Single design vs MultiDesign boards pricing

[anishkgt]

Hi All,

Just thought of asking this question in the community than to a Fab house.

So would it be cheaper to have individual boards done or two designs in one panel. my eagle license is limited to standard so i can't add another board to it.

[rea5245]

Different manufacturers have different policies. The answer can also depend on the sizes of your two designs, since any surcharge for multiple designs is likely to be a fixed fee, independent of size; whereas the cost of manufacturing the designs separately will depend on their size.

First, if you want the different designs cut apart, or if you want a V-score cut between the designs, the manufacturer will always charge you extra. Whether it will be more than submitting two board orders will vary from manufacturer to manufacturer and the size of your designs.

But if you want to put two designs on a single board, with nothing (except, perhaps, a silkscreened line) between them, it's still complicated! Some companies will not add an extra charge and some will. I've found that customers get annoyed at the companies that add the surcharge, and they don't understand the rationale behind it. E.g. if I'm paying for a 10cm x 20cm board, why does the manufacturer care if I have one design on it or two? The answers from the companies are frequently unsatisfying.

I run PCBShopper.com, which is a price comparison site for PCB manufacturing. You enter your board's specs and my site shows you prices from up to 25 different manufacturers. I got enough complaints about this multiple-design issue that I added a "number of designs" field to my form. Now, you specify how many designs are on your board and PCBShopper's price results will show how much the companies will charge, taking into consideration their varying policies.

In short, there's no one-size-fits-all answer to your question. You need to choose a manufacturer and go to them (e.g. use their automated on-line quote form) to price out your options. Or, use PCBShopper to quickly see results from 25 different manufacturers.

- Bob Alexander
  PCBShopper.com

[anishkgt]

Thanks bob I’ve used pcbway and allpcb of which allpcb seemed cheaper. I guess will have to check with them first.


Www.Georgehobby.wordpress.com

Equipments: DSO104z, Hakko FX888D, Brymen BM869s

[phil from seattle]

I can understand the manufacturers trying to squeeze the profit out.  It's a very competitive business right now and I don't begrudge those that have the 1 design per board rule. 

By the way, it is possible to sneak that kind of panelization by them but I don't bother. The boards are so cheap to begin with.

[KL27x]

The common FR-4 and polyamide size that my manufacturer uses appears to be something approaching 9"x12". This seems to be what they prefer, unless for extra large pcb.

If you print out your boards on paper and cut them out, you can see how many you can fit on a sheet of printer paper.

Board A, only.  Say this is 24 pcb. This is 4.2% of a panel per board
Board B, only   Say this is 18.        This is 5.6% of a panel per board
Separately, this comes out to 9.7% of a panel per board.

If you can get that number lower by putting 50% board A, 50% board B on a single panel, then you might be able to save money.

But also consider these things, from a manufacturer's perspective:

For electrical testing, a combination panel may have an extra charge for each additional board. I don't think you avoid many/much in charges. And to test both boards in same pass, it requires more complex jig. They might end up testing the two different boards in two separate passes.

Drill sizes and router bit sizes. If one board requires drill bits that aren't needed on the other, this means they have to do more drill bit changes, overall.

Assembly: This increases logistics. You can't make a panel unless you have ALL the parts. You can't do Part A while waiting on Part B. And you need a machine that will hold all the components (or do tape changes).

On the plus side, you would save the one-time fee on a stencil.

*If your board has a weird shape, like say it's pretty much a long, thin rectangle, but with a little widget sticking up on the top towards the right corner, and a little widget sticking out on the bottom towards the left corner, I find my manufacturer will panelize this as the smallest rectangle that will fit the board, as submitted, potentially wasting a lot of space. So in this case, I may be able to save money by rotating the entire board, myself, before submitting it. This is part of my job, not theirs. 

[zeqing]

depends on the size and quantity, and the vendor production model....for me i would like to ask the vendors' quotation, which would be more precise.

[mpi]

I make small (approx. 2x2 to 3x4 cm) pcbs, all different. 9 to 12 designs can fit on a 10x10 cm PCB. I do all the work panelizing the PCBs myself (easy with Eagle) and just send them the zip with Gerbers. The PCBs are almost all different shapes, most with mitered corners. The separators are mousebites. The outlines look something like this:



I've been using Dirty PCBs with no problems, but have been looking for a "backup". Quotes from PCB Shopper and individual sites for 10x10 cm PCBs that many individual PCBs are stupid expensive, as are many tiny individual PCBs.

I don't buy the argument about electrical testing, drills, or routing. The Dirty PCBs are 100% electrically tested and I've never had a problem (although sometimes a board will be marked as bad, and then I have to check all the individual PCBs to find out which one), and my routing is pretty crazy but I've never gotten any complaints or was told something wasn't possible (but a couple times on the early PCBs I found where they added a mousebite to stiffen part of the PCB -- the shame! . I think the real reason is they don't want other companies using their services to make PCBs for individual clients.

Dirty PCBs doesn't do the PCBs themselves, but shops them to multiple fab houses. Are there no other companies that also do this?  It'd be great to find another source in case something happens with Dirty PCBs.

