Soldering question

[jeff6666p]

I'm trying to change a capacitor on my motherboard because it is leaking. Now one of the pins seem to be stuck in the hole still and I cant get it out. I have been trying for the last 40 minutes with no luck. How do I get this pin out?

[mariushm]

Re: Soldering question

Usually by heating up the motherboard with some hot air gun, then adding some solder to that area and then using a stainless steel needle or dental pick to push out the lead while the solder is liquid (solder doesn't stick to stainless steel).

[larrymoencurly]

Re: Soldering question

I'd chop the capacitor off on the top side so the pins can be separated from one another and the stubborn pin gently and carefully pulled out after blobbing some more solder over its hole.

How many watts is your soldering iron, and how clean and how well tinned is the tip? I once had a 40W iron with such a dirty tip that solder wouldn't melt even when pressed directly against it. Also I've had worse luck cleaning tips with a damp sponge than with a damp cloth or paper towel or that curly hair brass, copper, or stainless steel.

[jeff6666p]

Re: Soldering question

I'd chop the capacitor off on the top side so the pins can be separated from one another and the stubborn pin gently and carefully pulled out after blobbing some more solder over its hole.

How many watts is your soldering iron, and how clean and how well tinned is the tip? I once had a 40W iron with such a dirty tip that solder wouldn't melt even when pressed directly against it. Also I've had worse luck cleaning tips with a damp sponge than with a damp cloth or paper towel or that curly hair brass, copper, or stainless steel.

The capacitor is already off, it's just a small piece thats stuck. I have a 25w iron that's brand new. it melts solder no problems but I just can't seem to get the piece out. I haven't tried a pump yet I'm waiting for it to come in. Would using a de-solder pump get it out? I've tried using the point of a fine nail to push it out but it didn't.

[mariushm]

Re: Soldering question

25w is too low for motherboards.

Motherboards are made out of several layers with thick ground traces that suck up all the heat from that weak iron.

Desoldering pumps are unlikely to help. Switch to at least a 45-60w soldering station to do that, or preheat the board with hot air gun or hair dryer etc etc

[jeff6666p]

Re: Soldering question

25w is too low for motherboards.

Motherboards are made out of several layers with thick ground traces that suck up all the heat from that weak iron.

Desoldering pumps are unlikely to help. Switch to at least a 45-60w soldering station to do that, or preheat the board with hot air gun or hair dryer etc etc

If I get a higher watt one then I should be able to get it out?

Is the one good enough?

http://www.radioshack.com/product/in...ctId=12604264#

[mariushm]

Re: Soldering question

Probably not.

All these cheap soldering irons that don't allow you to adjust temperature basically have a small heating element inside that runs at maximum all the time and tries to warm up the tip and everything metal attached to the tip.

It takes a long time to heat up to about 220-250c or whatever temperature they default to and then the tip is so small there's no reservoir of energy/heat to continue to pump heat into whatever you try to work with. The moment you put the tip on the motherboard, all that copper inside the layers of the motherboard will simply cool down the tip and then the iron needs again a minute or so to come back to temperature - IF you're lucky. The whole motherboard can act like a heatsink and continue to pull energy from the tip faster than the time it takes the iron to get back to maximum temperature.

In addition, it looks like that iron comes with a conical tip - that's bad, because if you want to heat something, heat has to flow nice and fast from the tip to the piece, and a conical tip has very small contact surface with the board - heat can't flow fast from tip to board.

See 2c , 3c, 2.4D, 3.2D, even K would be better than conical tips:



It's not worth spending 30$ on that soldering iron even if you're only trying to repair ONE motherboard ever.
If you think you're going to fix other things in the future, try to buy a cheap hakko 888, it will last you decades.

niosales on eBay is authorized hakko dealer in US, they have it for 92$: http://www.ebay.com/itm/Hakko-FX888D...item58abe82d60

or at least try to get a cheap Hakko clone from eBay or stores like Hobbyking.
Hobbyking has a Hakko 936 clone priced at 17$ but it's not stocked in US so it will cost some shipping : http://hobbyking.com/hobbyking/store...h_US_Plug.html

It's not as powerful as a Hakko 888 or other genuine stations but it's way better than those irons like the one you linked to

[ratdude747]

Re: Soldering question

^Agreed. Radioshack's stuff is good for light boards... not a Multilayer motherboards with heavy ground planes (read: thermal radiators that suck heat away).

