#qi-hardware IRC log for Friday, 2012-07-13

qi-bot[commit] Xiangfu: debian: update debian version (master) http://qi-hw.com/p/fped/6e61ff902:02
qi-bot[commit] Xiangfu: naonote-files: add missing file: sysctl.conf (master) http://qi-hw.com/p/openwrt-packages/be0ae2602:32
he2does anyone want to buy my nanonote 09:30
he2i have no time to use it and i would like to give it to someone who has more time and fun with it09:31
kuribashellekin: how much?10:28
kuribasI meant he2...10:28
kyakit would be funny to sell for 130 USD, which is bigger than the original price but still smaller than the current price :)11:30
wpwrakbuy low, sell high ;-)12:02
larschm, maybe wolfgang should have annouced the price change two weeks before it was done. Maybe somebody would have bough the whole stock in the hopes of being able to sell it later at a higher price12:05
wpwrakthat's an interesting idea ;-)12:26
wpwrakof course, anyone who buys the whole stock can set any price they want ...12:26
larscwell, the current stock12:40
wpwrakmay be hard to make more at the present time. after all, it's been several years since the last run. eventually, that fab will throw away their old stock of parts, tools, and such.12:50
larscI still remember as if it was yesterday when I had my first nanonote prototype on my desk13:06
wpwrakyour firstborn :)13:31
wpwrakhmm. i wonder what the general rule of thumb is when it comes to solder paste and through-hole components. is solder paste commonly applied to the copper rings around holes ? never ? sometimes ?17:40
kristianpaulafter trial and error ;)18:20
wpwrakhmm :) what determines the decision ?18:51
kristianpaultime for the estaño/solder to stick on the pad? also shape and brighness19:00
kristianpaulwhen aplying heat^19:01
wpwrakhmm ..19:11
DocScrutinizer05wpwrak: basically thru-hole isn't meant for reflow ;-)20:02
DocScrutinizer05SMT and thru-hole are incompatible technologies. Starting with foamwave-solder-bath vs reflow20:05
wpwrakwhat if you have a board that has both types of components ? would you apply solder paste to the copper of through-hole components ? never ? don't care ? always ?20:05
wpwraki wonder how they do it in real life. applying solder paste may be quite hard if you have TH components on the board, so you'd probably always do SMT first20:06
DocScrutinizer05I'd maybe try to apply lots20:07
wpwrakbut then, how do you solder the TH components ? maybe manually ?20:07
DocScrutinizer05I guess usually manually20:07
wpwrake.g., milkymist has a ton of through-hole connectors20:07
wpwrak(lots) ... of solder paste ?20:07
DocScrutinizer05hoping for it to flow 'into' the hole20:08
wpwrakhmm. not sure if this works. already your stencil should have just one thickness20:08
DocScrutinizer05actually you'd need so much that it covers the hole, and you stick the TH-wire of component thru it20:09
wpwrakyeah :)20:09
wpwrakdoesn't sound like the normal way of applying solder paste :)20:09
DocScrutinizer05it's incompatible 20:09
wpwrakbut i wonder if there may be other reasons for putting solder paste on the TH copper rings20:09
DocScrutinizer05easier soldering afterwords20:10
wpwrakyup, along these lines20:10
wpwrakalso, i could imagine that some types of surface finish don't survive SMT. so solder paste could then replace them. e.g., those inexpensive "organic" finishes.20:11
wpwrakotherwise, you'd have to apply a more durable finish, which could mean considerably higher cost (e.g., if this would be the only place where you need it)20:11
wpwrakbut all this are just wild guesses20:13
rohwpwrak: afaik you do smt mounting first, and then do the through-hole in a wave-soldering machine20:19
DocScrutinizer05on singlesided SMT that may work20:20
DocScrutinizer05since soldering sides of SMT and TH components on same side are actually opposite20:21
DocScrutinizer05don't forget the "ancient" names "component side" and "soldering side"20:22
rohwpwrak: http://sr-systems.de/content.php?show=PCB&lng=deu&style=std right side pictures, last few20:23
rohDocScrutinizer05: afaik you protect smt parts with kapton tape from the wave if you have doublesided20:24
DocScrutinizer05I wouldn't argue20:24
DocScrutinizer05though you should make damn sure then taht the solder wave doesn't deposit solder under the kapton on the corners20:26
DocScrutinizer05actually I guess it's an evaluation of manpower costs for manual soldering vs material for wave-soldering20:27
wpwrakroh: and do you solder paste the copper around TH holes ? always ? never ? don't care ? it depends ?20:28
DocScrutinizer05wpwrak: basically there is no such thing as "copper around TH holes" on SMT side20:30
wpwrakif we assume a double-sided board, you'd have SMT on both sides20:31
DocScrutinizer05s.SMT side.component side.20:31
wpwrakso would you deposit solder paste on the TH copper ?20:31
wpwrak(comp side) i mean SMT components on both sides20:31
rohwpwrak: dunno20:31
wpwrakDocScrutinizer: and why would you deposit solder paste on the TH copper ?20:32
DocScrutinizer05the wave-solder machine will thank it20:32
wpwrakheh :)20:32
DocScrutinizer05better solder than anything else on the copper20:33
DocScrutinizer05since anything else is $dirt20:34
wpwrakwell, could be bare gold20:34
DocScrutinizer05you would place gold on solder pads? :-O20:35
DocScrutinizer05dang you must be rich20:35
wpwrakyou basically have four choices: naked copper (not a happy choice for sure), some not very durable finish, a durable finish, and your regular finish, plus solder paste20:36
rohafaik usually one does it either like in the photos i pasted the url to, or for lower volumes: manually.20:36
rohso.. smt automatic placement and soldering, and add the through-holes by hand.20:36
wpwrakDocScrutinizer: seems to be pretty common. and doesn't seem to affect the price a lot.20:36
DocScrutinizer05yep, and solderpaste on ds-pcb for the TH-pads is nothing bad 20:37
DocScrutinizer05hmm, even gold doesn't mind a solder layer on it20:37
DocScrutinizer05solder gets liquid in wave-solder-engine and you get best possible solder-joint20:38
DocScrutinizer05and for 'connecting' the solder to gold, solderpaste is no worse than wave-solder20:38
wpwrakif someone didn't put solder paste there (and assuming you had a decent finish, so you won't have a layer of coper oxide to worry about), would you consider this a bug ?20:40
rohi actually prefer gold on all mechanical througholes and no solder if its not a joint. so even dnp-part-pads shouldnt have solder.20:41
rohon the mechanicals solder is a problem because its modifies the thickness of material, its not really 'even' and dia of throughholes are off20:42
DocScrutinizer05solder(-paste) *only* where components will be 30 min later20:42
DocScrutinizer05and for goldplated pads it's arguable20:43
rohhow were the mm1 rc3 made?20:43
rohi guess manual throughhole soldering?20:43
wpwrakDocScrutinizer: you expect chemical deterioration of the solder if left in the air for too long ? (it'll have been heated, so it's no longer solder paste)20:44
wpwrakroh: manual seems likely20:44
DocScrutinizer05heard of jolla? Wonder if they will consider my application20:46
DocScrutinizer05anyway, time for dinner & booze20:46
Aylaguys, is the "cache" instruction present on the jz4740? I'm getting an "illegal instruction" here22:45
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