[xaxaxa]

I make small (approx. 2x2 to 3x4 cm) pcbs, all different. 9 to 12 designs can fit on a 10x10 cm PCB. I do all the work panelizing the PCBs myself (easy with Eagle) and just send them the zip with Gerbers. The PCBs are almost all different shapes, most with mitered corners. The separators are mousebites. The outlines look something like this:

Most pcb manufacturers mainly care about two things:
1. If the panel is difficult to handle (it is too mechanically weak)
2. (to a lesser extent) milling long slots is time consuming

With elecrow they allow putting many designs in one panel separated by slots even though their website says otherwise, if you keep your slots 2mm wide or larger and make sure the overall panel is mechanically strong. See attached example. I think most other pcb fabs are the same. In general don't put a row of holes on the connection tabs.

jlcpcb's website makes this fairly clear and on their own forum (in chinese) they stated that the policy is slots must occupy no more than 2/3 of the length of the pcb, so they are less tolerant than elecrow but they are also cheaper.

If you buy a small table saw designed for cutting pcbs (~$100 on aliexpress) then you can just put a silk screen line between sub-designs and use practically any pcb fab as they don't actually care that you have many designs on one pcb. This also has the advantage of needing less space between sub-boards (the kerf is only 0.6mm compared to a 2mm slot).

[henryinsydney]

Very good idea, cutting the boards yourself with a table saw!

[KL27x]

I have tried a few methods.

Instead of a table saw, I have used a tile cutting saw. It's a small table saw that has a reservoir for water. And it uses a diamond blade. Ignoring the other pitfalls of my cheap tile saw, the obvious suck is the wide kerf, the noise, and the water spray. Oh.. also the hand-numbing vibrations.

I have tried using a bandsaw, but FR-4 is too abrasive for steel blades. It's not worth the time of changing out the blades, let alone the cost. I cut approximately 2 feet of 0.064" FR-4 before my 100" long 6TPI blade stopped cutting and started burning the FR-4. Boy, it threw some sparks. Carbide blades might work out, but you need an 18" bandsaw (for maybe $2K) to even fit a carbide blade. And carbide bandsaw blades cost like $250.00, themselves. I have neither.

So then I built a small router table which holds a Proxxon tool (15k rpm Dremel sized rotary tool with very low runout and very low noise). I have toyed with the V groove pointed carbide cutting bits, and they won't work in this setup because the spindle speed (and/or rigidity of my table) isn't high enough. They cut herky-jerky and quickly dull. So I added a tilting mechanism so the rotary tool can tilt 45 degrees. Using a square carbide endmill tilted 45 degrees, it cuts a 90 degree V groove in FR-4 like no tomorrow. To me a tad more precise, perhaps at a feed rate of a couple inches per second with groove depth of about 0.8mm. With just an adjustable fence, it's all you need to cut straight lines. I can score a 0.032" thick FR-4 partway through so I can depanelize it by snapping it, later. Or I can chew through 0.064" FR-4 in one go, if I want; generally, I would cut halfway through and repeat on the other side, though... to keep the kerf smaller and to reduce the dust. And if you want to clean up the edges, a router table guarantees a parallel edge. Just flatten one edge on the disc sander, then route the opposite edge on the router table (with the endmill straight, of course). This is relatively low dust, because all the dust falls straight down, into the table. I don't use it with vacuum. I just sweep the dust with a brush. I feel like that's better than the vacuum possibly blowing fine particles into the air. I have cut a good bit of PCB's with it, as well as wood, plastic, and steel. I use the same endmill for 95% of whatever I cut, and I still haven't worn out the first bit.

I'm not sure if all the small to medium sized wood / plastic / aluminium working mills can even generate the right spindle speeds and have the right kinds of tool capabilities to work at the RPMs needed to cut FR4 in 1-2mm diameter slots

1-2mm slots? Probably not at any reasonable feed rate. I can cut perfectly straight slots in FR-4 with an 1/8" endmill. Or even with a slightly smaller carbide drill bit. But the slot has to be slightly larger than the bit, so I can make a clean finishing pass in either direction. And I need to have a reference edge that is parallel to the slot. As aforementioned, the max RPM on my Proxxon is only 15K. Most Dremel tools go up to 25 or 30K. With my setup, this is nominally 3mm thick at the minimum, and this is quite a bit slower than the turbo-tilted-V-groove. 2mm sounds unlikely with a standard rotary tool and a straight endmill. But do the math on a 90 degree V groove going say 1/3 the way through the thickness of your board on either side, what does that come out to? About 2/3rds the thickness of the board, methinks. Winner, winner.

Edit: as for cheap guillotines, I find they will work on FR-4 max thickness of 0.032" which I think it 0.8mm? The cut tends to veer away from the cut line, and the board tends to be left curled, a bit. Better on 0.020 and thinner, IMO. If you wanted to cut thicker board, and the curl (internal fracturing) damage isn't an issue, I would think aviation tin snips would do the job.