"How screwed am I?" , A soldering question

[trunolimit]

I was taking apart a notebook and got frustrated so I dug a kitchen knife into it trying to release those pesty tabs. in doing so I managed to knock out a small chip. it looks like an and gate of some sort. all the leads are still intact, just a bit bent, and I know exactly where it came from. it's a surface mounted chip with not a lot of wiggle room between leads so I want to know if and how I can solder this thing back on. I was hopping that it wouldn't be an important part of the motherboard but the computer won't boot now that it's without that chip. I'll include pictures soon so you guys can see what I'm trying to solder back on

[tehboris]

Voltage regulator or capacitor?

[trunolimit]

Voltage regulator or capacitor?

its black, and has about 4 or 3 leads going out of the sides. its not a capacitor or resistor I know that much. I used and/nor gates in my electronics class and it looks like that so I'm guessing it's some sort of gate (is a gate a voltage regulator?)

I looked on youtube and found a couple vids that made it look easy. I guess I'd have to unsolder what is there now and then solder back the little chip.

[patrick-revision3-com]

Check out the "Surface Mount Soldering Tutorials" section at SparkFun.com's website:

http://www.sparkfun.com/commerce/tutorials.php

Re-soldering surface mount components sucks, and you might have to do it a second time if the thing has been damaged, but you can do it with a decent soldering iron and wick.

A hot air rework station makes it heaps easier, but I've never had the luxury o' one.

[magicbobert]

Sounds like an SOT package. Does it look like this?

http://www.national.com/images/pkg/mf03a.jpg

That could be a lot of different things. They make transistors, voltage regulators, diodes, and all sorts of other components in the SOT package. As surface mount parts go, that's one of the easiest to solder. You should be able to get it back on without too much trouble.

[computoman]

What a chance for a "Johnny Carson" moment....

http://www.google.com/search?hl=en&q=home+made+hot+air+soldering+iron&btnG=Search&cts=1236228315668

[kiwifrog]

[QUOTE=trunolimit;498372]I'm guessing it's some sort of gate (is a gate a voltage regulator?)
[QUOTE]

HE HE :) Did you learn anything it that class.

If the Chip has fallen off completely then buy some rubbing alcohol, solder-wick(soderwick in your land), Flux, and a semi decent soldering iron (with a round tip would help.)

You need to clean the pads with the Soderwick, then clean the pads with some alcohol, Re-tin the pads leaving a small bulge of solder on each(you won't overhead the PCB they're quite robust).

Then position the dislodged chip over the pads solder just the corner pin to hold it in place, move it carefully till all the pins are lined up. Then apply the flux, after that pass the iron over the pins. If the iron is the correct temp and there's enough flux, the solder will just flow like mercury not connecting any pins together.

If you manage to link a couple of pins, just reflux then reheat, the solder should transfer to the iron.

If the chip is still connected, buy some Chip Quick, and follow the instructions for removal, chip-quick had some really good flux that come with it too.

BTW, you can purchase a gas soldering iron(weller portasol), they have a hot air attachment. Mine is temp controlled, and before discovering chip-quick was the way we removed all our smd devices. Cost me around $nz140 that's around $65 your money. And having tried a $3k machine on apro, found the portasol just as good.

Mike.

[trunolimit]

[QUOTE=trunolimit;498372]I'm guessing it's some sort of gate (is a gate a voltage regulator?)
[QUOTE]

HE HE :) Did you learn anything it that class.



yeah I did learn that electrical engineer was not my cup of tea. needless to say I have changed majors.

Sounds like an SOT package. Does it look like this?

http://www.national.com/images/pkg/mf03a.jpg

That could be a lot of different things. They make transistors, voltage regulators, diodes, and all sorts of other components in the SOT package. As surface mount parts go, that's one of the easiest to solder. You should be able to get it back on without too much trouble.

yeah it looks like that except more flat and it has 8 leads not 3, really tiny little things. I'll go check my local radio shak to see if they have wik and flux. looks like I have a lot of homework to do, thanks guys.

[trunolimit]

What a chance for a "Johnny Carson" moment....

http://www.google.com/search?hl=en&q=home+made+hot+air+soldering+iron&btnG=Search&cts=1236228315668

i dont get the Jonny C ref but this would have been a great "let me google that for you moment"

[magicbobert]

yeah it looks like that except more flat and it has 8 leads not 3, really tiny little things. I'll go check my local radio shak to see if they have wik and flux. looks like I have a lot of homework to do, thanks guys.

Ah, an SOIC chip. A little more difficult than an SOT, but probably still doable. Radiomarkup should have solder wick. I'd just get some standard rosin-core solder and be done with it.

[davmoo]

Yes, Radio Closet has solder wick. I just bought a roll day before yesterday. 64-2090, and I think it was $3.99 for a 5-foot roll.

[trunolimit]

I can't thank you guys enough for your help. here are some iPhone pics of what I was up against

I had to solder this
http://i24.photobucket.com/albums/c42/trunolimit/Picture2002.jpg

onto this
http://i24.photobucket.com/albums/c42/trunolimit/Picture2001.jpg

and to my surprise it worked. I found an old ram stick that had the same kind of chip and practiced on it. Having the wick helped a lot I cant believe I use to do everything with that POS suction thing.

one thing I still don't understand is the flux. I used it because the directions said too but what is it for and what does it do? I felt like I would have gotten the same results without it.

once again thanks to everyone in the forum for the advice.

[kiwifrog]

one thing I still don't understand is the flux. I used it because the directions said too but what is it for and what does it do? I felt like I would have gotten the same results without it.


The flux works a little like an acid, It'll clean the skin on the legs and makes it easier for the solder to stick/flow. Keep in mind the brown liquid coming our of the solder is flux also(but has to melt first). The job could be done without the flux, but wouldn't be quite as easy or as tidy.

Mike.

[magicbobert]

Yep, the flux acts as a cleaner to make sure you get a good connection. A lot of electronics solder nowadays is rosin core, which basically has flux in it, so a lot of people (myself included) don't flux as a separate step anymore.

As far as solder suckers go, yeah I'm not a fan. Most of the small ones are crap. The only time I've had success with a solder sucker was when i couldn't get the wick in underneath a surface mount VCO I was soldering, and I had access to a massive sucker. The thing was about the size of a C or D cell Maglite. That actually worked really well, but only because it was so huge.