SMD soldering and other magic

[kendrick]

Tertially related to gaming, I recently resurrected an HP Omnibook 530 for the purpose of playing old DOS-based roguelike games. Of course, a week later I immediately killed it by screwing up the power supply. The boot-up beep codes indicate that the memory is bad, and of course they're not on a removable daughterboard but are on the main board as surface mount chips. I have replacement parts at the ready, and all I lack is experience.

Anybody mind sharing some wisdom when it comes to SMD soldering? I've not done it apart from adding mod chip jumpers and wires, and the experiments I've done on my trash boards have been big messes of solder and flux everywhere. I don't think it's strictly necessary to spend thousands of dollars on a specialized station just to replace two tiny chips.

-KKC

[blackevilweredragon]

how i did this without a re-work station, was take a small knife, and pry off each leg..  you end up with a nice empty spot on the board..  then i placed the new chip down onto it, and held pressure, while i soldered on each pin..

be sure to start with one pin, then wait just a little, and then do the other side..  you'd want to evenly distribute the heat, as to not cook one side of the chip...

[kendrick]

Desoldering and removing the bad component is my big worry. Did you pry with or without a heat source? You always learn that you heat the work and not the solder, but in this sort of case I get the feeling you should heat the secondary tool and stick the iron on the knife.

-KKC

[blackevilweredragon]

Desoldering and removing the bad component is my big worry. Did you pry with or without a heat source? You always learn that you heat the work and not the solder, but in this sort of case I get the feeling you should heat the secondary tool and stick the iron on the knife.

-KKC

I didn't use heat..  But don't forget, I push boundaries  .

Remember in the Genesis mod you have to lift the leg of the 315 chip for the region mod?  I used that technique, except on ALL the pins, until the chip was loose and able to come off..

[GUTS]

You could also try one of those desolder pumps, I have one that you click down and then hit a button and it suctions off the solder, it works really well.  I use it to remove any excess solder so that pins are easier to pry up, it game in handy when I was trying to make some SNES carts.  You basically just heat it up and then SUPER quickly tilt it over and hit the button as you pull your iron back, it'll suck all the solder right off if you're fast enough.

[blackevilweredragon]

You could also try one of those desolder pumps, I have one that you click down and then hit a button and it suctions off the solder, it works really well.  I use it to remove any excess solder so that pins are easier to pry up, it game in handy when I was trying to make some SNES carts.  You basically just heat it up and then SUPER quickly tilt it over and hit the button as you pull your iron back, it'll suck all the solder right off if you're fast enough.

those don't work really well for surface mount stuff...

[NeWmAn]

If you are SURE the parts are defective, the easiest way to remove ICs would be to cut all the legs close to the body of the IC, and then heat and remove one leg at a time.


If you check on youtube you can find some interesting videos that can help you to learn  how to work on SMD parts:

http://www.youtube.com/watch?v=B55JajzCcvE

http://www.youtube.com/watch?v=t5Xlp8MYqJc

http://www.youtube.com/watch?v=yN_0Y7D2qFY

http://www.youtube.com/watch?v=AxYhF6Ab2CU

http://www.youtube.com/watch?v=_evj0_qEeII

[kendrick]

Cool, thanks for that. I have a sneaking suspicion that other parts on the board might also be bad, but for sure these two chips needs replaced. Part of my problem is that my donor parts also have to be lifted off a separate board whole, but I'll deal with that later.

It's too bad Youtube uses Flash. I started blocking Macromedia content years ago when advertisers started using it heavily.

-KKC

[Segasonicfan]

I do almost all SMD work now so I can tell you there are definitely a lot of techniques out there.  If it's a reasonably small chip like an 8 SOIC I actually just cake the sides in solder.  Quickly run the side of your iron against each set of pins while using tweezers to pull the chip upwards.  It really doesn't take much to get em off.  Also, if you are doing a lot of SMD work I'd say you have to have an adjustable temp soldering iron for obvious reasons.

-Segasonicfan  

[kendrick]

Well, this is interesting. Apparently the need for small-scale SMD repair and retooling means that more manufacturers are creating the hot-air interfaces at a lower cost. I've seen hobbyist-level SMD stations for around US$120 or so. I can spring a couple of day's pay for a station and the tips I'd need to do this work. It would make Xbox repair a whole lot more satisfying too.

-KKC

[viletim]

Kendrick,
Swamp both sides of the chip in solder and attack it with two irons. You can use just one iron but it's a lot slower (works well with TSOPs still). Remove all the extra solder with solder wick and don't clean off the flux (it makes soldering the new part easier).

I don't think it's possible to to remove QFPs, PLCCs, and other chips legs along all four sides unless you cut off all the legs or use a hot air gizmo.

When you solder on the new chips, use very fine solder. For the high density .5mm pitch chips you'll need a fine soldering iron tip too.

I think you'd do better just junking the PC and buying another one, especially it it was damaged by a faulty power supply.  

[kendrick]

Yeah, but it's a beauty. The idea of a 486 that runs on AA batteries appeals to that anti-social, survivalist nutjob hidden in my head. :) If I can fix this puppy, I'll consider it a job well done.

-KKC

[kendrick]

So I'm browsing around looking at the SMD soldering guides. Most of them don't apply to me because they're assuming you won't reuse the old part. While I'm looking at cheap SMD stations I come across this:

http://www.web-tronics.com/chipsmdsolre.html

Anybody work with this Chip Quik stuff before? My hackles are up, only because the thing looks slightly too good to be true. On the other hand, it's only a $20 risk as opposed to a $400 risk or more with a dedicated station I may only use once in my life.

-KKC, who fixed his Game Gear, yay! Now I can do it for everybody!

[kendrick]

I thought you guys would get some amusement out of the long-term followup. To make a long story short: My girlfriend got me an SMD soldering rework station as a late birthday present. After practicing on some old PC motherboards, I was ready to swap some memory chips on that laptop. Good news is, I swapped it successfully and made solid contact with no shorts. The bad news is, after I powered up the laptop for real it caught on fire. That indicates to me that there was something else wrong with it other than the memory. The house is still standing and nobody's hurt, so I'm cutting my losses and quitting while I'm ahead. :)

Incidentally, you guys might have an interest in the new Asus Laptop that's been announced. The Eee is a P-3 800 Mhz machine with a 7 inch screen, built in wireless networking and a solid-state drive. All the chips are low-power, and the thing is going to be preloaded with some build of Linux. Total cost to the consumer, $200 or less. That's going to be my replacement hardware when it gets released in August.

-KKC

[blackevilweredragon]

don't those things look like kids toys, because they were designed for kids in need of a laptop?

anywho, got myself an SMD Rework station too...  been enjoying removing a LOT of chips off old cards..

http://blackevilweredragon.spymac.com/smd.jpg