#garfield Logs

Nov 22 2024

09:55 AM aandrew: what's hard about soldering PLCCs? put solder on ONE pad on the PCB, tack down the PLCC and align it, let it cool, then tack down one pin/pad on an opposite corner. check and double check alignment, then you can either rake solder each side or do pins individually. I find PLCCs are a little too wide-pitched to rake solder well but YMMV
10:10 AM aandrew: so how do you re-use OTP 8051s? Do they have a "run from external memory" mode?
10:19 AM polprog: rue_mohr: yep i got it
10:19 AM polprog: i was planning to do the PLCC and other SMDs on the top layer with solder paste and hotplate
10:19 AM polprog: i didnt get around to moddig that oven after all
10:19 AM polprog: also, reminds me i was to get an electric hob for the chemistry
10:20 AM polprog: the oxidizer droplets attack the steel surface of the hotplate very badly
03:18 PM polprog: well i got the ferric chloride rite of passage done
03:19 PM polprog: etched one of the enig-coated PCBs to get the clean material
03:19 PM polprog: the other one didnt want to
03:19 PM polprog: is ferric very sensitive to water hardness?
03:19 PM polprog: do you use distilled water for etching?
03:22 PM Tom_L: persulphate doesn't make quite the mess
03:24 PM Tom_L: ammonium persulfate or sodium persulfate, one works better and i can't remember which one
03:24 PM Tom_L: http://tom-itx.no-ip.biz:443/~webpage/etching/etch_index.php
03:24 PM Tom_L: works better warm
03:28 PM Tom_L: if you just want to clean it, get some copper pan cleaner from the store
03:31 PM polprog: agreed - sodium persulfate is used here
03:31 PM polprog: however it does not want to etch away enig
03:32 PM polprog: i have some enig coated PCBs and i need to get rid of the metal to leave a clean substrate for my thesis experiments
03:32 PM polprog: copper I cleaned with persulfate, that went a-ok
03:32 PM polprog: ENIG was cleaned with iodine pretty well, but today I tried doing it with ferric and it didnt go very well
03:33 PM polprog: maybe i used not enough, the first PCB went allright
03:33 PM polprog: took 30 mins but the solution was cold
03:33 PM polprog: then the second barely got etched, but in the meantime i noticed some tap water got into the beaker
03:34 PM polprog: and then it didnt want to be etched by the same iodine solution that etched in a few seconds two weeks ago
03:34 PM polprog: i need to redo the solution using clean glassware
03:34 PM polprog: did i post this here? https://polprog.net/rozne1/ircjunk/various/chem/kietch/iodine-iodide.html
04:25 PM Tom_L: i don't remember
04:25 PM Tom_L: i didn't see it
05:34 PM polprog: well there it is :p
06:13 PM rue_mohr: aandrew, yes, external mode
06:15 PM rue_mohr: polprog, always heat etchant
06:15 PM rue_mohr: aandrew, the angle of the pins is a snot with the PLCCs