Soldering wick not absorbing

Deleted member 115935

Joined Dec 31, 1969
0
An off topic

I always get confused by heat and temperature !

but difference between heat and temperature..

De soldering needs big heat, but normal temperature to melt solder
 

MisterBill2

Joined Jan 23, 2018
13,707
For the solder removal process to work the solder braid must be hot enough to melt the solder and keep it melted as it flows away. THAT is how the process works.
And a response to post #60. Temperature is reported in degrees, heat is reported in calories or BTU s .Temperature iis the intensity , "heat" is the quantity.
 

narkeleptk

Joined Mar 11, 2019
548
I've applied flux on both sides and pressed it on soldered joints but the wick is not absorbing.

I'm doing this for the build it yourself RTL-SDR project, I need to remove the USB connector, IR sensor or LED and antenna connector from the dongle,
You can try one big glob of solder over all the joints of the component your trying to remove (use the large knife tip).
I do a lot of soic8 memory chips like this instead of hot air when they are directly beside bga chip's.
 

MisterBill2

Joined Jan 23, 2018
13,707
It's not the braid that heats the solder, it's the iron tip. The tip should never really touch the braid. Many so called specialists, the majority being on YT, show how tu use de-soldering wick between the tip and PCB but that's not the recommended way.
For the solder to flow into the solderwick the wick must not chill the solder and solidify it. THAT takes a quantity of heat. Some times that method may work, many times it would not work. I wonder where your information came from.
 

MisterBill2

Joined Jan 23, 2018
13,707
I have never had any problems doing it the way that I described. Also I have never had the luxury of multiple sizes on hand, nor such a nice applicator. In some instances it has been necessary to use a solder sucker to remove the solder from the braid so that the braid could be re-used. Freshly tinned solder braid works very well.
 

narkeleptk

Joined Mar 11, 2019
548
Why would someone want to use hot air to remove a SOIC8? There is way more convenient and safer ways to proceed. Pulling a SOIC8 should not take more than 5 seconds.
Whaaa? Hot air is amazing at removing smd components. You going to try and suggest Tweezers? No thanks.
 

narkeleptk

Joined Mar 11, 2019
548
Much too long and risks are higher unless you are talking about large BGA chips. You don't seem to like tweezers, bad experience?
There's nothing slow about using hot air unless you have your temp set too low which is probably higher chance to damage the surrounding area since you'll be spending too much time there.

You're talking about PCB rework, right?
Yes.


yea I don't care much for tweezers at all plus tweezers are not convenient for me personally. I would have to constantly swap tips or have more irons on the bench waiting to go (already have two irons on all day). Many of the the things I need to remove would not work with tweezers but hot air is alwys fast and efficient for removing the different things I need to do daily and work in conjunction with my irons well enough.

Cant say I have damaged anything with hot air that I cared about not damaging...... Well I take that back, I tend to get my fingers once in awhile on the nozzle.
 
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Thread Starter

bypassrestrictions

Joined Jun 1, 2021
107
Before I restart the de-soldering, should I increase the temperature to maximum of 450 C? Now the residue of solder is mostly in the holes of the USB connector, would the wick absorb it from there at that temperature, is there any risk of damage nearby components?
 

MisterBill2

Joined Jan 23, 2018
13,707
The problem is seldom with the temperature, unless it is too low. The problem is usually with the ability to rapidly transfer heat energy to the solder. That requires some mass of metal, copper is best, at the point of contact and so the very low mass tips are simply unable to provide the heat. Unsoldering is different from soldering, and with using solderwick it is even more different.

AND, using a much higher temperature certainly does risk damaging components and lifting PCB traces.
 

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
107
The problem is seldom with the temperature, unless it is too low. The problem is usually with the ability to rapidly transfer heat energy to the solder. That requires some mass of metal, copper is best, at the point of contact and so the very low mass tips are simply unable to provide the heat. Unsoldering is different from soldering, and with using solderwick it is even more different.

AND, using a much higher temperature certainly does risk damaging components and lifting PCB traces.
Is the one you are referring to shown in the below images?

