Component footprint terms

[edward101]

I was talking with a friend of mine the other day about component footprint verses component body size. He said the footprint is the body size, it this true? I always saw them as being different.

 

[MacGyverS2000]

I'm not sure I understand the question...

From a mechanical standpoint, the footprint is indeed the body size... the component takes up whatever space it takes up, plain and simple. That is, by definition, the footprint of an object.

From a PCB pad layout standpoint, it depends on your method of soldering (wave, IR reflow, hand, etc.). In the case of wave soldering, it also depends upon the component orientation compared to the flow direction of the wave.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[melone]

I've always understood it as follows. The footprint implies the pads on the PCB, i.e. where the actual traces connect (where the leadframe connects to the PCB). The component body is the encapsulated die(s), sustrate + leadframe, i.e. the black IC. The component body can be larger than the footprint (BGA) or smaller (TSOP, etc.).

Hope that helps!

 

[edward101]

melone,
That is my understanding also. I guess it depends. If it is the CCA, it is the component body. If you are looking at the PWB, it is the actual connections.

 

[IRstuff]

From a generic perspective, a body size is the physical extent of the object. The footprint, is the space claim of the object, which is at least the body size, and includes the overhead and infrastructure to support the installation and use of that object.



TTFN

FAQ731-376

 

[GonzaloEE]

As IR stuff said, footprint isn't the same as 'assigned PCB area'. Stripline antennas and some transformers require a certain clearance from other PCB parts, thus more PCB area than their physical shape. On the contrary, some UHF transceivers are quite big, though you can always drop some SMD parts below.

IMO a good footprint file will include both pad pattern and physical outline.