How to distribute footprints


#1

Half year ago I have done one simple PCB using 4.0.7. Then have a long break. Now I have installed 5.0 and am trying to experiment how to do all PCB design steps. I am at - how to distribute footprints after Netlist will be read.

Working under F11 I have:

  • opened pic-programmer demo project,
  • moved some elements off board (one on to of another),
  • selected them all
  • right-click and Align/Distribute and Distribute Horizontally

My problem is - nothing happened.
I supposed - may be they are locked.
I found their Move and Place state is “Lock pads” so I have changed all of them to “Free” but it helped nothing.

By the way: What is the difference betwean “Lock pads” and “Lock footprint”? I have read doccumentation od PcbNew and dont remember any info about it. I think you can’t move the footprint if its pads are locked - so it is the same as if the whole footprint is locked (we are at the PCB desing layer and not footprint design layer).

Just before 5.0 release I sow the information that english doccumentation is updated for 5.0 and there are only the problem with translations. So I have printed english PcbNew doccumention. Chapter 7.3 Automatic Footprint Distribution says that first I have do to be ready for automatic distribution is to select “Footprint Mode” Icon. But I can’t find it. Then in local menu I should see “Global Spread and Place”. I have also not found any info in that doccumentation about via stitching that I have read here at forum than 5.0 will support.
Now I think that it was not true that english doccumentation was updated. So it is lost of time if people translate it to other languages now.

As I din’t foun solution there I try to experiment. Align/Distribute Align to Top works - so it is not the problem of fixed footprints.
I have checked that it also works when “Lock pads” are set. So this flag doesn’t meen pads are locked on PCB.
Distribute Horizontally icon shows some distance to be used. I suppose may be I have this distance set to 0 somewhere in settings. I spend some time looking into settings. Not reading the texts but looking for the field with 0 in it and didn’t found it.

So what I am missing?


#2

Usually you can’t move the pins of a component so it makes sense to lock copper land area pads, too, relative to the whole footprint. On the other hand usually you want to move the whole footprint.


#3

Unfortunately the docs aren’t up to date with 5.0. This was in 4.0 IIRC.


#4

I see when I have footprint “Free” I can with hotkey M accidentally move separatelly its pads. If “Lock pads” it can’t happen - its good.
As I believe each software should be as simple as possible I wonder in practicall what for is the possibility to move each pad separatelly. I can imagine such need may be only one per million. So in such case I think the redefinition of footprint can be done allowing to simplify that one parametr for 999999/1000000 situations :). But it is only my opinion. May be I don’t know about users who need to move pads separatelly every day.


#5

I would guess it’s much larger. Sometimes you want to move a pad if you need to make space for other items and you don’t have much space in the board. Even more common is changing the shape or size of a pad. I don’t have long experience but this far I think I have changed some individual pads in every board.


#6

About the actual problem - Distribute uses the two outermost items and distributes the rest evenly between them. If you want a straight row from randomly placed items you want to use both align and distribute after moving some of them to good places.


#7

When I have first time noticed that it would be good if TQFP pads near corner had different shape to allow for wider track I changed all my TQFP footprints. It was more than 10 years ago. Since then I have never noticed any need to modify individual pad. So we have completelly different experience :slight_smile:


#8

Thanks. It works.
How it could have happened that I didn’t got that idea.
I am ashamed.
I just assumed that it must work as it works in Protel.
I understood to distribute as to scatter or to spread (two words taken from dictionary with no full filling of meaning).


#9

I ran into a case with a QFP where I got DRC errors in the corners. I changed the end pads to rounded to fix the DRC errors, so there are use cases for it.


#10

With V5 it is no longer recommend to use the Netlist reader.

Instead, in the main menu bar, select Tools>“Update PCB from Schematic…”


#11

I knew about that possibility, but didn’t heared that normal read of Netlist is not recommended.


#12

May be it is better solution to change that pads only if needed.
I have changed many years ago all corner pads (not only shape but also its length and possition a little) and solved that problem once forever. Because of this I have never falled into need to change individual pad shape during PCB design so was surprised what it is for.