Maker Pro
Maker Pro

Hobbyist Techniques for Reflow?

chopnhack

Apr 28, 2014
1,573
Joined
Apr 28, 2014
Messages
1,573
What are your techniques? With the continuing push for smaller, fewer products will be available in hand solderable packages. As a hobbyist, how are you contending with the issue? I have seen reflow done on youtube in a toaster oven! Has anyone tried using a heat gun?
 

OLIVE2222

Oct 2, 2011
690
Joined
Oct 2, 2011
Messages
690
I have seen solder plate method videos and its look pretty good. I have personally used the paste (via a dispenser) and a dedicated oven. Results are correct but I still prefer the plain old solder iron method up to 0402 size + desoldering braid and flux for fine pitchs IC. I apply a simple rule, if I can't perform a visual inspection of the result (solder pad under IC, BGA,...) I go for professionally made assy. No doing so involve more soldering debug issue than design debug issue.
Olivier
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
I limit my hand soldering to 0603 or larger.

On small devices I use solder paste unless I'm replacing a component -- In that case it's often easier to tack it in place with whatever solder is on the pads.

0.65mm pitch is the narrowest I'll do willingly, but I've done 0.5mm pitch by hand. The hardest part is really getting things aligned.

I have a rework tool as well, and although I can do a lot of stuff with an iron, there are times when hot air is just a lot better.

Oh, it also helps to be an octopus.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
Yeah, I'd probably do it a little quicker. Also, you may not have the luxury of being able to hold the device down with your fingers. That's a pretty big chip.
 

chopnhack

Apr 28, 2014
1,573
Joined
Apr 28, 2014
Messages
1,573
Yeah, I'd probably do it a little quicker. Also, you may not have the luxury of being able to hold the device down with your fingers. That's a pretty big chip.
Maybe do opposite leads to tack in place?
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
I have not tried reflow yet. I've soldered 0603 and SOT using paste and then just touching each side with tip of the iron. I've soldered 44 pin SSOP using drag method (tack two corners, then drag a blob of solder across all the pins on one side, making a mess, and clean up with desoldering braid). That method is actually faster than soldering the individual pins on a PDIP. I concur with Steve that getting the large chips aligned is hard part.

If you go to Sparkfun, they have an interesting method of doing reflow with an electric skillet that I think I will try if I ever need it.

Bob
 

chopnhack

Apr 28, 2014
1,573
Joined
Apr 28, 2014
Messages
1,573
I tried my hand at removing some SMD's today. It is apparent to me that my crappy iron is not up to the task - simply doesn't put out enough heat! All the videos I see, it just takes a touch, while my iron has to sit on the component for quite some time before the solder flows. I did pre tin my tip and use a flux pen ;-) I attached a pic of some of the pieces I pulled off a scrap board. Luckily I was able to find two soic-8 chip that are the exact size of my next project to practice with :)

Can anyone recommend a good soldering iron?

007_zpsd78509f9.jpg
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
It is quite possible that the boards you're trying to desolder parts from are using unleaded solder which melts at a somewhat higher temperature.

If the board has large areas of copper, this may also make life hard for you.
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
Did you use a solder sucker or copper braid? It is very hard to remove parts with just a soldering iron.

Bob
 

chopnhack

Apr 28, 2014
1,573
Joined
Apr 28, 2014
Messages
1,573
Did you use a solder sucker or copper braid? It is very hard to remove parts with just a soldering iron.

Bob
Copper braid, I don't know whether it was the old solder or the iron itself. I fluxed the terminals just prior to applying the braid and heating the terminal, some posts would go liquid quickly, most did not. The smd's came off fairly easy - I actually had more trouble with the through hole parts, some were soldered top and bottom? I don't know if that was just excess passing through the hole or something else.

Aside from a good iron, (which I still could use your recommendations on) is there a particular flux that is better? I have seen some being used in videos that was much more viscous, seemed like it worked better.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Joined
Jan 21, 2010
Messages
25,505
For surface mount devices there's often nothing else to do other than to melt all the solder and lift the device off while it's still molten. This is where hot air really comes into its own.

The removal of through hole components is almost always exactly opposite. You remove all the solder and let the device fall out. To highlight this difference, sucking is often the best approach.
 
Top