Changing SMD parts

[merlinb]

Although I did once get compliments on my chopsticks technique in Japan, I think that these would be easier than two irons:
http://www.mcmelectronics.com/product/21-8230

You can't handle one iron in each hand? What are you, Shrek?

[Goodrat]

About the 14 pin IC, yeah, add enough of a pool of solder down each side and off it goes.
I supervised and reworked in an SMT dept for a few years and we often didn't have the proper Metcal iron tip and we took a few shortcuts
Heating solder paste with a heat gun... I'd be afraid to burn the board.

[pickdropper]

Yeah, burning the board can be a risk.  Reflective aluminum tape can protect the board and other components when using the heat gun.

[Govmnt_Lacky]

Heating solder paste with a heat gun... I'd be afraid to burn the board.

I would think that if you used the appropriate heat that it wouldn't burn it. I suppose it would be a fine line between what would heat the paste and where the board starts to sizzle 

I like the solder paste idea.... don't go squashing my dreams already!   

[pickdropper]

It really depends on the package.  If it's just a resistor, cap, or standard SOIC IC, they CE up pretty easily.

If it is a TO-220 with the heat sink attached to the board or an IC with a thermal pad underneath it, it is likely to need quite a bit more dwell time to get everything flowing.

Also, check out the videos for Chip Quik.  I've never used it, but some folks swear by it.

[R O Tiree]

I always add fresh solder to both sides to get things flowing and hot, then moving side to side however many times it takes, probably 3 or 4.
Enough time to get the solder very hot, but quick enough to heat the other side before the other cools.
With a slight push to one side while you are doing this, the part will slide. Just swipe the part away with the iron. I've taken off 14 pin IC's that way.
Yeah, have a light touch around small pads. Damage risks will depend on board quality.

By adding more solder before you start, you are actually adding more flux as well by default. As Ice-9 says, flux is your friend and his advice about the no-clean stuff is good info.

SMT soldering relies a lot on surface tension to pull the parts into line on their pads. Add more solder and you're making your life more difficult. That said, adding more solder will mean that there's more mass, so it will take longer to cool back down, which is why you've had success with removing 14-pin chips. Keeping the board heated up for longer will, however, increase the risk of damage to the PCB, as you alluded to.

[tubegeek]

While we're on the topic of SMD, I hope everyone here has seen this little bit of DIY genius:

http://www.frantone.com/designwritings/design_writings.html#hold

"DIY Hold Down Tool for SMD Parts "

[J0K3RX]

You have to watch when removing some surface mount parts as they will have a small dot of adhesive under the components which you will fight with when trying to get the component off. There is a technique to getting these part off which I really can't describe, it's just something you get a feel for and you learn to get around it if you don't have special equipment... Hot air pencils are great if you have one or have access to one but for the sake of time I usually just add A LOT of solder to each side of the component while jumping back and forth from one side to the other until I get both sides to flow at the same time. When the solder is flowing I just sweep the part off to one side. This is also something you have to get a feel for or you can lift pads, traces etc.. I have removed large quad packs with this method without lifting one pad but it's a bugger to do! A straight up hot air gun works great also but you run the risk of thermally damaging the component or other surrounding components since the heat is not focused on a small area, and obviously you can burn the board... You could use insulated tape to cover surrounding parts but that will only give so much protection. It's ok for certain parts like resistors, caps etc.. but I would not use a heat gun on IC's and there really is no need to anyway, they are fairly easy to solder by hand.. For most pedal work you really won't need big fancy shmancy rigs to get the job done well.. There is a lot of feel, technique and trial & error but it's really easy once you catch onto it! You can get really fast at placing parts and tacking them down and you can do it in a fraction of the time it takes to replace or install through hole components!

Also, there are special solders you can use for SMD with water soluble fluxes that work awesome and leave zero residue or flux on the board. They are a little more expensive but solder goes a long way with SMD and it's well worth it! Plus, your solder joints look factory like sparkling diamonds... Some military spec and medical contracts require the use of this stuff and there can be no flux left on the board what so ever..  Not necessary with pedals but sure looks damn good!       

[merlinb]

A clever way to heat the legs of ICs:

[tubegeek]

A clever way to heat the legs of ICs

Ooh, no kidding! Thanks, O Wizard!

[R.G.]

There have been some similar items in the past. One was a long "U" of metal with a similar shape, intended to heat both sides of an inline package at a time. There was even one system in a quad setup to fit quad flat packs. The advantage to a pre-made tip is that it can be threaded into the end of a soldering iron and get good heat transfer. The only difficulties I see with the bent-wire-paperclip style is how to get the heat into it. It would be neat if it had an end threaded to go into a threaded soldering iron,

My experiences with the big U style is that they have to be heated up quite a bit and loaded with solder to get enough thermal mass to melt the solder on the pins and in the holes of a plated-through board. That's one thing that made the tweezers so attractive - there's a 40W iron on both sides. It heats fast, and melts the solder on the leads fast. It also provides some help in lifting the IC. It's outright easy on Rs and Cs.

That's the other issue with the big U and folded-wire setups - you still have to work something in under the IC to lift it while its soldered leads are molten.

One other incremental thing that works is stainless-steel shim stock. This can be slid between the pad and the lead while the solder is molten. This can be done lead by lead. Works on non-IC stuff too, but requires more manual dexterity.

[pickdropper]

Yeah, tweezers are great.  I finally ponied up for a pair of these: