I am designing a PCB for a raspberry pi CM4. I am using a symbol+footprint that does this as a single unit. For manufacturing I need to assign two of the same connectors to a single footprint, essentially turning them into two footprints.
I previously manually removed the cm4 footprint and manually added the 2x hirose connector footprints with before exporting the gerbers and place files which seemed to work, however this also looses all net information and theoretically completely messes up DRC since none of the wiring makes sense anymore.
Is there a way to turn this into two components without messing up the nets, or having to redo the schematic?
Single footprint which is actually 2x Hirose connectors from the point of view of the pcb manufacturer.
If understand well I suppose I would do 3 footprints.
One with holes and drawings at fab layer showing me exactly where to put two connectors that would be separate footprints.
At schematic I would use simple connector symbols adding extra pin information as a text or made special symbol for one connector and the second for second connector.
Yeah. I’m trying to avoid having to manually re-define the CM4 pinout on the schematic if it take apart the existing one. But I might have to duplicate it and make a left and right version…
The symbol i’m using has managed to show the two sides as separate symbols. But it’s still a single “unit” / “component”
Best I know, there is no way to assign two footprints to a single (multi unit) schematic symbol.
The simplest workaround is probably to put a second footprint on the PCB and lock it in place. Because the first connector already has all the pads, the second connector should not have any pads at all. Just some graphics to allow you to manipulate and align it.
I am an absolute beginner in PCB design and I am astonished there is no standard way to design a pcb for (a) component(s) in a socket. Quite a lot of components are sitting in sockets and what about a simple distance holder, e.g. for a LED, or a cooling clip for a (power)transistor? I have seen many posts on Internet where people struggle with complicated work-arounds (tricks) to get this done, but nothing in an elegant way.
The initial assembly is the placement and soldering of components to the PCB.
Components in sockets are not soldered to the PCB; only the socket is fitted to the PCB.
The distance holder for the LED is specified in the assembly instructions, along with the distance holders part reference. These days LEDs are usually fitted to the PCB with light pipes directing the light to the outside of the case.
Transistor cooling clips are fitted in a later process, after initial PCB assembly, just as components are fitted to sockets, in a later process, after initial PCB assembly.
For example: Open a brand new PC mother board box and observe. Where is the CPU? Not in the socket. Where are the Rams? not in the sockets. Where are the plugs from the power? Not in the sockets.
Final assembly is carried out by someone, by hand, following detailed written instructions. This is how all PCBs are assembled: various detailed instructions for various processes.
There are various videos on youtube showing various PCB assembly processes. It would be worth searching and viewing by you.
CPU’s are usually placed in (zero-force) sockets. Mass produced pcb’s are usually not assembled by hand but by a pick and place machine. Every PC-motherboard has one or more connectors to connect to a power supply. I am an absolute beginner in PCB design, meaning: design by myself, but a am not a beginner in electronics.
What I was writing is that the design, manufacture and first assembly of a PCB stops at the sockets.
Anything needed to be placed in the sockets is an additional process that needs separate documentation. Items that plug into sockets are not generally shown as part of a PCB. They are shown as some additional layer.
A PCB assembly house neither knows nor cares what goes in sockets, unless you specifically ask for the sockets to be stuffed. If you want sockets stuffed you supply stuffing documentation as to what components are required and where they are fitted.
But CPU’s are not inserted into sockets to go with PCB into oven for reflow soldering. So it is certainly not done in the same P&P process.
It seems being rather a part of device designing (like for example case designing basen on PCB) and not a part of PCB designing.
@jmk and @piotr: But then you don’t get a realistic 3D picture. And you cannot simulate the circuit. @Piotr: I agree that it’s a different P&P process.
Simulations are made from the Schematic, not the PCB.
I don’t bother with 3D, so I cannot comment. Maybe there are ways to add ICs, plugs and modules to sockets for a 3D image. Others may comment.
The only reason I used PC mother board as an example is because it has sockets for modules, at least one IC and plugs.
The PCB maker doesn’t give a rats about the purpose of the PCB and the assembly house doesn’t care about what goes in the sockets, unless you ask them to stuff those sockets.
To get 3D picture I would add IC into schematic and at PCB but with special footprint having no pads and with IC 3D model positioned not directly at PCB but little higher so when both models will be placed the IC would be in socket.
That I didn’t took into account. It have never happened to me to simulate the same circuit as I use for PCB so for me the simulation projects are separate once.
