Surface mount component soldering
 

Here's a technical one guy's.

For those of you who are modding esc's or make a living with integrated circuits, what techniques and tools do you use for dealing with SMT components?

Example: fried FET(s) on a printed board with SMT.

How do you remove the bad part?
How do you clean the board?
How do you prepare (for) the new part?
How do you attach it?

I recently came into this scenario (bad fet, though mine was soldered over a tiny SMT resistor, manufacturing defect). I tried prying up on the fet while heating the solder joints, cracked the fet in the process :diablo:
Anyhow I removed the offending resistor and cleared the pad by first adding new solder, then using the solder sucker to remove the bulk, then cleaned the pad the rest of the way with a solder wick.
I am waiting for new part to show up but I plan on adding a small amount of solder (low melting point type) to the pads on the board and keeping it melted with a hot air blower (attacment to a butane torch) and then setting the fet into place. I have seen that I can also solder from the pads to the tabs with the fet in place as I bulked up some of the other weaker joints on the other fet's...

What is your MO? (modus operendai)? >mode of opperation<?

1. Hot plate
2. Electronics cleaning solvent (Acetone will do the job, but not recomended)
3-4 Use solder paste and hot plate or oven

How do you remove the bad part?

I use a hot air butane blower to heat the soldered legs of the chip to be removed and lift it off using tweezers once the solder melts

How do you clean the board?

Isopropyl Alcohol works well or electronic contact cleaner will do the trick.

How do you prepare (for) the new part?

Solder flux pen works well to prepare the contacts or touch up the solder on the board with the tip of the soldering iron.

How do you attach it?

Make sure the surface is clean and fluxed I reheat melt solder with hot air or use a soldering iron to touch the legs.

Won't work for Power MOSFETs (with solderable tab) and with PCB layout with improved heatsinking.

Correct Artur, hence the cracked fet :whistle:

The hot plate is a great idea, I handn't found that techinque in any of the research I've done. Makes perfect sence though, heat the entire unit up (use the heatsink property of the pcb to your advantage) then deal with the individual part.

What temperature are you using? Do the other components become fragile (movable) at that temp or do you run the plate below the melting point for the solder then use some kind of local heating?

That is simple, identify melting temperature of the solder (take a small amount and put it on heat plate while raising temperature) then use for entire board.
And, yes everything becomes loose, so carefully remove the part you do not need and put new one in. (Solder paste or Flux and solder with capillary effect will make your life easier).

A friend of mine once had an issue with a microprocessor in a beamer; i remember he removed all the shrink wrapped items and put it in an oven.

you can get very tiny blow-holes for a paint removing. If you know a certain part is damaged, just put the soldering iron on that particular part and let the heat flow through..

You can solder an SMD part with a very small tip on the soldering iron. Remove the tin from the board before you start soldering though, otherwise there might appear a weird tension in the part/weld to remove tin you can use litze.

I've acutally used a heat gun to remove smt components. It heats up a wide area and makes short work of heating up large ground planes. Just be sure to use the low setting, otherwise some of the components might fly off of the pcb.

Just be careful when using this method or a similar method. When the item is in its melted state, a simple sneeze can send components flying. Don't ask me how I know that.

The hot plate thing rocks, I had to use the oven for a little preliminary work (extending the bus wires between the MM boards) I only heated the board to 325'f but it made it so much easier to get nice solder joints on the bus/board connections.

Ive got a friend with a hot plate, his dad uses it for jewelry work, I'll use that when I put the fet back on. I'm not going to heat the entire board up to melting point but I'll keep it as close as I can and use additional localized heat to attach the fet.

(so excited to try this the new fet should be here tomarrow). Only wish I had read about the hot plate prior to breaking the fet... oh well live and learn.

Thanks for the info guys!