#homecmos IRC log for Wednesday, 2013-05-29

--- Wed May 29 201300:00
berndjanyone used magic(1)? i'm struggling with making labels05:16
berndjazonenberg: you have been summoned in #geda on OFTC; people want to know about your BGA process17:02
berndjwhat pitch do you manage to do?17:03
azonenbergberndj: I have perfect yield so far on 1mm (seven boards with a single FTG256 part on each)19:29
azonenbergas well as 1/3 on 0.5mm (three boards with a CPG56 part on each)19:29
azonenbergbear in mind, the 0.5mm parts were my first BGAs ever19:29
azonenbergand failed due to misalignment, not shorting etc19:30
azonenbergso i could probably do better now19:30
berndjheh, we were wondering about 0.5mm19:30
azonenbergIt's doable19:30
azonenbergI do not suggest it as a first chip, though19:30
azonenbergqualify the process with 1mm19:30
azonenbergthen do 0.819:30
azonenbergthen move down19:30
azonenbergThe bigger problem with 0.5mm is that you need microvias or super-tiny traces to break it out unless it's like CPG56 (two concentric rings with routing space between them)19:30
berndj1/3 of all chips or 1/3 of all balls?19:31
azonenberg0.8 and above you can do standard dogbone19:31
azonenbergI did three chips19:31
azonenbergOne worked19:31
berndjheh. cool19:31
azonenbergThe other two were so misaligned that the balls werent even touching the pads19:31
azonenbergi just melted holes in the soldermask19:31
azonenbergBut like i said, they were my first bgas ever19:31
azonenbergi didnt really know what i was doing19:31
azonenbergKnowing what i do now, i'm pretty sure i could make it work19:32
berndjwhoah, you tried them before you did the coarser-pitched ones?19:32
azonenbergthey were the cheapest bgas i could find19:32
azonenbergcoolrunner-ii CPLDs19:32
azonenberg$1.20 or so per chip19:33
azonenbergwhereas the cheapest FTG256 i could find was a spartan3a for $10ish19:33
berndjyou're nuts man!19:33
azonenbergYou're talking to the guy who did 01005s at home19:33
berndji know!19:33
azonenberg(and who thought that wasn't small enough, and wants to do an ASIC now)19:33
berndjaren't 01005s kinda hard to see with the naked eye?19:33
berndjwhat's your asic roadmap btw - DIY process or MOSIS?19:34
azonenbergthats a DIP14 for scale19:34
azonenbergI want to dual-track19:34
azonenbergin-house process to make some 74xx chips etc for the 1337 points and educational value19:34
azonenbergthen a mosis chip fast enough to actually compete with fpga-based stuff19:34
azonenbergi'll learn a lot more from making my own process, i'm sure19:35
berndjerr, is your DIP-sized board stuffed or is it empty?19:35
azonenbergThe second column is loaded19:35
berndjsecond row from left looks like it's been worked on, but i can't see the dust grains19:35
azonenbergi wasnt using a stencil so the paste is a little bit messy19:35
azonenbergThere's a better view post-reflow19:35
azonenbergThis is my old tweezers, lol19:36
azonenbergon 0.5mm QFP footprint for scale19:36
berndjthis is just soldering on boards you got made, not DIY boards too?19:36
azonenbergi got new tweezers just for 01005s http://1.bp.blogspot.com/-kBZPenm0cPA/T99wgnyWWuI/AAAAAAAAAIg/oqYNUxCN20A/s1600/S7302741_annotated.jpg19:36
Sync_ah 01005 tends to get annoying with your regular soldering iron19:36
azonenbergThere's no reason to maky my own boards19:36
azonenbergoshpark is cheap, better quality, and fast turnaround19:36
azonenbergthe reason to make an asic is different19:36
azonenbergmosis is expensive and slow19:37
Sync_I had to rework some boards that had a few misplaced components19:37
azonenbergSync_: lol19:37
Sync_but it's possible but no fun19:38
berndjbypassing mosis would be more expensive and slower still?19:38
berndjor do you have access to a school fab?19:38
Sync_but bga at home is no big deal19:38
azonenbergberndj: I meant, home fab19:38
azonenbergYou'd get faster turn times for sure19:38
azonenbergbut the main reason is still education19:38
berndjyeah, we're waiting for you to liberate the world with a home fab process19:38
Sync_it's handy to have a laser reballer if you get it wrong19:38
--- Thu May 30 201300:00

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