rule by the component class.

Fiducials, logo's etc. that do not have a 3D body are similar. However, Altium now has the ability to exclude them for that same reason. That would require all 'normal' components (footprints) to have 3D bodies (which I have given them).

[gyuunyuu1989]

Fudicial can't have 3D body because they are just a pad (or hole?) on the PCB. Does Altium have a problem if a component does not have a 3D body? I thought only the courtyard layer information and the height of the component maybe, is used to check for collision.

[qdrives]

If the fiducial is (partly) below a through hole component or it overlaps a pcb logo (think in squares) Altium will flag it.as a collision.
Courtyard is not used (by Altium).