[kicad-users] Anything to watch for "with pick and place"?

[[e-mail] [kicad-users]]

Thus far, I've only done plain PCBs with KiCad.

I was wondering how the pick and place machines choose the "landing zone" for the part - is it a question of basic co-ords from a file, then camera recognition?

I ask because - in Footprint Editor -I often associate (0,0) with, for instance pin 1, especially for parts with an even number of pins. Sometimes though, I place the part's geometric centre (assuming that is easy to determine) at (0,0).

In summary - a footprint's "0,0" datum is not necessarily a good place for a machine to 'grab' the part.




BTW: If & when I do try pick & place, I was thinking of using ITEAD - I'd be interested if anyone out there has used their PCB population service?

[Clemens Koller [e-mail] [kicad-users]]

Hello!

Usually the pick&place position of the components is roughly the center of gravity which is usually the geometrical center of the footprint.
If the component cannot be picked at that place, you need an offset / an pick&place origin.

Usually, assembly houses know all about this and add their offsets + zero orientations from their databases.
There are i.e. some pressure sensors like Amsys MS5803-xx with a very soft surface which cannot pick/placed with a normal nozzle at all.
The assembly house can order a version with a pick&place pad on top (i.e. capton tape covering the sensor opening) to be able to use a normal
p&p nozzle - or they use a nozzle with a special opening or a grip to handle these things.

Placing the origin of the footprint to the center of pin 1 is IMHO not very useful.

Regards,

Clemens

Post by ***@yahoo.co.uk [kicad-users]
Thus far, I've only done plain PCBs with KiCad.
I was wondering how the pick and place machines choose the "landing zone" for the part - is it a question of basic co-ords from a file, then camera recognition?
I ask because - in Footprint Editor -I often associate (0,0) with, for instance pin 1, especially for parts with an even number of pins. Sometimes though, I place the part's geometric centre (assuming that is easy to determine) at (0,0).
In summary - a footprint's "0,0" datum is not necessarily a good place for a machine to 'grab' the part.
BTW: If & when I do try pick & place, I was thinking of using ITEAD - I'd be interested if anyone out there has used their PCB population service?

[[e-mail] [kicad-users]]

I have asked assembly houses what they prefer for a number of aspects of PCB design and the typical answer is they will work with what they are given. My understanding is the "standard" coordinate reference point for parts is the centroid which makes sense, that's the point used to pick up the part. For 99.9% of parts it is the center of a rectangle. For the remainder of the parts you have to figure it out or just use the center of the biggest body of the part. If it only had leads on one side they likely won't impact the center of gravity much unless they are long.

I don't recommend using pin 1. Even then you still have to find the *center* of pin 1 and that just complicates the issue.

I think they will work with what you give them, but be careful about specifying rotations. They don't always check their work and can screw that up.

Rick C.


---In kicad-***@yahoogroups.com, <***@...> wrote :

Thus far, I've only done plain PCBs with KiCad.

I was wondering how the pick and place machines choose the "landing zone" for the part - is it a question of basic co-ords from a file, then camera recognition?

I ask because - in Footprint Editor -I often associate (0,0) with, for instance pin 1, especially for parts with an even number of pins. Sometimes though, I place the part's geometric centre (assuming that is easy to determine) at (0,0).

In summary - a footprint's "0,0" datum is not necessarily a good place for a machine to 'grab' the part.




BTW: If & when I do try pick & place, I was thinking of using ITEAD - I'd be interested if anyone out there has used their PCB population service?

[Jean-Paul Louis [e-mail] [kicad-users]]

Rick,

Your statement is correct if you use ONLY SMT parts. In that case the centroid is what is best for SMT placement machines.
BUT, if you use throughout hole parts, you want always use pin 1 as thought hole insertion machines always use pin 1 as reference.

Just my $0.02,

Jean-Paul
N1JPL
40 years of experience in electronic manufacturing

Post by ***@arius.com [kicad-users]
I have asked assembly houses what they prefer for a number of aspects of PCB design and the typical answer is they will work with what they are given. My understanding is the "standard" coordinate reference point for parts is the centroid which makes sense, that's the point used to pick up the part. For 99.9% of parts it is the center of a rectangle. For the remainder of the parts you have to figure it out or just use the center of the biggest body of the part. If it only had leads on one side they likely won't impact the center of gravity much unless they are long.
I don't recommend using pin 1. Even then you still have to find the *center* of pin 1 and that just complicates the issue.
I think they will work with what you give them, but be careful about specifying rotations. They don't always check their work and can screw that up.
Rick C.
Thus far, I've only done plain PCBs with KiCad.
I was wondering how the pick and place machines choose the "landing zone" for the part - is it a question of basic co-ords from a file, then camera recognition?
I ask because - in Footprint Editor -I often associate (0,0) with, for instance pin 1, especially for parts with an even number of pins. Sometimes though, I place the part's geometric centre (assuming that is easy to determine) at (0,0).
In summary - a footprint's "0,0" datum is not necessarily a good place for a machine to 'grab' the part.
BTW: If & when I do try pick & place, I was thinking of using ITEAD - I'd be interested if anyone out there has used their PCB population service?

[[e-mail] [kicad-users]]

Many thanks to all for your replies.

A bit depressing for me, as I'll need to change a lot of parts...

I'd used non-central origins for at least 2 reasons

1) Can be easier to locate things relatively - especially if like me you do a lot of 0.1" grid breakout boards.
2) With an even # pins, the centre is not on a pin. Then I need a 0.05" grid to place the part such that a pin lands on a 'dot'.

(Zooming so that I see one dot per 0.1" is useful for quickly checking relative distances in 0.1" units, and confirming all header/breakout pins do indeed land somewhere on that grid).

Anyway, glad I asked, and it does make sense what you all say.

Cheers
Stephen.