Cost Comparison:Square vs Round Printed Circuit Board

[tarun172]

Hello,
         I am hoping some experienced PCB designer can help me out here. I am designing a PCB, shape round circular approx 21 mm diameter. I know that PCB manufacturers do not like to see an odd shape PCB because it increases the cost. I also know that one of the factors determining the PCB cost is PCB area. So, my question is should PCB cost for circular board be lower or more or less the same as compared to square PCB of the size 21 mm?

- Tarun

[skipjackrc4]

They will most likely charge you by the area of the rectangle that the circle fits in.  So if the diameter is 21mm, they will charge you by 21x21mm instead of pi*(21/2)^2 mm.

[free_electron]

In this case it doesnt matter. They don't like odd shaped boards because there is more routing time involved. In your case it is the opposite. A circle routes faster than a square of the same diameter as the circumference is lower.

Now, this is a ti y board... That may cost you...vyou would be better off stringing these using mousebites and milling them

[Precipice]

I'd say that for low volume, it's close enough that you don't care. For volume, you'll need to be talking to your PCB and assembly houses to make things as easy as possible for them. and they'll give you the answer that suits their manufacturing setup. For small volumes, knocking the last 3 cents off the PCB cost is a waste of effort. However, if you need a round board, you need a round board - a square one won't do, and vice versa. I don't quite understand the question, I guess.
(About the only way I can see it making any real difference is if you got your square board made in a V-grooved panel, in volume - that'd save you the routing time. It's not going to make much difference, though. In low volumes. V-grooving costs more than routing, as there's more setup involved. In high volumes, V-grooving is cheaper.)

What you really don't want to do is to get round PCBs made, and then ask an assembly house to stuff individual round PCBs. You'll need them to be in panels, possibly with tooling holes, fiducials and all the necessary stuff around the edge.

[Mechatrommer]

I know that PCB manufacturers do not like to see an odd shape PCB because it increases the cost.

they actually like it. they dont like it when they cant do the job or cant increase the price.

[zapta]

If you will panelized them you may reduce the cost compare to square. Google for 'circle packing'.

[Precipice]

Assembly houses may not be at all impressed by hexagonal arrays of boards!
I wouldn't do that without discussing it first...

[free_electron]

Assembly houses may not be at all impressed by hexagonal arrays of boards!
I wouldn't do that without discussing it first...

that's because the pick place repeat data is a nightmare to handle. it can be done but the panelisation needs to be driven from the PCB tool , not from the PCB maker. The pcb tool can the spit out the pick place data for the step and repeat.
if panelisation was done by the board house then no such data is available. they step and repeat gerber. they have no access to part coordinates.

[tarun172]

All,
    Thank you for your contribution. There was not a whole lot of price difference in square vs circular circuit board (just few dimes). Since volume was very low; it did not really matter. I ended up using a circular PCB design. 

- Tarun