PCB Assembly Service?

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Rochey

Well-known member
White Market Member
Joined
Jul 2, 2004
Messages
2,697
Location
Dallas, TX - Formerly UK
Hello Folks,

I'm considering getting a small pick and place machine, and starting a small sideline with the brother in law to assemble PCB's.

The kind of stuff i'm thinking of is putting down all the SMD Caps and resistors (the annoying things) but leaving the expensive IC's etc for you to put in yourselves when your ready.

Here's an open question to both end builders, and to fellow whitemarketeers who sell PCB's.

- Is there any value to end users in having the commodity side of their PCB's pre-assembled?
- Does saving you an hours soldering of the boring stuff have any value for you? (Maybe even reducing the risk of it working or not?)

I'll qualify this by saying that I understand that most boards are all through hole today on this forum, and I don't expect the world to change to SMD for their most critical signal chain. However, there is a lot of circuitry we use today where passives etc aren't in the critical signal chain (e.g. decoupling logic, microprocessors, or even some opamps).

Any thoughts?

cheers

/R

(edited: fixed some of the spelling errors, probably more around now! ;) )
 
Mike, please PM me on that one :)

I'm trying to build the business case for it, so any white market peeps are welcome to contact me.

Best Regards

R
 
I might have some interest if it makes sense for prototyping.

JR

edit- BTW putting down the ICs and tiny parts like resistor arrays are the hard part I would consider farming out.  Do you have any plans to support IC packages with pin under (BGA) or in the side of package (like QFN) ?
 
Same here.... it would be a plus if you can also supply the resistors and caps... instead of us sending reels of parts.

+1 to what JR said. The tiny ICs with the fine pins are the challenge.
 
While real contract manufacturers love to supply the jelly bean parts because that is a profit center for them, they can combine orders from several customers to get better pricing, etc. For small projects it is too much to expect (IMO).

Also, for high performance audio, even the Rs and C can make a difference, so probably best for those to be supplied by the customer if critical. Of course if Rochey gets serious about this he could list some standard parts (or high performance) he stocks, so he can earn the difference between us buying onesy twosey and him buying in modest volume.

If he has to invest a bunch more of his capital into parts, he needs to make a return on that too, so be careful what you wish for.

JR
 
 
Sorry if this is a bit OT but I have a question for those in the know:  Which type of SMD resistor is best for audio?  JR talks about high-performance parts.  What is considered a high performance resistor?  Most decent SMD resistor seem to have great precision (typ. 1% or lower) and lower temperature coefficient (not that it really matters for audio) than the ubiquitous 271 series metal film resistors from Xicon.  So... what's the story there?

Thanks,

Mike
 
I haven't done my own research but I have seen reports that larger SMT resistor packages outperform smaller packages, and there are measurable differences between brands (like Susumu.)

http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=401
a recent discussion on Waynes forum was instructive. 

JR
 
Great Feedback everyone - really appreciate it!
I'm still chewing on this, trying to work out if I can actually break even at some point.

Here's my thoughts right now. I'm still flexible, just sharing my current view.

In terms of components - I'd be stocking commodity noname parts. real jellybean stuff. Any critical SMD resistors etc. should either be listed (e.g. digikey part number) and we would source, or you could send us the parts and we'd use them.

Two business styles / options
- Prototype run option (10 board minimum) (higher setup cost, relatively high cost per PCB),
- 100 unit runs: Moderate Setup cost, fixed cost per placement

I don't see anyone here building in thousands of units in the US. :)

For those of you with experience using contract manufacturers, whats the setup costs been? (I've seen some --- but want some other datapoints)




 
JohnRoberts said:
edit- BTW putting down the ICs and tiny parts like resistor arrays are the hard part I would consider farming out.  Do you have any plans to support IC packages with pin under (BGA) or in the side of package (like QFN) ?

Hello JR, so far - the machine I have an eye on is an used unit, with the capability of doing 0603's, and devices with a pitch down to 0.8mm. I'm told it'll squeeze down to 0.65mm TSSOP (with the surface tension of reflow).

Cheers

/R
 
I just built a part footprint with .65mm pitch... and it isn't the only one in my design. That may be an older machine.

I might be tempted to use BGA and really fine stuff if i didn't have to deal with it myself.

I have gone through a few generations of prototype where I only needed one or two of each design cut.

I actually have a friend who worked for a CM, and I stopped using him for small qty because of his set up charges.

Good luck...

JR

 
John - Yeah, I had that impression.

I think proto builds will be in runs of 10off or so.

The BGA machines etc are $30K+
That runs a little rich for me.

Edit: Extra Q for John: What were the setup charges?
 
I'd have to look it up from years ago, but it was enough for me to say no mas...  I thought I was investing good money to prove out the design and component clearances (an issue with TH design), only to find out after the fact, he just had his crew hand pop the boards. I found out because they mis-inserted two parts.

It was o Only 5 ea of two different boards. Nowadays we know how cheap we can get 100^2 inches of 2 sided pcb.

Frankly placing single R's or Cs is not the heavy lifting... it's the tight pitch ICs, and pads on the bottom of chips...

FWIW on my last proto I hand soldered some .65mm pitch ICs and my biggest problem was substandard copper adhesion that cost me a pair of lifted pads. But they were on a quad resistor array that wasn't even very fine pitch, just a special pia for me. I expect the PCB adhesion issue was a few too many fish heads mixed into that batch of glue.

JR
 
 
Rochey said:
The kind of stuff i'm thinking of is putting down all the SMD Caps and resistors (the annoying things) but leaving the expensive IC's etc for you to put in yourselves when your ready.

For me the only useful service would be the exact other way around.

Passives are tedious but doable. The fine pitch multi-pin packages are where things get hairy (esp with pads/balls under the package, as others have mentioned).

Also, RF-oriented passives (think decoupling) may need to be placed close enough to chip pads as to make it all but mandatory to assemble the fine pitch devices first.

For low volumes, solder paste, a stencil and tweezers probably makes more sense. Stencils are getting fairly affordable, starting at US$25 (Pololu-US-Mylar / Eurocircuits/EU/stainless steel).

Now, if you could reliably and affordably place BGAs...

JDB.
[recently coaxed 4 undergrads (with no prior SMD experience) into building 100+ boards with a total of >5300 parts in one 13-hour day; have a look at http://www.youtube.com/watch?v=Fbxwi0KKnyY or http://www.youtube.com/watch?v=ElkBvsmj7Ps for an impression of the result]
 
Rochey said:
jdbakker said:
Now, if you could reliably and affordably place BGAs...

Whoa -- i see folks chargin $125 for placing BGA's in volume.

JD - help me understand a reasonable cost?

I'd say find out who those customers are who would pay $125 to place BGAs in volume... and work for them.

For $125 they must be taking the BGA out to dinner and a play, to get it in the mood to be placed.  :eek:

JR

PS: Sorry about  the sarcasm.. that prices sounds a little steep, certainly more than I would ever pay...Some here have reported their techs placing BGA parts successfully by hand. I'd say a stencil is mandatory and a steady hand required. It would also be useful to have rework tools JIC. I  am already dealing with pads on the bottom, so BGA is just more, and smaller, and closer together, and...... harder. 
 

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