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To stuff or not to stuff


#1

I have a delima. I have 2 pcb designs with 50+ components each. Based on the pcb assembly quote I could buy a rework station on the cost of just 1 spin of 1 design. If there is something wrong with the design then I’m out the cost if the assembly + components; and I don’t want to do that.

The question is: should I get the rework station and stuff the first few spins of boards myself ( no I can’t find someone locally to do it)?


#2

how many boards do you need to make in prototyping, and for real? How developed is your board - how confident are you that this should work?

Paging @Justin who has a picknplace that may not get much use??

Personally, I’d always do prototype boards myself, but I’m a tightar$e. 50 is not that much - I’ve modded a toaster oven for reflow, and I have an SMT hot-air gun (not a rework station) which is good enough for most things needed, except fine pitch, small amounts of solder etc… then I’m screwed.

The cost in doing small run boards is the setup time on a machine - the NRE, non-recurring engineering time - making the pnp know how to grab the component, and put it in the right spot/orientation. Doing that takes X minutes/hours, and they then have to recoup that cost spread out over your job - which in a small run prototype could be as little as say 10 boards, making the per-board cost very high. Since it’s a prototype, that NRE is wasted unless your board was perfect, then they need to have minimal setup time for doing a production run. So your challenge is making the NRE actually NR, and you can do that through spending money (with them to do tests) or through labour doing the assembly yourself the first time


#3

@Brett, Since there are 4 types of boards and I need to build at least 3 machines to prove that I can manufacture them, that means a total of 12 boards that must be stuffed. I’ll be getting the pcbs in batches of 10.

For real, I’m looking at making 104 machines; 416 boards + extras in the event of breakage, and to offer them as a product outright).

Edit: On board has $40 dollars worth of components on it, another has $100 dollars. The third and forth, I don’t yet know.


#4

for a run of 10, your NRE will kill you unless you can pimp out the work to someone cheap. @justin is cheap, but I am not sure me pimping him out like this is cool with him :slight_smile: So really your only first-run option is to do a hand-stuff run on one or two to prove the design works, then scale out to the remainder of your 10 boards (assuming it runs) to get your three working prototypes.
NRE. At some point, you have to pay it. You’d want to be sure the 104 (call it 120 for manufacturing losses?) are not going to need changes before committing the NRE lock-in.


#5
  • Talk nicely to people that have made the mistakes and get them to look over your layouts.

  • Make sure your always run a DRC before creating your Gerbers for manufacture

  • Build the first board yourself with tweezers and a cheap IR oven

  • Then if all is well get one of @Brett working girls to do the donkey work


#6

he forgot one point. Order stainless steel solder stencil, even for your first board / IR oven builds. Especially if you have small pin pitches and/or close component spacing. Doing toothpick placement on small stuff sucks the proverbial - just don’t ask how I know


#7

(Brett has working girls :smirk: )

So then the advice is:-

  • Unless you know the board is to your liking, stuff the board yourself.
  • If it is good, still stuff the first few up to 10
  • Running a small number of boards through PnP is a waste of resources. Wait till I need to do 30+
  • Order the solder stencil if hand stuffing, it will save your proverbial…
  • Brett has working girls…

So if the board doesn’t work out, I should be able to scavenge the major (i.e. expensive) components from one that is not working.


#8

Send your BOM and Gerber’s to MyroPCB and ask for a quote.

I’ve used them loads of times and very good service. Very fast time to quote too and they do due diligence on your parts list to PCB layout to make sure no issues with parts.

Nothing to lose asking for a quote. They are well happy to do small runs. I’ve done as little as 4 PCB’s before.


#9

Well he has been pimping…

Yes, order a stencil. Have a look at ALLPCB if you havent.
I can run a single board thru the PnP as 90% of my BOM’s are common which use reels that dont change on the PnP. Generating the PnP files from Altium or the like is a single click so for me PnP setup generally takes 5 mins.


#10

2nd ALLPCB if you just want bare boards. Super low prices and very fast service.


#11

The boards are 4 layer; Seeedstudio is the cheapest of them all but they take forever.


#12

Only if you do a specific size maybe, but then when you add shipping…

eg.

Do a board say 110mm x 100 at seeed then the price jumps from $50 to $104 + shipping.
Same size from all PCB is $76 including DHL

Also seeed will charge extra for doing panels and v grooves etc.


#13

@Justin, and you need panels to do pick and place, singe board PnP just isn’t a thing yet.


#14

I do lots of single board pnp :yum:


#15

@Mr_John_Smith, give AllPCB a try out next time. You can get your PCB’s as a panel or you can get them as single.
I just ordered 5 off 100 x 65mm 2 layer boards from AllPCB. $20 including shipping and 24 hour (working day) service. I used to use Seeed Studio but they did not do the board cutouts. Prior to AllPCB, I used DFRobot and they were good for board cutouts etc but took far longer and more expensive.


#16

@Dave_McLaughlin, ok I’ll give AllPCB a whirl. I’ll get the stencil and some solder paste.


#17

After calculating the costs, I realized that I forgot one important element: What if the boards work the first time?

So I placed an assembly order with AllPCB. We’ll see how that goes.