#qi-hardware IRC log for Wednesday, 2012-10-17

pabs3anyone in Toronto? http://moxielogic.org/blog/?p=67000:04
hellekinwpwrak: we need to talk. Can we meet soon somewhere? I want to discuss DRM with you and Thiago01:01
wpwrakhellekin: something to discuss over some beers thursday evening ?03:00
xiangfukristianpaul, http://www.openmobilefree.net/wp-content/uploads/2012/10/IMG_1345.jpg . some experience on photo-paper-pcb.10:46
wpwrakxiangfu: did you scrub the pcb with steel wool and then clean it with alcohol before the toner transfer ?11:27
xiangfuwpwrak, only wool. (no steel wool, no alcohol) 11:28
xiangfuuse only wool do some clean.11:28
wpwrakxiangfu: you also don't seem to have sufficient clearance between traces and some bga pads. so unless you expect them to connect or you don't care, you should move the trace exactly in the middle between the pads11:28
xiangfuyes. I am still improving the design now. 11:29
wpwrakyou'll need the steel wool. first, it removes oxides, which other methods can't touch. second, it leaves small scratches that improve adhesion11:29
xiangfugot it. thanks11:29
xiangfuwpwrak,  now I understand more on pcbnew. I have a question on those layers btw. 11:30
wpwrakand after the steel wool, you need alcohol to 1) remove the dust/dirt left behind by the steel wool, 2) remove any grease11:30
xiangfuok.11:30
wpwrakthe steel wool should be the fine type, with the steel about at thick as human hair. not the more coarse steel wool where the steel is about 1 mm (for scrubbing pots and such)11:31
wpwrakwhat's the trouble with the layers ?11:31
kristianpaulindeed clean is  must11:32
xiangfu(with the steel about at thick as human hair.) got it.11:32
xiangfuthe layer.. there are so many layers. like adhes, soldp, silks, mask, eco1/2, 11:32
xiangfuwhat are those layers for. is there any document about them?11:33
wpwraksoldp is for solder paste. that's used when you do the smt at a fab.11:33
xiangfuI understand the 'comments' layer. which is print after solder mask.11:33
wpwrakadhes is adhesive, also used at the fab (for items that need to be glued to the board, e.g., if they're on the bottom side and would fall off during soldering)11:34
wpwrakmask is the solder mask. that's a protective layer applied on top of the copper when making the pcb (at a pcb fab)11:34
wpwraksilks is the silk screen, the white printing you get on top of the pcb (at a pcb fab)11:35
wpwraknone of these usually matter if you make the pcb at home, but solder mask and silk screen must be correct if you have the pcb made at a fab11:35
wpwraknot sure what eco1/2 stand for. i don't use them. i think they're basically for some sort of comment.11:36
wpwrakthen you have "drawings" and "comments". one goes to the silk screen, the other is for things you use during design but that don't correspond to any structures on the physical pcb11:38
xiangfuok. drawings goes to silk screen.11:40
wpwrakin the sense that things you draw on "drawings" are automatically propagated to the silk screen. you could also draw directly on the silk screen, though. using the "drawings" layer makes it easier to hide your drawings, when the pcb gets crowded and you want to display only the things you're working on at the time.11:43
xiangfuok. I understand the adhes, mask now.11:43
xiangfuyou just answer what I want ask. (can you read my mind?. that is scare :)11:43
wpwrakheh :) is noticed that my explanation was ambiguous11:44
xiangfuwhat is the soldp for? like some pad have tin, and some not? right?11:44
wpwraksolder paste is a cream that contains solder (tin)11:47
wpwrakat an smt fab, it is applied on top of smt pads before placing the components11:48
wpwrakthen, when the pcb is put into the oven, the volatiles in the solder paste evaporate and the tin melts, making the solder bonds11:49
xiangfuyes. understand now.11:49
wpwrakyou sometimes also use solder paste for manual smt, but most things can be done without it (it's a bit messy to handle manually)11:49
wpwrake.g., it's useful for soldering crystals. not sure if you need it for bga, too. i never tried to hand-solder bga.11:50
xiangfuok.12:04
xiangfuI will try hand-solder bga without solder paste this week. :)12:11
xiangfuI already have 5 slx9-ftg256 chips on my desk.12:11
qi-botThe build was successful: http://fidelio.qi-hardware.com/~xiangfu/build-nanonote/openwrt-xburst.minimal-20121016-0538 13:30
qi-bot[commit] Paul Cercueil: Removed unused class variable 'useRamTimings' from LinkApp (packages) http://qi-hw.com/p/gmenu2x/c1a95a221:46
qi-bot[commit] Paul Cercueil: Add "editable" parameter: when "false", the link can't be modified. (packages) http://qi-hw.com/p/gmenu2x/170a7dc21:46
qi-bot[commit] Paul Cercueil: Dingux: set all the system links (except Terminal) as non-editable (packages) http://qi-hw.com/p/gmenu2x/79ea23421:46
qi-bot[commit] Paul Cercueil: Fix icon not appearing on loading menu of OPK packages based links (packages) http://qi-hw.com/p/gmenu2x/0ddc56221:46
qi-bot[commit] Paul Cercueil: Update "exec" to aim the binary if a change of directory if needed (packages) http://qi-hw.com/p/gmenu2x/6a9f42921:46
--- Thu Oct 18 201200:00

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