It was fun to meet everyone who attended the robotics meeting at pololu last night. Since I ageed to report the [predicted] “demise” or “crash and burn” of my project step by step, the following describes what happened today. Hopefully this information will be helpful someday to someone [trying to be] as stupid as me.
#1: I received a sample of the stick-on BGA alignment product that I mentioned at the meeting, which includes:
___ A: a tiny PCB with BGA pads (and nothing else)
___ B: a matching BGA component
___ C: the alignment stick-on
My first impression is: this will work quite reliably for attaching BGA parts to PCBs, whether the BGAs are soldered with a reflow-oven or a hot-air gun.
It is easy to attach the stick-on gizmo accurately and quickly over the BGA pads. And when you slide the BGA part over this gizmo you can very definitely feel the part fall into the holes — no question about it… the part is seated where it is supposed to be.
You guys should get a sample, because you can make these too (!!!much cheaper!!!), and because of that you can start to make gizmos with BGA components! That should open up a few new possibilities, perhaps. Click the various links under “learn more” on this page: http://www.solder.net/stencilquik/datasheets.asp … and order yourself a free sample and draw your own conclusions!
#2: I called aapcb.com to ask why their quote to assemble my PCBs is more than one week late. At the meeting, some folks seemed to think they want to avoid dealing with my BGAs and/or tiny-pitch QFNs. The reason they gave me for the delay was “a major surge in requests for quotes”. Who knows if that’s true, but at least I got to ask the question that seemed to worry many folks at the meeting - whether most or all the PCBs they assemble would have shorts, opens, overheated and degraded/trashed components, etc. In other words, there was worry that perhaps not even ONE of my 25 larger (5.80" square, 300 component) PCBs would be soldered/assembled correctly. So I asked the question, “Do you know what percentage of BGAs or QNFs you solder will have shorts, opens, flaky connections or damaged components?”. Her answer was, “we experience less than ONE improperly soldered BGA or QFN component per month” (for all customers combined).
Sure, maybe I can’t believe them, but that’s astronomically different from “most BGAs (or PCBs) will have soldering defects”, which seemed the consensus of the folks who had an opinion about this. Or maybe I should substitute “worry” for “consensus”. Bottom line: Now I certainly have this issue bracketed - 0% success to 99.99999% success. Surely the truth falls somewhere in that range!
Woops, I just received the quotes by email. Remember:
ice-eye == 2.80" square PCB with image sensor and ~50 capacitors.
ice-quad == 5.80" square PCB with FPGA, CPU, PHY (300 components total).
25 ice-eye == $2600 @ 10-days : $3000 @ 5-days (with stencils, programming, etc)
50 ice-eye == $3000 @ 10-days : $3200 @ 5-days (with stencils, programming, etc)
25 ice-quad = $5200 @ 10-days : $5600 @ 5-days (with stencils, programming, etc)
50 ice-quad = $7800 @ 10-days : $8200 @ 5-days (with stencils, programming, etc)
The stencils, programming and other “bogus charges” costs about $1000 for each PCB, and is included in the above prices.
Since I am willing to wait to save $$$, the bottom line is $3000 + $5200 = $8200.
For $8200 I can buy an entire full-bore zephertronics system like the “3LMZT-7-BG” system described on tiis page: http://www.zeph.com/systems.htm, including nozzles and such. Then I have all this equipment to build and repair other stuff. Also, as Jan correctly mentioned, zyphertronics tends to overcharge for their equipment, and cheaper options also exist. The following links show a few alternatives from “Madell”, though clearly they are missing several items included in the zephertronics system.
$ 520: http://www.madelltech.com/m3-16.html.
$ 625: http://www.madelltech.com/m3-13.html.
$ 755: http://www.madelltech.com/XBoxBGA.html.
$2350: http://www.madelltech.com/m3-17.html.
The hot-air gun stand alone is here:
$ 300: http://www.madelltech.com/m3-5.html.
I mention this stand/press gizmo separately because I prefer other hot-air guns I’ve seen on amazon.com, but I haven’t found another stand yet. I think $300 for a trivial little stand like this is preposterous, so I will keep looking. I can buy an entire benchtop drill-press for $300, build a bracket to hold the hot-air gun, and end up with something much sturdier and more flexible. Also note how the gizmo is designed so the hot-air gun cannot be positioned very far from the vertical post, so components more than about 4" from the edge of the PCB cannot be reached. Not smart!
The systems mentioned above are essentially “rework stations”, though obviously they can also assemble a new PCB from scratch — one component at a time.
The alternative to “one component at a time” rework systems like the above is some kind of “one PCB at a time” system. Essentially, a “one PCB at a time” system partly or fully implements (or fakes) a nominal production syste albeit on a smaller scale. The basic elements of this approach are:
#1: solder-paste stencil printer
#2: pick-and-place machine
#3: multi-zone reflow oven
#4: cleaning system
#5: inspection system (stereo microscope [and xray imaging])
#6: rework system (to fix defects == essentially the alternative system above)
At least, the above is what I have come to infer is a “production system”. Here are the various ways I have found to implement and/or fake each of the above.
#1: solder-paste stencil printer
___ A: solder-paste dispenser ($20 plunger to $800 with air-pressure)
___ B: plastic sheet stencils ($100 ~ $200 for both PCBs)
___ C: stainless-steel sheet stencils ($200 ~ $400 for both PCBs)
___ D: stainless-steel framed stencils ($300 ~ $600 for both PCBs)
___ E: manual stencil printer system ($500 ~ $2000)
___ F: automatic stencil printer system ($2500 ~ $15,000)
#2: pick and place machine
___ A: human hands + vacuum pick-up tool + stereo microscope ($700)
___ B: manual pick-and-place machine ($1500)
___ C: automatic pick-and-place machine ($50,000 to $250,000)
#3: multi-zone reflow oven
___ A: pre-heater - to heat bottom of PCB ($800 to $3000)
___ B: hot-air station/pencil/gun + nozzles ($300 to $1300)
___ C: crapoid 1-zone reflow oven ($1000~$1500)
___ D: quality 1-zone reflow oven ($4500~$5500)
___ E: multi-zone reflow oven ($8500~$25000)
#4: cleaning system
___ A: no-clean solder-paste
___ B: not sure
___ C: not sure
#5: inspection system
___ A: stereo microscope with dual boom stand ($500 ~ $2500)
___ B: xray system ($no_idea)
#6: rework system
___ A: zeph system + nozzles + templates ($9000 ~ $12000)
___ B: cheaper versions of the above ($1000 ~ $5000)
#1: At the moment, I’m VERY uncertain how important it is to buy a quality manual or automatic stencil printer system… versus simply buying the stainless-steel stencils with folded-up edges. Maybe I’ll try the “cheapskate” folded-edge stainless-steel stencils technique, then buy something more expensive if that’s problematic.
#2: I’m stuck with option A ($700) until the product generates enough earnings to buy a $50K ~ $100K automatic pick-and-place machine.
#3: Probably I’ll buy options A and B for rework, and possibly C too. I prefer the reflow oven solder 1000 joints all at once, unless I find I can assemble prototype PCBs quickly and reliably with options A and B.
#4: Until I learn more, option A is all I know.
#5: I’m definitely buying option A because it is so generally useful for so many purposes. I need to learn more about option B if more than a small percentage of PCBs have assembly problems.
#6: I’m inclined to go with a mix of option A and B, and maybe even build all prototype PCBs with only the “rework system” and no reflow-oven.
or 
or 
… TBD.