how-to solder SMD capacitors

[vtboy2k]

Hi, I've been a long time reader of this forum but finally registered. I've just received a Toshiba laptop with bad SMD capacitors. Was wondering if there's any guide on how to desolder and solder in the SMD capacitors. There's a picture of the four silver capacitors I'm trying to replace in the following post (last post) here

I have ordered the following Panasonic SMD capacitors .

Thanks in advance.

[Player2]

Re: how-to solder SMD capacitors

The best way is to use a hot air station to heat up both leads and then pick it off with tweezers. If you don't have access to this, you can try alternately heating one side, pulling the cap up a little, heat other side, pull up a little, etc; but using this method it is very possible to peel or damage the traces.

[Toasty]

Re: how-to solder SMD capacitors

2 soldering irons and a helper to pick the cap off.

[Krankshaft]

Re: how-to solder SMD capacitors

More soldering stations like the Hakkos also have tweezers to remove 2 lead components like this.

These for the 936-937 models:

http://hakkousa.com/detail.asp?PID=1265&Page=1

This one for the FX-951:

http://hakkousa.com/detail.asp?CID=&PID=2401&Page=2

The alternate lead heating method always worked for me and I've never ripped a trace myself.

Hot air is good as long as you control where you're applying it and don't apply it for too long otherwise you will do more harm than good to nearby components.

[Toasty]

Re: how-to solder SMD capacitors

Hakko's nice, but they're not for the occasional repairer/weekend warrior (unless you can't find enough ways to blow your cash). Just waaaaayy too much money. $200 for 2 soldering irons and a hinge???!! WOW!

[i4004]

Re: how-to solder SMD capacitors

http://www.mcmelectronics.com/product/21-8230

[Toasty]

Re: how-to solder SMD capacitors

Now that's more like it! Nice catch.

[vtboy2k]

Re: how-to solder SMD capacitors

hmm buying the soldering equipment does add up quite a bit. might have been cheaper if I had sent it to a repair shop

[Krankshaft]

Re: how-to solder SMD capacitors

$200 for 2 soldering irons and a hinge???!! WOW!

Hey! Those are two temperature regulated irons and a hinge .

Some Hakko stuff you can find real cheap shipped from China got the 200 dollar (FG-100) tip temperature thermometer for 53 bucks shipped. I opened it up and checked it out it was 100% legit. It just shows you how much of a cut people get before it gets to your door.

Unless you're doing loads of SMT caps day after day then it's not worth it for a special tool. Heat one leg tilt heat the other.

Nice find on the Tenma tweezers I have their isolation transformer and HV probe they are both well built.

[Toasty]

Re: how-to solder SMD capacitors

>>Hey! Those are two temperature regulated irons and a hinge.<<
My bad.

>>Some Hakko stuff you can find real cheap shipped from China got the 200 dollar (FG-100) tip temperature thermometer for 53 bucks shipped.<<

Ahhh-soooo! You have Hong Kong Connection.

Pray tell! Dammit!

Toast

[i4004]

Re: how-to solder SMD capacitors

>hmm buying the soldering equipment does add up quite a bit. might have been cheaper if I had sent it to a repair shop

32$ for soldering tweezers is too much?

and if you don't want that(and already have soldering iron), then do what krank said
"Heat one leg tilt heat the other."
are you afraid you'll hurt that bad cap upon removal?
<wink>

also, there are alot of video gudes on youtube etc.
see
http://www.curiousinventor.com/guide..._Soldering/101
(see portion at 7'09'' at that video)

[Krankshaft]

Re: how-to solder SMD capacitors

You'd probably get plowed with the hourly rate to replace these components and I can tell you it's going to be way more then 32 bucks or the cost of a soldering iron and solder.

From my experience most places are just going to try to sell you a new motherboard anyways. There are so many so called "techs" out there that are nothing more than module swappers.

[Tube_Dude]

Re: how-to solder SMD capacitors

Some Hakko stuff you can find real cheap shipped from China got the 200 dollar (FG-100) tip temperature thermometer for 53 bucks shipped. I opened it up and checked it out it was 100% legit.

Hi Krankshaft

I got one of this too. I presume the multiturn pot is for calibration, but there is one another little trimmer too. Have any idea of the calibration process or what each trimmer does?

Thanks!

[dossman]

Re: how-to solder SMD capacitors

http://www.mcmelectronics.com/product/21-8230

This looks like something I could use, now all they need is a little vacuum cup that comes down and lifts the chip up.

[magicknees]

Re: how-to solder SMD capacitors

One thing you'll need is a good way to see what you're doing. I have a stereo microscope (thanks to my last job going out of business sale) as well as a headgear magnifier. It is amazing when you can really see what you're doing how much easier it is. It is easy to see if you've had too much caffine too (you shake alot).

The head gear is cheap, $20 or so. My stereo microscope is worth $900 new. It is not for sale btw. I use it all the time. You can see bad solder joints and smd caps look like wooden blocks the kids play with. The soldering iron looks like a 6" log.

enjoy

[tronxkid]

Re: how-to solder SMD capacitors

I use lots of low-end equipments and I find them quiet useful for sometimes. For your question the best answer I can give is to buy a cheap 50$ hot air station. KADA is a good low-end brand.

de soldering using soldering iron is a risky thing. too much heat and too much force can easily erase traces on the pcb.

[Longbow]

Re: how-to solder SMD capacitors

Undoubtedly, high tech soldering/desoldering equipment can make this job easier. I have never owned or used it however. Keep in mind that 50% of the SMD lead is underneath the part! Directing a hot air gun at the part can often desolder a number of nearby parts as well, and blow them off the board if the parts are small - like SMD resistors for example. You don't want that.

Here is a method that worked well for me for SMD caps in most cases. Get yourself a some good flush cutters and cleanly clip off the cap as near to the bottom as possible (depending upon clearance, size, etc.) The cap will then come apart very easily with a little help from a dental tool at which point each leg can be desoldered individually. I found that this method avoided lots of broken and overheated traces and in general made the job possible. In many cases, the caps can leave electrolyte on the pc traces, which has to be cleaned off. It eats away the copper traces and worse, the electrolyte travels along the traces underneath the green coating, and may dissolve traces some distance away from the bad cap. Check continuity if in doubt.

[Evil Lurker]

Re: how-to solder SMD capacitors

I have taken an aluminum crimp terminal, filed the outer edges till somewhat sharp, then bent it to where it can heat both sides of a SMD simultaneously and mounted it on the end or my iron tip. Then I simply used a pair of tweezers to pick it up.

I had thought about taking a pin and superglue the tip to the SMD, put a drop of water on it to instantly harden the glue, and remove the glue via the appropriate solvent.

For resoldering use mechanics soldering paste, the kind where the solder has been ground or mixed up in the flux and then simply touch each side with your iron, or hit it with some hot air.