41iD3eto3DL.jpg

312RllkZx+L.jpg
 

MisterBill2

Joined Jan 23, 2018
13,707
Possibly the tip identified as "900M-T-4C" is closest, but all of them seem much less than the one on my really cheap 40watt soldering pen.
Those are all quite good soldering tips, each suited for a particular soldering situation, and all seem designed to applyjust enough heat to produce a good connection. Removing solder with solderwick requires more heat, if one is to be able to heat both the joint and the mass of the solderwick.
Unfortunately indeed, keeping the cheap soldering pen heated all day will destroy the tip in just a few days. so switching it on only when needed is the best alternative, but it is less convenient. That is the trade-off.
 

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
107
Possibly the tip identified as "900M-T-4C" is closest, but all of them seem much less than the one on my really cheap 40watt soldering pen.
Those are all quite good soldering tips, each suited for a particular soldering situation, and all seem designed to applyjust enough heat to produce a good connection. Removing solder with solderwick requires more heat, if one is to be able to heat both the joint and the mass of the solderwick.
Unfortunately indeed, keeping the cheap soldering pen heated all day will destroy the tip in just a few days. so switching it on only when needed is the best alternative, but it is less convenient. That is the trade-off.
Does your 40W soldering pen have a tip with much larger point?

842°F! Simply get a good station. Wait! Get a de-soldering station.
What temperature should I use? Were you the one who said, it requires more temperature to melt?
 

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
107
The problem is seldom with the temperature, unless it is too low. The problem is usually with the ability to rapidly transfer heat energy to the solder. That requires some mass of metal, copper is best, at the point of contact and so the very low mass tips are simply unable to provide the heat. Unsoldering is different from soldering, and with using solderwick it is even more different.

AND, using a much higher temperature certainly does risk damaging components and lifting PCB traces.
Lets say when I'm soldering SMA, my soldering iron is at 200 F, if I spend around 5 minutes with the tip of the soldering on SMA connectors, can other components away from it be damaged with the heat transferring to them?
 

Ya’akov

Joined Jan 27, 2019
6,853
Lets say when I'm soldering SMA, my soldering iron is at 200 F, if I spend around 5 minutes with the tip of the soldering on SMA connectors, can other components away from it be damaged with the heat transferring to them?
A 200°F soldering iron won't even melt the solder. Eutectic alloy lead/tin solder, which has the lowest melting point, melts at 361.4°F. 200°F would not solder anything, but it also probably wouldn't harm any components except possible low grade switches and cheap plastics.
 

Thread Starter

bypassrestrictions

Joined Jun 1, 2021
107
A 200°F soldering iron won't even melt the solder. Eutectic alloy lead/tin solder, which has the lowest melting point, melts at 361.4°F. 200°F would not solder anything, but it also probably wouldn't harm any components except possible low grade switches and cheap plastics.
I meant to say 200 C by mistake I typed F. When I set the repaired soldering iron to 200 C, after sometime checked it's temperature with an infrared thermometer and it showed 167. F and it was able to melt the solder and it remained on connector for few minutes and other parts of the PCB also got hot, I'm wondering if it could have damaged anything?
 

Ya’akov

Joined Jan 27, 2019
6,853
I meant to say 200 C by mistake I typed F. When I set the repaired soldering iron to 200 C, after sometime checked it's temperature with an infrared thermometer and it showed 167. F and it was able to melt the solder and it remained on connector for few minutes and other parts of the PCB also got hot, I'm wondering if it could have damaged anything?
First, IR thermometers will not give reliable readings from reflective surfaces. To measure the tip temperature of an iron, you need a purpose built thermometer like the Hakko 191 that uses a specialized thermocouple designed not to be contaminated by the solder alloy.

Second, you should never have an iron in contact with the work continuously for "a few minutes". The proper time for soldering and desoldering in 2-3s. If you can't transfer enough heat in that time, you are using the wrong iron and you are definitely at risk of damaging the board and components by overheating.

The iron/tip must have sufficient thermal mass to heat the joint to the melting point of the solder in those 2-3 seconds. If not, it is too small.
 
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