Any tips/advice for hand soldering TSOT23-6? - Page 1
Forum section: electronics / general

author: bsodmike
author_rank: Regular Contributor
timestamp: November 05, 2020, 01:07:29 pm
content: Hi all,I have an old Metcal MX-500 station and used my finest chisel tip on an IC adapter board. Here's the IC in question:https://export.farnell.com/linear-technology/lt6654ais6-1-25-trmpbf/voltage-ref-series-1-25v-tsot23/dp/2761954Adapter board:https://export.farnell.com/roth-elektronik/re910pin/pcb-ic-adapter-6-sot-23-7-62mm/dp/3050943?ost=3050943The issue I faced is that the pads on the adapter board are very close, so my usual trick of applying solder and wicking across didn't work as much as I liked.Looking at the datasheet (attached), the failure here really was the adapter PCBOh well, I'm now ordering this from ARIES and hopefully it'll work better.https://export.farnell.com/aries/lcqt-sot23-6/ic-adaptor-6-sot23-to-dip-2-54mm/dp/2476032?ost=2476032

author: ebastler
author_rank: Super Contributor
timestamp: November 05, 2020, 03:14:29 pm
content: Not sure I understand the specific difficulty there. In my experience, SOT pads are large enough to touch them with a soldering iron and a bit of solder, one by one? Only on the first pad, I pre-tin the pad and then tack on the part by touching it with the iron.Youtube has plenty of tutorials:https://www.youtube.com/results?search_query=solder+sot-23

author: Howardlong
author_rank: Super Contributor
timestamp: November 05, 2020, 03:30:21 pm
content: I'm not clear what the particular problem is either.Do you use magnification? You should.Are your hands a bit shaky? Lay off the caffeine! I also find that first thing in the morning I'm a bit shakier than later on in the day.o You should be able to easily do one pin at a time without resorting to wick.o I use a flux pen on the pads.o Tin a corner pad.o Position & hold the device down with tweezers, & apply heat to the pin on the pad you just tinned, maintaining the correct device position with the tweezers.o Solder the remaining pins.

author: tooki
author_rank: Super Contributor
timestamp: November 05, 2020, 04:29:50 pm
content: Also, add flux. It’ll help prevent bridging.

author: ebastler
author_rank: Super Contributor
timestamp: November 05, 2020, 05:18:38 pm
content: One more thought: Make sure your solder wire is not too thick, so you can dose it properly. I like 0.5 mm.

author: georges80
author_rank: Frequent Contributor
timestamp: November 06, 2020, 01:56:21 am
content: Using a tiny tip is counter productive to soldering something relatively large such as a sot23-6. I would use a something in the 0.7 to 1mm width chisel tip, some decent solder and a dab of liquid flux. Job done in a few seconds.cheers,george.

author: ebastler
author_rank: Super Contributor
timestamp: November 06, 2020, 05:58:31 am
content: Quote from: georges80 on November 06, 2020, 01:56:21 amIf you were referring to my prior post -- I was not talking about the iron's tip, but about the solder wire. OP had mentioned the need to use wick, which makes we wonder whether he is using thick solder wire, resulting in too much solder being applied.

author: bsodmike
author_rank: Regular Contributor
timestamp: November 06, 2020, 07:36:39 am
content: Thanks to all - My approach isn't very different to what most here have recommended. My process is:Apply fluxTin the padAttempt to tack on one legGo leg by legI'm using this 0.5mm lead free solder:https://export.farnell.com/multicore-loctite/96sc-400-5c-0-50mm/solder-wire-lead-free-0-5mm-250g/dp/1115458I had better luck with my 1.7mm chisel, but a 1mm chisel would be helpful - thanks for the suggestion! With regards to my previous attempts, when I got back to my bench later it seems one had survived. The 1.25Vref has been pretty solid. Accurate to 1.2500 or 1.2499 (depending on temp change in my lab area).

author: bsodmike
author_rank: Regular Contributor
timestamp: November 06, 2020, 07:38:37 am
content: caffeine!! Hah, thanks for the heads up. Never thought of that...

author: thinkfat
author_rank: Unknown
timestamp: November 06, 2020, 09:09:53 am
content: Looking at that picture, too little flux.

author: Howardlong
author_rank: Super Contributor
timestamp: November 06, 2020, 11:37:13 am
content: Quote from: thinkfat on November 06, 2020, 09:09:53 amCertainly looks that way. Either the flux has burned/evaporated away, or there wasn't much before hand.You don't need Louis' levels of flux for this, I just use a flux pen on the board.I'm wondering if the OP keeps re-applying heat multiple times? Maybe because the iron's not hot enough?Just a short dab for a second or so with the iron should be enough for the anchor pad.Then a short dab with solder for the remaining pins. Don't apply solder to the tip, heat up the pad and pin for a second, and apply solder to the joint. Shouldn't take any more than a second or two total each joint. Clean your tip regularly in a wet sponge and/or that brass coily stuff. If there's any residual solder on the tip, the flux will have burned away, so get rid of it. Similarly, if you keep going back in on a joint, the flux will disappear. The joints should look smooth, not like an unsurfaced road ;-)FWIW I use 350C to a 0.2mm conical, although I know there's a school of thought that prefers a chisel tip.

author: Refrigerator
author_rank: Super Contributor
timestamp: November 06, 2020, 06:09:01 pm
content: In my experience there's no need for any special preparation, tip size or solder thickness.I personally just put some flux around the IC and a dab of solder on my soldering iron tip (3mm chisel tip), then i just touch the pads and it's soldered.Never had problems with bridging.