Unleaded high temp solder in HORRIBLE - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 23, 2018, 01:55:59 pm
content: Just de-soldering a big heat sink with 5 diodes on it, must be the really high temp solder over 350C. My little 40W station can barely keep up at "400C" maxium, and the solder wick keeps getting stuck.I've added lots of 60/40 do dilute it, and remove it a bit at a time. I'm almost done.Not fun, now it start prying it out without breaking more traces

author: Brumby
author_rank: Unknown
timestamp: April 23, 2018, 02:00:19 pm
content: Doesn't need to be high temperature solder ... it can simply be heat loss through that big heatsink - and your 40W iron would be having a hard time of it. Just because you might have a temperature display for the iron that says 400ºC doesn't mean the solder joint is getting that hot at all.Adding extra solder could simply have provided better heat transfer between the iron and the joint. It is a common technique for all sorts of joint desoldering.

author: wraper
author_rank: Unknown
timestamp: April 23, 2018, 03:26:25 pm
content: Lead free solders used for electronics usually have melting point in 217-227oC range. 40W is quiet weak to desolder heatsinks. Keep in mind that what is shown on display in not nearly close to the actual temperature at solder joint, especially if you use sorts of hakko clones and tip not big enough.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: April 23, 2018, 04:54:23 pm
content: Get a pistol grip "old style" soldering iron. I use a 75 one to desolder surface-mount D2PAK, and it's actually a bit slow for that.

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 23, 2018, 05:56:32 pm
content: Yeah I have a 100W weller, but I got, and a lot easier/cleaner than the 1st 2 HSsinks

author: ejeffrey
author_rank: Super Contributor
timestamp: April 23, 2018, 10:58:30 pm
content: If you have any way to pre-heat the heat sink, such as with a hot plate, that will really help. If the bulk of the heat sink is at 100C it is a lot easier to heat the joint up to 220 C.

author: Brumby
author_rank: Unknown
timestamp: April 24, 2018, 12:58:06 am
content: If it were me, I'd be getting my hot air gun onto the heatsink.It's a simple technique that makes a HUGE difference.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: April 24, 2018, 06:52:21 am
content: BTW many temperature readouts do not accurately reflect the tip temperature when under thermal loading. They are only correct when the iron is idle. The newer types with the element and sensor built into the actual tip reduce this problem, but at the expense of, well, more expensive special tips.

author: ElektroQuark
author_rank: Unknown
timestamp: April 24, 2018, 07:00:39 am
content: Use a pan to preheat the heatsink.

author: KL27x
author_rank: Super Contributor
timestamp: April 24, 2018, 07:58:10 am
content: QuoteAre you 100% sure? I actually did a test and found the old school 888 with genuine 3mm bevel tip was measurably better in this aspect than two knockoff T12 stations with knockoff 3mm bevel tip. Of course that's not a fair comparison, but I was a bit surprised by the result. I thought the T12 should win by at least a little (even though 2 months of use made me feel like they were pretty much the same). So, even though they were knockoffs, it made me curious. I wondered if perhaps most of the temperature drop is going to happen somewhere between the sensor and where the tip gets skinny towards the tip and that the integrated sensor can't really get enough closer to matter. Yeah, there's less optimal connection between heater/sensor and the tip in the non-integrated tip, but it's like a huge area of transfer. Like using 4x the cross section of aluminum wire to conduct as well as copper. But maybe the slight advantage of the 888 was because the knockoff tip and station just stinks.Undisputedly, a major advantage of the integrated heater is getting the heat into the tip vs the handle. The T12 knockoff can do higher heatsinking higher duty cycle soldering for sustained periods without heating the handpiece as much.https://www.eevblog.com/forum/reviews/t12-clone-vs-888-practical-test-results/

author: Brumby
author_rank: Unknown
timestamp: April 24, 2018, 08:11:36 am
content: The closer to the joint you can get the temperature sensor, thelessthe problem. It can never be eliminated unless the sensor is actuallyonthe joint.Quote from: IanMacdonald on April 24, 2018, 06:52:21 amThe problemwillbereduced- it will not be eliminated.