Olimex A10S/A20-OLinuXino boards quite BBB-like

It's Allwinner chips with everything at Olimex!

• Announcement from their blog.
• Allwinner chips in Olimex shop.

That's a very good idea from Olimex to sell the Allwinner devices directly.

Not only does it support their official position on open hardware by making it easier for people to acquire the necessary components for their own PCBs, but by selling more of the devices, Olimex gains access to more volume from Allwinner and so brings down their own product BOM costs too.  Good plan.

Morgaine Dinova wrote:

 

That's a very good idea from Olimex to sell the Allwinner devices directly.

Interesting, but I wonder how many sales of the BGA devices they'll make. Unlike the RPF, I don't presume that it's impossible for hobbiests to handle BGA's at home, but I do think that the number who will have invested the time and effort will be fairly low. Divide that by the number who will want these particular devices and what's left ?

The other avenue is if they can supply commercial volume, but it wouldn't be unreasonable to think that anyone buying in commercial volumes will either be able to go direct to Allwinner, or will get their outsourced Chinese subcontract manufacturer to just source them locally.

So good plan, yes. But I must be missing something for this to be much more than interesting PR.

Are there places that will just fit a supplied BGA package to a PCB, possibly as part of printing the board?

If so, I can understand enthusiasts in the West being happy to pay Olimex a bit more to avoid liaising with China themselves.

Morgaine Dinova wrote:

 

Are there places that will just fit a supplied BGA package to a PCB, possibly as part of printing the board?

I dare say there are. Most of the places I've looked at in the past fall into two broad categories:

1. PCB Only
2. Give us the gerbers & BOM we'll source everything and assemble it for you

So I'm sure there's some middle ground if you can find somewhere willing to deal with very low volume prototype stuff.  I've seen places that will supply a laser cut solderpaste stencil almost for free even when ordering relatively small quantities of PCB's.  It starts to become a question of whether the setup of the paste machine, pick&place machine & reflow oven is worth it for one-off or even 10 off type quantities though.

I do seem to remember reading about some newer solderpaste machines that are more like an inkjet printer, so you can selectively do only what's required.

From memory, pcbtrain (excellent manufacturer) will put on a one-off single SMD part (e.g. BGA) for £50, so not cheap, but not completely unaffordable either. I've been working on a reflow machine for over a year now! I might finish it one day. Pcbtrain can supply a metal mask, they sent a sample a while back, it looked very nice (it was steel).

From memory, pcbtrain (excellent manufacturer) will put on a one-off single SMD part (e.g. BGA) for £50, so not cheap, but not completely unaffordable either. I've been working on a reflow machine for over a year now! I might finish it one day. Pcbtrain can supply a metal mask, they sent a sample a while back, it looked very nice (it was steel).

shabaz wrote:

 

From memory, pcbtrain (excellent manufacturer) will put on a one-off single SMD part (e.g. BGA) for £50, so not cheap, but not completely unaffordable either.

Yeah, but whatever you're doing would need to be pretty special to bother. Added to the cost of a PCB and an A20 + PMIC from Olimex and you're likely already at least double the cost of a BBB or RPi.  As a way to prove a prototype for a much bigger production run then sure.

Sounds like there's a niche for a self-soldering BGA breakout board, containing an on-board heater and clamp.

Or a socket: http://www.selwyn.co.uk/index.php?option=com_k2&view=itemlist&task=category&id=13:bga-sockets-adapters

I can imagine those sockets are probably bga's themselves and I'd be surprised if they're not insanely expensive, so 50 quid to get a one-off done may not be so bad after all.

A BGA socket that has to provide low-impedance connections purely through precision contact pressure on so many balls is a tall order both mechanically and electrically, so yeah, the price would probably reflect that.

In contrast, a breakout board or header with a built-in heater and solder pads wouldn't need to apply any significant pressure nor electrical contact during the soldering operation, and it would  need to be built only strong enough for alignment during heating.  It's just a gut feeling, but I think that would be a lot cheaper, way below 50 quid.

It's a good idea. In the past I've imagined a micro reflow oven, which would essentially just be some resistance wire in a very small (maybe 1 inch square) open-box enclosure (with ideally a viewing window too), that you could just temporarily place on top of an area of the PCB (i.e. open side facing down of course), just to solder QFN/BGA packages. But then I suppose it is similar to the handheld hot-air devices (which maybe are less gentle - I've never tried them for soldering).

A breakout board with built-in copper heating element sounds very cool though! Or, just brainstorming, maybe a sandwich board which has the element or resistance wire, that you clamp against the PCB (maybe screw holes to do the clamping) temporarily.

shabaz wrote:

 

But then I suppose it is similar to the handheld hot-air devices (which maybe are less gentle - I've never tried them for soldering).

I have hot air tools and it's certainly possible to use them for BGA & QFN. Hot air has it's challenges though, especially on a populated board. You have to mask off other components with kapton tape to prevent damage. Or in the case of small resistors and capacitors to prevent them getting blown away as they'll typically heat up much quicker than the bigger bga.

Other than initial reflow soldering, hot air is the way bga's, qfn's and even qfp's will be removed and replaced by the manufacturers. Although they probably will use a jig to hold the board level and hold the hot air tool above the board. Likely the board is heated from below too in order to reduce the thermal stress.

PoP could be rather challenging though and whatever the process there comes a point where it's uneconomical to do it by hand at all.

What we need are super-Peltiers, driven in one direction during installation to solder the BGA to the header, and driven in the opposite direction once in-circuit to pump heat from the BGA to a heat sink/spreader/pipe beneath.

I've heard of people converting toaster ovens into IR reflow ovens for SMT, for example this Ben Heck episode.  I haven't tried it myself -- there are plenty of dev boards available nowadays and thanks to RasPi and Open Source Hardware they're (mostly) pretty cheap.

Morgaine Dinova wrote:

 

In contrast, a breakout board or header with a built-in heater and solder pads wouldn't need to apply any significant pressure

actually, you don't want to apply any pressure, and as BGAs are self centering up to 50% off the pad (surface tension of the molten solder) all you need to do is give reasonable alignment guides for hand placement.

There's a host of other problems with reflow though.. are the parts moisture sensitive ?  did you bake them ?   heat from one side can give temperature gradients that cause the package or board to distort etc.  some of these things are why you see those interesting reflow temperature profiles in the datasheets

John Beetem wrote:

 

I've heard of people converting toaster ovens into IR reflow ovens for SMT

other than the "because I can" factor I've never seen the point.  Using reflow is simply the way to do it in quickly in a high volume manufacturing process.