PCB prototype vs small production run

i got a quote for 1 pcb prototype for $657 (1day), $525 (3day) $289 (1 week), a run of 25 (the amount I need) for $416 (1 week), tempting to skip the prototype eh?

no, it means if there is an error I simply will reorder the boards and toss the bad ones at a cost of $416 (total $832)

Even with this double order it is still less then my normal 3 day proto

• 1 week production 5 + 6 = 1

In the first case (without prototype) if no errors , then my total cost is only $416. I also get the final boards earlier (1 week vs 10 days), if there are errors then the final boards arrive a few days later as compared to the proto + production order(2 weeks vs 10 days).

My point was the small production runs are just slightly more then a single prototype, (for whatever reasons I don't understand, I assume its due to the labor overhead), and its tempting just to skip the "offical prototype" ...

it includes the NRE for production ($99)

you missed the point, if I have an error it simply means I will reorder the production boards and toss the bad ones at a extra cost of $416 (total $832), there is a "prototype", in this case it also happens to be the first production run (because of the low cost)

Even with a double production order it is still less then my normal 3 day proto + 1 week production $525 + $416 = $941

In the first case (without prototype) if no errors , then my total cost is only $416. I also get the final boards earlier (1 week vs 10 days), if there are errors then the final boards arrive a few days later as compared to the proto + production order(2 weeks vs 10 days).

just thought for small production runs, the option to eliminate the prototype makes some sense, of course there are many variables, if you routinely need 10 prototypes to get the thing working then the 3 day (or 1 day) prototype makes more sense to get a reasonable delivery time.

Yep - interesting economics. What are your board specs, and what PCB house?

Richard

Or, if you're going to populate the board and test in under a week, and think you can get it right first go, save $100-$200, and get 24 PCBs free.

What is the size/spec of the board?. For this sort of money, you should be able to get something about half the size of a PC motherboard, in four layer from one of the PC pooling companies. For a board this large/complex, going without the prototype is not a practical option.

Best Wishes

"I guess you have the best picture of how complex the board and how likely it is that the first run will be problem-free. "

Again, my main point was that two production runs were the same price (or lower in my example) as one prototype plus production...

Skipping the prototype ? This means you're going to repair the 25 for each error that slipped your attention.

Rene

--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Entirely typical in fact, going back to my experience in the 1970's sending out taped mylar.

Sometimes you can save a few bucks on the prototype by not having legends and solder masks. Of course then you'll discover when you buy the production lot that the legends are on the wrong sides and the solder mask is upside down!

Tim.

yep, I can see that happening, I always spec my prototype identical to my production specs... unless its an early experimental no-way-its-going-to- production board, then I will let up on the soldermask,silk, gold fingers, cutouts etc requirements

the board is fairly big >100 square inches

so

can't handle anything greater then 8x11, so thats out

can easily handle the size, but no soldermask, no silk, no cutouts, no thanks. but their regular service handles all these, lets see $393 proto (1 unit) not too bad, but production is $1802/25 units, thats 4 times my quote, you can have them.

(snip)

I think *you* may have missed Roger's point. At the prices you indicate, it's presumably a fairly complex board. The chances of it coming in OK first time are arguably not enormously high as a result of that (assumed) complexity. What you are proposing is trading off that extra error-finding cycle for the possible $$ saving. I guess you have the best picture of how complex the board and how likely it is that the first run will be problem-free.

I did this once on a small mixed thru-hole/SMD job with about 50 components. There was a lot of extra time spent checking before signing off. It did have ONE error that slipped through, but fortunately that only required a hand reflow of solder across two adjacent through-hole pins. You may be that fortunate. Of course you may not.

What board house gave you that quote?

Try these two companies below for dirt cheap prices. I've only done 2-layer pcbs with them and do a nice work.

So you gonna tell us the boardhouse? or is your cousin doing it in the basement fer ya...

offer a service at $5/square inch for double-sided, plated-thru, solder mask and nomenclature screen on both sides. They electronically combine your Gerber files with others' (and their own) to make up full panels. No minimum, but it happens on their schedule, so no guarantee of delivery date, etc. But $5/in is pretty good for that quality.

but aren't even large blank 2 layer pcb sheets dirt cheap (

Sparkfun is great for small 1x2 inch boards, its less then anyone I've seen. but my board is 12x12 inces so at $5/square inch that $720, that is by far the highest price yet, especially with no delivery dates.