Possible disaster. Do ICs have an orientation?

[ferrinbonn]

Ugh, I think I might have screwed up. Here's what I'm building and what I've done so far.

http://imgur.com/Q3ZYfWT
http://imgur.com/xafD9Qf

I just realized, after having soldered everything, that the diagram shows a notch in the IC on the left hand side. The IC I used didn't have a marking like that, but rather a small dimple, which I oriented to the upper right. Now I'm thinking that the orientation of the IC matters and that I might have put it in backwards. Did I just majorly screw this up?

[Muadzin]

The notch usually is the upper side of an IC. If there is no notch then the dot performs the same function. So if the notch on the board points to the left and you put the dotted side to the right, then yeah, you inserted it the wrong way. Good news is, if you used an IC socket, you did use one, right, then you can just flip it over. It has happened to me tons of time too and just flip it over and it should still work.

If however you soldered the IC directly to the board then you're boned. It takes skill and experience to desolder an IC without ruining it. You can desolder it, but the chance of frying the IC increase significantly. In which case let this be a learning experience, don't solder IC's or transistors directly to a board. Unless you got the soldering chops to pull it off and did not make any mistakes.

[ferrinbonn]

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Nope, no socket. Soldered directly to the board, which is what the instructions suggested. Lesson learned I guess.

So, the good news is that I ordered an extra IC in case I screwed it up. So I can go ahead and fry the IC, as long as I can get it off without ruining the board. Any tips on how to best do it?

[Stomptown]

You did put it in backward but don't freak out. You can remove the IC but since this will be your first time attempting to remove an IC I would not even try to save it. Here is what I would do:

Supplies:
1. Vice (to hold PCB while desoldering IC pins)
2. Wire lead Cutters
3. Needle Nose Pliers
2. Solder sucker
3. New replacement IC

Steps:
1. Take a pair of wire cutters and cut all 8 IC pins as close to the body of the IC as possible
2. Place the PCB in the vice in a vertical position
3. use needle nose pliers to grab and pull out one of the IC pins while heating the PCB pad from the back side with soldering iron (repeat for each pin)
4. once all IC pins are removed, heat each pad again from the backside and "suck" the solder out of the PCB pad from the font side with you solder sucker.
5. replace IC

If you follow these steps you should be able to remove the IC without damaging the PCB.  Just make sure to cut the IC pins close enough to the IC body to give yourself something to grab onto with your needle nose pliers. FYI, there are other ways to do this but I am recommending this based on the assumption that you are new to this.  You could potentially save the IC and use a solder sucker or soldering braid to remove solder from each pad without damaging the PCB, however it is not an easy task. If you want to give it a go I'm sure there are plenty of tutorials on how to do it. Just realize that overheating the pads can easily lead to damage to the PCB (no matter what method you use). This method just allows you to clear all 8 pads one at a time, which increased the chance for success.

Good Luck!

Jon

[m-Kresol]

if you have an extra one, you are in the safe zone.

I strongly suggest the following: cut the legs of the IC very carefully, so you don't damage the board by scratching through the solder resist. Then heat the pads, and pull out the leftover piece of leg. Then use a desolder pump to clean the pad. Once you're done solder in the new IC with the dot to the left. The dot marks pin 1.
This is the better option than to try and desolder the IC in one piece. You would have to either desolder the pins very cleanly to get it out or heat all 8 pins simultaneously and lift it out. The only time I lifted pads was when desoldering an IC.. ymmv


EDIT: Jon beat me to it. good to see we share the same opinion

[Stomptown]

if you have an extra one, you are in the safe zone.

I strongly suggest the following: cut the legs of the IC very carefully, so you don't damage the board by scratching through the solder resist. Then heat the pads, and pull out the leftover piece of leg. Then use a desolder pump to clean the pad. Once you're done solder in the new IC with the dot to the left. The dot marks pin 1.
This is the better option than to try and desolder the IC in one piece. You would have to either desolder the pins very cleanly to get it out or heat all 8 pins simultaneously and lift it out. The only time I lifted pads was when desoldering an IC.. ymmv


EDIT: Jon beat me to it. good to see we share the same opinion

Yep! I still do it this way for the most part. I'll take ruining a $0.50 IC any day over potentially damaging a PCB. And this is why we use sockets for the expensive ICs (most of the time). 

[ferrinbonn]

Thanks guys. I got the old one out successfully I think. New one should arrive in the next few hours and then I'll see if I can get this thing done.

[m-Kresol]

good to hear. If you have any questions, no matter how noob-ish you think they might be, don't hesitate to ask

[matmosphere]

I'm surprised, I desoldered ic's before and never damaged the board or the IC. If you have a solder sucker or desoldering wick it should be a manageable job. Just go slow and give it time to cool off between each pin.

[Muadzin]

With IC's and transistors it never hurts to use sockets. With IC's they're never gonna fall out so why make things difficult for yourself? Transistors, slightly bigger chance of falling out, they have only three legs to hold them, as opposed 8 legs or more. But if you're really worried you could still apply some solder to one of the legs inside the socket. Once you've verified that everything works of course.