I'd say my 60W Weller W60P Is almost too weak... On some jobs, even with a 3.5mm chisel tip (no conical tips, they're 100% useless), it feels a tad less than ideal... so I'd say 100W, if you can afford it, is good. As long as your temp is above the melting point of the solder, Power is what determines your performance... yeah, sometimes you have to turn up the heat to get the power output (as that's how a lot of low-end units more or less regulate temps)... I used to use a 30W Xytronic 258... nice for hobbywork, but for actual recapping, it was mediocre at best (some jobs it was fine though, depends on things)

note- no solder guns here. those will fry your board due to the heating method. What's the point of a recap if you ESD (or equivlent damage) the chips?

Sorry for the bad news, but sometimes you just have to have beefy equipment.

[jeff6666p]

Re: Soldering question

Probably not.

All these cheap soldering irons that don't allow you to adjust temperature basically have a small heating element inside that runs at maximum all the time and tries to warm up the tip and everything metal attached to the tip.

It takes a long time to heat up to about 220-250c or whatever temperature they default to and then the tip is so small there's no reservoir of energy/heat to continue to pump heat into whatever you try to work with. The moment you put the tip on the motherboard, all that copper inside the layers of the motherboard will simply cool down the tip and then the iron needs again a minute or so to come back to temperature - IF you're lucky. The whole motherboard can act like a heatsink and continue to pull energy from the tip faster than the time it takes the iron to get back to maximum temperature.

In addition, it looks like that iron comes with a conical tip - that's bad, because if you want to heat something, heat has to flow nice and fast from the tip to the piece, and a conical tip has very small contact surface with the board - heat can't flow fast from tip to board.

See 2c , 3c, 2.4D, 3.2D, even K would be better than conical tips:



It's not worth spending 30$ on that soldering iron even if you're only trying to repair ONE motherboard ever.
If you think you're going to fix other things in the future, try to buy a cheap hakko 888, it will last you decades.

niosales on eBay is authorized hakko dealer in US, they have it for 92$: http://www.ebay.com/itm/Hakko-FX888D...item58abe82d60

or at least try to get a cheap Hakko clone from eBay or stores like Hobbyking.
Hobbyking has a Hakko 936 clone priced at 17$ but it's not stocked in US so it will cost some shipping : http://hobbyking.com/hobbyking/store...h_US_Plug.html

It's not as powerful as a Hakko 888 or other genuine stations but it's way better than those irons like the one you linked to

The one I posted has a adjustable dail for 25W-60W. The reason why the leg broke off is because there is still being a thin layer of solder that I can't really see and the iron I have is'nt strong enough to remove it right?

[Th3_uN1Qu3]

Re: Soldering question

If it goes up to 60W you should be able to remove it. It just needs more solder and flux before it will come off.

[mariushm]

Re: Soldering question

There's big a difference between how those dials work.

Your radioshack iron uses the dial to adjust power going into the heating element. Think of the iron like having 4 elements in series and the dial simply connects the mains voltage to one of the connection points between two elements:

(neutral 120v)->*A*-----*B*-----*C*-----*D*-----*E*
            20w   40w   50w   60w
(active 120v) -------------------^

Moving the dial simply moves the connection increasing the heating element length.
There's no brains in it, the heating element starts heating up and the iron stays at that selected wattage for as long as you keep it turned on.

The heating element stays at constant temperature, it takes time to reach its peak/standard temperature and then it stays there.

These irons have very small heat reservoirs, the tips are thin and small and there's small surface area to transfer heat.

How can I explain... picture this as a cup of tea or coffee....I'll go with tea. When you pour hot tea in your cup, the cup will quickly get hot. Now slowly the cup of team will cool down, but in our example the tea is constantly replaced with new tea of same original temperature and the cup gets back to that original temperature level. The tea is replaced more often than the time it takes the cup to decrease in temperature considerably.

Now, if you put the cup of tea on some metal or some ice cold surface, the time it takes to cool down the cup is much smaller, so even by constantly bringing in more hot tea, the cup will still get cold, as the surface you put the cup on will absorb the heat and get warm.

When soldering, you want the surface to get very warm, so that the metal on the surface will become liquid.

If the power is too small, it's like pouring hot tea into the cup very slowly, it will take a lot of time for hot tea to accumulate into the cup and maintain the temperature in the cup. The surface will get warm because it draws heat from the cup, but the tea in the cup will get cold, you're not getting a very hot surface and you're not getting a hot cup of tea.

Also, if you actually want to heat up the surface you put the cup on, it's important to be a good contact between the cup and the surface. Large areas will transfer heat better, but again it's important to have new heat into the cup of tea, if you want the surface to heat up.

