Multiple PCBs from a single project/schematic

Mark Hancock schrieb:

We have a muti-board system that uses 13 boards connected using

board-to-board connectors.

Presently this means 13 different projects each with their own schematic

and pcb design.

While this makes PCB fabrication easier, it makes following a signal

trough 13 different schematics very difficult and people are

complaining.

 

One solution idea was to combine all the schematics together on a single

large sheet so it is easier to follow. 

We would have to be careful with signal names (esp power and ground) to

make sure the nets stay isolated; but, I believe it is doable.

The question is, if we ca do that, could we then route all 13 separate

PCBs using that one schematic?

Of course, but in one single board file.

It is likely that you want to design the boards as a panel right from

the start, then they can be produced and assembled as panel in a single

process.

If so, what would the challenges and limitations of doing that?

Has anyone done this before?

Yes, but it depends on the type of project if it really helps.

Take care that for EAGLE, your design is a single file. Part designators

and net names etc. are (and must be) unique. Note that then the

signal names also can't be traced between different boards, so people

will keep complaining...

Another approach is putting the boards in separate /files/ within one

/project/, and later combining only the boards to a panel for PCB

production. That's an additional step however, and you need to take care

that the panel is up to date when you start a PCB run... On the other

hand, you can use "global" net names then. (Using unique part names

makes sense here too, BTW.)

Tilmann

Mark Hancock schrieb:

We have a muti-board system that uses 13 boards connected using

board-to-board connectors.

Presently this means 13 different projects each with their own schematic

and pcb design.

While this makes PCB fabrication easier, it makes following a signal

trough 13 different schematics very difficult and people are

complaining.

 

One solution idea was to combine all the schematics together on a single

large sheet so it is easier to follow. 

We would have to be careful with signal names (esp power and ground) to

make sure the nets stay isolated; but, I believe it is doable.

The question is, if we ca do that, could we then route all 13 separate

PCBs using that one schematic?

Of course, but in one single board file.

It is likely that you want to design the boards as a panel right from

the start, then they can be produced and assembled as panel in a single

process.

If so, what would the challenges and limitations of doing that?

Has anyone done this before?

Yes, but it depends on the type of project if it really helps.

Take care that for EAGLE, your design is a single file. Part designators

and net names etc. are (and must be) unique. Note that then the

signal names also can't be traced between different boards, so people

will keep complaining...

Another approach is putting the boards in separate /files/ within one

/project/, and later combining only the boards to a panel for PCB

production. That's an additional step however, and you need to take care

that the panel is up to date when you start a PCB run... On the other

hand, you can use "global" net names then. (Using unique part names

makes sense here too, BTW.)

Tilmann

Tilmann

It is likely that you want to design the boards as a panel right from

the start, then they can be produced and assembled as panel in a single

process.

Interesting point, only a one small group of the boards are currently pannelized together (the jumper boards).

Other than that, all the PCB are ordered separately (this is a low volume internal product) .

Note that then the signal names also can't be traced between different boards, so people

will keep complaining...

That is kind of what they are complaining about now.  The techs that maintain the systems work in a clean room environment; so, they can't use paper schematics.  Trying to trace a signal through 13 schematics is driving them (and me) nuts. Going to a single sheet schematic where the associated connectors are adjacent would allow them to trace the signals on a single sheet (displayed on a monitor).

The goal is not around the PCBs.  The existing design produces the PCBs fine.  The problem is the use of schematics for troubleshooting.

Mark

Mark Hancock schrieb:

It is likely that you want to design the boards as a panel right

from the start, then they can be produced and assembled as panel in

a single process.

 

Interesting point, only a one small group of the boards are

currently pannelized together (the jumper boards). Other than that,

all the PCB are ordered separately (this is a low volume internal

product) .

Particularly if this is a low volume product, you should really think

about panelizing. It is much more cost efficient.

The goal is not around the PCBs.  The existing design produces the

PCBs fine.  The problem is the use of schematics for

troubleshooting.

From the OP, that was not clear to me...

Of course you might draw the schematic as a single sheet (and probably

some indication for the areas of the different boards). However, then

all the parts will definitely also be on a single "board" (i.e. file).

You could either generate 13 copies of the schematic and delete all but

one boards parts before designing the boards separately, or layout the

boards as a panel. I would strongly prefer the latter, because the

former is pure horror for maintainance...

If you like to use global net names, the connections between the

differents boards within the panel will remain as airwires - you need to

be extremely careful to not overlook any /other/ unrouted airwire

elsewhere on the panel when ordering a run of PCBs... It might be better

to use generic net names that contain some kind of board ID.

Tilmann

Tilmann wrote:

 

 

Particularly if this is a low volume product, you should really think

about panelizing. It is much more cost efficient.

 

     The PCBs as different thicknesses; so, I don't believe we can pannelize multiple board types together.

The PCB house I am sure must pannelize for their fab.  Typical order size is 10-20 systems.

Since these are fixtures used for volume production, each one is used to make so many products that the fixture cost is almost irrelevant.

What costs way more is fixture down (repair) time as that can affect production throughput.

Tilmann wrote:

 

 

 

You could either generate 13 copies of the schematic and delete all but

one boards parts before designing the boards separately, or layout the

boards as a panel. I would strongly prefer the latter, because the

former is pure horror for maintainance...

This would lose the connection between the PCB and the SCH.  They techs want that so they can correlate signals to traces.

CadSoft Guest wrote:

 

 

Why combine these at design level? Im sure there is a tool to combine

several prints into one http://www.element14.com/community/bigsheet. I assume you will need a printing

house to do that job, and I'm sure they can help. CadSoft Guest wrote:

   The schematics need to be combined at the design level so that associated connectors are adjacent to make it easier to trace signals.

Doing a post process to merge the drawings is an interesting idea; but, it probably would not meet what the techs want.

Also, post processing would lose the connection between the PCB and the SCH.  They want that so they can correlate signals to traces.

CadSoft Guest wrote:

 

 

But I do see some advantage maintenance, but only if the 13 designs have

much in common.

The boards are all highly interconnected.  Not my design.  At this point, I can't really change the physical design, only the drawings.

Mark