On Mon, Jan 8, 2018 at 4:32 AM, Hrvoje Lasic lasich@gmail.com wrote:
did you ever think about in investing in small PNP machine (or just small oven plus some hand tools), like being able to produce small batch in house and test it qucikly?
No, this would be a horrible idea, I speak from experience here. If the end-product had a few parts (Arduino-ish, BOM < 30 parts), if the smallest passives were 0603's and if the smallest IC's were SSOP's, then yea it MIGHT be doable. But the EOMA68 board has BGA's and (I'm guessing) 0402's and likely some 0201's? The yield rate in a DIY situation would be prohibitive. It is actually cheaper to pay the labor rates and NRE's to a professional that has a process that's dialed in, and a line of machines that aren't toys.
do you have any idea how reliable www.openpnp.org project is currently, for example to meet your specs on board with soem available hardware?
I know the author of that program personally, I hired him and paid him to work on that program for a few months as we tried to make a small desktop machine that could do solder paste application and reflow in addition to pick and place.
OpenPnP works, but that's not the issue. Stencil printing issues and reflow issues would still make the yield horrible. Cheap manual stencil printers lead to issues like tombstoning. Cheap reflows don't get the heat even, which means that certain parts of the board don't get fully soldered. There's a reason that the professional machines are several meters long with various temperature zones and there's a reason that they take a bit of effort to setup correctly. Even if he got some surplus machinery and an area to set it up (including ducting for the exhaust and three-phase AC hookup), there's still the issue of nailing down the actual process, there's just so much to go wrong and that's why so many companies leave that sort of stuff to other companies that are better situated to deal with those kind of problems.
It's not exactly easy for me to say this either, because my dream was to make a machine for projects like EOMA68; to make the development cycle cheaper and quicker. I failed in that regard, and honestly nobody out there has really nailed it to the point where you could start churning out single board computers with BGA's an tiny parts and get close to 100% yields, in a DIY setup. It's sad but that's the reality that we live in.
For the record, while I vehemently disagree with LKCL on other matters like 3D printing and funding via bitcoin mining, I do completely agree with his decision to get a few boards produced and tested before doing a complete run. Even with all the review, there are still plenty of possibilities for show-stoppers.
The only suggestion that I would make -- and it's a big one -- is to send Mike (at the factory) a full test rig that is capable of verifying that an EOMA68 card works properly. This is an essential step of every production run, and I'm honestly surprised that in the update LKCL is planning on doing that himself. which pushes the schedule out to the right by another 3 days. This test rig would merely be a little board that the card plugs into, with HDMI monitor, keyboard, and some testing software to test the memory (Memtest86+), hard drive, peripherals, etc. Once production is going, the factory will need to be testing them anyway before they leave, this would be a good opportunity to test them, yet I saw nothing about that in any of the updates or email traffic. Even if this is something that LKCL personally does not have time to work on, surely someone in the forum could take on this task. So how were you planning on approaching the factory testing? If you've got it all figured out, then why isn't it going to be used for the next immediate run? And if you've not had time to get to it at all yet, why not let someone on the mailing list work on it? I can certainly give a lot of advice in this department. Hardware and software testing of embedded modules is not only what I do at my day job, I had a lot of experience while living in Shenzhen in how to make test fixtures for embedded products. I've got advice on how to make them bilingual so that they can actually be used in the factory by non-English speaking test technicians, and lots of other advice. Just let me know.