With that radioshack iron, it's like having a pot of tea with an adjustable nozzle which just controls the flow of tea going into a very small tea cup (think whisky glass).
The hot tea slowly pours in at a constant rate but the tiny cup has a very small area touching the surface (cone tip touching large metal traces) so heat doesn't flow well from the small cup into the large metal surface. Also, since the cup is so small, there's only so much hot tea you can fit into the cup so the temperature inside the cup raises slowly even if you pour very hot tea (high power).

The soldering stations I linked to work differently. The dials control temperature. There's a temperature probe inside the tip which monitors the temperature and the station works hard to maintain the tip temperature to the level you set.

Instead of a nozzle that adjusts the flow of hot tea (same temperature no matter what), instead you have a station that makes super hot tea and combines it with cold water to lower its temperature (the station turns on and off the heating element at its maximum power to reach the temperature). Instead of a tiny cup, you also have a big iron with a bigger larger tip, you have a big coffee cup that holds a lot of tea, cooling down slower.

When you put the iron on the surface, the station detects that the surface sucks heat so pushes a lot of heat into the tip to counteract this, it works actively to maintain temperature of tip to your level. Since the cup is so much larger, the heat from the cup goes faster into the surface but there's also a lot more tea in the cup keeping the temperature hot.

I don't know how else to explain it better..,. those cheap irons just don't have the strength for a motherboard.

[jeff6666p]

Re: Soldering question

http://www.amazon.com/Hakko-FX888D-2...=AJ3PYHDIZANTK

I order the hakko one above. It should be enough to do any motherboard type work right? What should I do to get that leg out and what temp should the iron be set at?

[mariushm]

Re: Soldering question

Get a chisel tip when you can. The station is power enough to work with conical tip as well, but a chisel tip will be better.

[ratdude747]

Re: Soldering question

Get a chisel tip when you can. The station is power enough to work with conical tip as well, but a chisel tip will be better.

QFT. Friends don't let friends use conical tips... To the OP, the reason why is thermal transfer (as the flat surfaces of a chisel transfer heat better than the always round (tangental) surface of a conical tip, especially for recapping (as PCB surfaces are flat and leads are long cylinders).

[jeff6666p]

Re: Soldering question

What should I do to get that leg out and what temp should the iron be set at? Which chiseled tip would you recommend for small computer stuff?

[stj]

Re: Soldering question

set the temp to 310

[jeff6666p]

Re: Soldering question

set the temp to 310

So just set it to 310 heat up the solder then using a pump will remove the leg?

[mariushm]

Re: Soldering question

There's no magic temperature.

Leg is stuck there due to a thin layer of solder that binds it to the side of the hole. That solder is lead free solder, which melts at higher temperature than leaded solder.
It's also deep in that hole where your iron tip can't reach easily so heat from your iron doesn't get to that point quite so easy.

Lead free solder melts at around 217c, but since the motherboard will draw heat away from your solder iron tip you would have to adjust the temperature of your iron to a much higher value, so that when you put the tip in contact with the metal in the motherboard even with the metal acting as heatsink, the iron tip will remain above 217c and keeping the solder fluid. 350 to 400c for such cases is not a ridiculous setting. I would dare to say 310c is on the low side.

A simple method would be to add leaded solder (60/40) back to the hole. This serves two purposes: the blob of solder makes it easier for your iron tip to transfer heat into the hole because the surface that's in contact with the iron increases.

The leaded solder melts at much lower temperature and stays liquid while the solder is within a wider range of temperatures. For example, 60/40 lead melts at 183c, so if you combine it with the existing lead free solder that melts at 217c, you will have a mix of solder that will stay fluid at lower temperatures (180-190c), which in turn allows you to use lower temperatures presets on your iron and reduce the risk of damaging traces on the motherboard.

While solder you add flows into the hole, it combines with the lead free solder and the lead (wire) will start to be moving around in the hole, it won't remain stuck to the sides.

Now while keeping the tip on that blob of solder to have everything liquid, you can get a very thin sewing needle and push it gently in the hole... the broken lead should fall out.
If it's accesible from above, you can get some tweezers and pull it out. Just don't keep the tweezers on the lead from the start because then the tweezers will act like a heatsink again.

Alternatively, you can use a bit of lead from a capacitor or a resistor, but these are not that great because solder will stick to them - the sewing needles being stainless steel, solder will not attach to them.

After you're done, you can get the solder sucker and suck away the blob of solder you added.

[c_hegge]

Re: Soldering question

I've always gone with 450*C (when my temperature controller was working, that is)

[stj]

Re: Soldering question

want to make a new iron controller?
i just found a few projects yesterday for just that!
(amazing coincidence)