Soldering and desoldering components, does it damage it & Thermal paste question

[canidoit]

I would like to know from experienced builders what the rule or usual outcome is regarding soldering and desoldering components before it becomes damaged. Are components made to withstand soldering iron heat alot which I have set to 360 degrees on my iron.

Thermal paste, do they become glue like when used? I am contemplating using thermal paste for one of my builds for a heatsink to a 2N3055G but I need the heatsink to be easily removed in the future for troubleshooting or mods?

 

[pucho812]

thermal paste does not act in any way shape or form like  glue...  as for soldering and de-soldering parts, parts will usually withstand the stress of soldering without issue. When it comes to de-soldering you have to be careful as you can pull traces or destrop the solder pad and such. Parts are usually designed to be removed but be gentle. Like anything else prolong exposure to heat is a no no. If you plan to de-solder parts get yourself a de-soldering vacuum, makes repairs a breeze.

 

[Sredna]

What pucho wrote...

Greatly depends on the component and especially the time of heat exposure.
Normally components withstand soldering tempratures for a couple of seconds,
to be on the safe side you could use a clip to protect the component.

Normal heat paste does not stick like glue, and remember to not use too much.
A thin layer is sufficient.

 

[JohnRoberts]

Back in the not so good old days parts were more sensitive to soldering temperature, but modern parts are pretty robust. While hard to kill I guess it is possible, but many are designed to spend several seconds sitting in a pool of molten solder in a wave soldering machine.

The only modern parts I've had temperature trouble with (not counting PCBs  ) was some SMT film capacitors that came back from the contract mfr with some open circuit and a bunch of major tolerance shifts...  I changed to more robust NPO ceramic parts and didn't have any more problems.

re: heatsink thermal compound. Yes, it is not glue. There are some specialty thermal epoxies but they are a different product.

Regarding thickness.. the main function of heat sink grease is to fill the tiny air gaps between less than perfectly flat surfaces. You don't need more than a thin layer of compound with reasonably flat parts. Too much compound could hurt the heat flow. The grease is better than air but not better than metal.

JR

 

[Stagefright13]

I remember soldering a bunch of transistor in wrong back in the '80s. Just said E B C no other silkscreen and no internet for datasheet. By time I got those buggers out the leads looked like Jagged lightning bolts. Plus they were run backwards while I stupidly plundered on. As far as I know there was no Mouser back then. And NO I didn't have 50 of them. Just the ones with the kit. I straightened the leads and that oscillator actually worked! I was amazed. I have always had faith in transistors after that.

Not to say you can't destroy them! I got them out without solder wick Or a sucker.

I used to solder SMD components back in the day by hand for a military contractor with silver solder and flux. But I never saw the board after that......

The regular heat sink grease like you get at radio shack doesn't turn to glue. But Artic silver at least the older versions can be hard to remove after dozens of heating's. And it takes just a very thin film spread with a credit card. Even with artic silver you can break the bond carefully with a razor. No biggy.

John

 

[Stagefright13]

Canidoit use thermal paste if ya got it. I just saw your thread. Just takes a thin film you be ok!

John

 

[Dark1]

When I desolder almost anything (using a desoldering station, saves so much time and hassle!), I usually use alligator clips to sink the heat off of components. There are also special heatsink clips made of copper created exactly for this purpose, but I have not found them for sale in Europe (at least not in usual stores like RS Components).

Hope this helps!
Lukas

 

[haima]

whenever someone mentions de-soldering i am compelled to mention the hakko 808 - it's one of those things that i don't know how i lived without for so long! a real pleasure to use, and easy to clean. i got it pretty cheap on ebay, new with a kit of spare parts.

i'm sure the big de-soldering stations are even better - but for the diy guy (and many pros too) this unit is a winner i think.

as you were... 8)

 

[JohnRoberts]

Indeed polystyrene, mostly obsolete now, never were very robust or production friendly. You will notice they usually come with tiny lead wires, pretty much to not conduct too much heat to the low temp plastic body. I have even had problems with polystyrene caps corrupted by water cleaning with pressurized air drying.

JR

 

[pucho812]

I just realized I said desolder vacuum. I wanted to say desoldering station.

Like this one below

do not use these as they can cause more damage then good.

 

[thefastvinny]

If you can't afford a desolder station, (or just don't have a demand large enough for spending that kind of money) Iron temperature will largely affect the outcome. I have found out by destroying traces in the past that too low of temperature will actually burn the PCB and damage traces because it is not hot enough to effectively melt all of the solder so the component can be lifted. Lower temps take longer to melt solder and in tern will heat up everything else around it more. If you have to resort to using solder wick, I would spend some time practicing with it on something that isn't going to cost you if it burns up. The less time with the iron on the components the better. For older units that haven't been heated up in a while, they can be more difficult to work with. Try tinning the contacts before removing them.

Bottom line, a good desolder station is the way to go. Saves soooooooo much time. And like Pucho said, forget about the mechanical, spring-loaded solder suckers.

 

[Stagefright13]

LOL Pucho I have that blue one. It "sucks" I always use solder wick. Works better. But like fastvinny said old solder joints are a nightmare.

Don't think I have built anything without some solderwick.

John

 

[jwhmca]

Cheers to the Peeps that made the compact desoldering stations/electronic pumps... I LOVE my Denon SC-7000z

I use wick on occasion and have learned a few tricks with it.

1. Don't touch it too much. Seems like the oil from your hand inhibits the wicking action.
2. Re-solder a tough joint before you try to wick it. Those NASTY Grommets, baked solder... Or what about the Lovely CAP Pee damaged solder... Those are almost impossible without a vacuum.
3. Don't "Dig&Twist" that will "Burn & Lift" your trace. Fresh solder, place the wick so you can "Pull" it through the heat of the iron.  

 

[Dark1]

>>Re-solder a tough joint before you try to wick it.

That applies to de-soldering with de-soldering stations etc. as well - applying fresh solder [first] to the old joints that do not want to melt usually solves the problem...

 

[thefastvinny]

Posted by: jwhmca
"Or what about the Lovely CAP Pee damaged solder"

Haven't heard that one before. Nice

 

[JohnRoberts]

>>Re-solder a tough joint before you try to wick it.

That applies to de-soldering with de-soldering stations etc. as well - applying fresh solder [first] to the old joints that do not want to melt usually solves the problem...

The mechanism associated with applying fresh solder is basically the flux in the solder. You can buy flux by itself. I got some liquid flux in a pen dispenser from DIGIKEY.

JR

 

[bobschwenkler]

do not use these as they can cause more damage then good.

What's the reason or experience behind this statement? Is it in regards to pulling solder pads off PCBs or something else?

 

[pucho812]

do not use these as they can cause more damage then good.

What's the reason or experience behind this statement? Is it in regards to pulling solder pads off PCBs or something else?

yes they can cause that kind of damage...

 

[mnats]

As a full-time repair monkey, I've never had a problem with those mechanical vacuum devices even on delicate boards. So much of using tools boils down to acquired skill and technique - not to say that some expensive powered devices can't make your life easier.

Having said that none of those devices are much good if you're removing a 100+ pin surface mount monster. I've had good results using a hot air tool with ICs unless they've glued the component onto the board.

Applying new solder in the modern age also has to do with lowering the melting temperature and viscosity by adding some good old fashioned lead to that RoHS lead-free crap. Recently I picked up some Tix solder which can stay molten longer at a lower temperature (275F or 135C) giving you enough time to heat each side of a large multi-pin component with a regular soldering iron until you can just nudge it off the board.

 

[bobschwenkler]

How does a desoldering station work? I've never encountered one in the real world and it's hard to tell from photos what's going on.