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JohnsonMiller , 08-10-2016, 06:20 AM

Hi,

In the OpenRex design, there is .Designator in the center of components and in a mechanical layer, what is it, and what it does? For which design phase it is needed?

mairomaster , 08-10-2016, 07:25 AM

It is a special string. When you have the special strings replacement enabled (hit L -> View Options -> Convert Special Strings) the strings gets converted to the particular component designator. That allows you to have the component designators available on a mechanical layer as well. Normally that is used for assembly drawing of the board with all top/bottom components. You can't always use the silk screen for the purpose, because you don't always have space for all designators on the silk screen layer for example.

robertferanec , 08-10-2016, 09:25 AM

Excellent answer @mairomaster

JohnsonMiller , 08-16-2016, 01:50 AM

Thank you for explanation, some related question:
1- the original libraries of altium does not come with this feature, should we add it manually? Indeed I hate to edit this libraries at all.
2- along with the .Designator, do we need to add component shape or some graphics to the related mechanical layer?
3- Is this useful method invented by you or it is standard method along industry?

mairomaster , 08-16-2016, 03:51 AM

If you want to use it, you need to add it to all footprints in your libraries manually. You just need to decide if you want to have nice assembly drawings or not. It is not a big thing in my opinion, I barely use my assembly drawings, but it could be a nice touch if you/somebody else needs the assembly drawings at some point.

About the layer, you can do it in different ways. I have 2 different layers - one with the designators and another one for the components courtyard (outline). I believe Robert normally uses a single layer for both the courtyard and designators.

I know the method is kind of popular with Altium at least, since it seemed to be the best way to generate assembly drawings. Now they introduced Altium Draftsman which provides an alternative, you can check it if you have Altium 16.1.

robertferanec , 08-16-2016, 06:46 AM

I would like to add to the @mairomaster's answer, that we create the assembly drawings mostly for assembly house. I have seen assembly houses using the assembly drawings a lot. Also, these drawings are useful for board debugging or in test department.

I am not sure if I invented it, I guess a lot of people use it the same way, I just needed a layer with clear component position. Before, I used to use Silkscreen layer, but as our boards went smaller and more packed, there was no way to fit all the designators on the Silkscreen layer and we had to find a different way - so that's why we do it.

JohnsonMiller , 08-17-2016, 08:33 AM

thank you, got it.
I have started updating my own library,

around standard components of Altium there is a green line, if I change the density this green lines move, along with it there is a cross in the middle of component, sample screenshot attached. what is this green line?

Regarding pick&place machinery, should we set the component origin?

mairomaster , 08-17-2016, 08:51 AM

The green line is the so called component courtyard used for the assembly information. It's purpose is to show you how close to each other you can put two components. The green cross shows the origin of the footprint. In my libraries I have it on a separate layer. It is not mandatory. I am not really sure how practically useful it is. The assembly houses can do alright without it.

robertferanec , 08-19-2016, 11:53 AM

I just would like to add. The component origin is used when you are generating Pick&Place file, so you may want to place the origin at the point where the machine should hold the component. Normally, for SMT components we place the origin into middle (center), for through hole components (which are assembled manually) we place origin at the pin 1 (it's easier for documentation and mechanical drawing, as through hole components are usually connectors)