Component Designators on multi-pcb projects

[scgreenhalgh]

Hi All, long time lurker, first time poster (so please be gentle).

I am currently working on a project that goes over multiple PCBs for the first time and realised that i don't know what the "standard" or best practice for component designators over two (or more) boards. Do designators start over on each board, do they have like a earlier designator (i.e. board one R001- R099, board two R101-R199, etc)?

The boards are going to be panelized and sent off to a pick and place in china, so how would it work if you had two boards with designators that start again?

Thanks!

[alexanderbrevig]

Depends on your software.
As a matter of precaution I would have the next board continue from the previous.

With kicad I made a script that appends a suffix so that board 1 could have A after everything and board 2 could have B.

Which CAD are you using?

[tycz]

scgreenhalgh,

I wouldn't put two different designs on a production sub-panel. I think its better to let the factory handle panelisation, but if you do it yourself you should ask the factory about details like this.

[scgreenhalgh]

@alexanderbrevig I am using Altium Designer 18, this allows for multi-pcb projects but treats the pcbs as individual projects.

@tycz we have typically done this to allow us to use a single stencil for both boards (and make one full device at a time), but good idea to check with the manufacturers doing the assembly.

[Mattylad]

I would keep each board in its own right, R1 on each.
It's easy enough to differentiate between R1 on board A, board B and so on.
Why?
Higher numbers in reference designators takes up more space either on board or on assembly drawings.
If you have Board A use R1-R99 then what do you do if in the future you actually find you need 102 resistors on board A?

All panelized separately.
Why?
Because poop happens, boards need updating and issues raising.
If you have them on the same panel then you will have to redo the entire panel for all of them.
If during a production run you have mishaps with some boards then you may waste the entire panel if you have multiple boards on the same panel.
i.e. if a design has 4 boards in then you have 4 panels. If 1 board is wasted in a production run then you get left with 3 boards that cannot be used.

Can your stock control system handle 4 boards on one panel? I always got complaints from goods inwards - "what do we book these in as?"
Then there is what do they book out? What about making service/repair stock of a single board (perhaps the one most likely to get damaged in service).

Board houses can handle the above easy enough, they can handle the opposite easy enough. ask them.

[Chris56000]

Hi!

I recommend a method that two former British TV makers, RBM and Rediffusion/Doric used, as well as B & O in the 1970s & 1980s, and that is to prefix every reference with a number for each PCB, for example, suppose you're making a Curve Tracer with four boards and some chassis/case wiring,

you could have:–

1) Case wiring – On/off switch 0SW1, mains fuse 0F1, etc.,
2) Power supply for collector:– 1R1, 1C1, 1D1, etc.,
3) Step Generator:– 2R1, 2C1, 2D1, etc.,

This method has the advantage of starting every board/unit/sub–section at 1, and unlike three–digit references "Rxxx" you not stuck if you've got over 100 components of a given type!

Incidentally it's not necessary to number each section 1R1, etc., a simple text note on the circuit/pcb stating "Component Prefix 1" etc., is all you need!

Chris Williams