[winston61]

Can anyone offer any insights, tips, tricks for soldering surface mount? Never done it, but gonna try. Thanks to all.

 

[KTpG]

Don't drink caffeine
Use small soldering iron tip (and lower wattage iron to control how easily the solder will flow)
Use small solder
Steady your shaking hands (my hands shake... especially when I am trying to be careful....)

 

[stereth]

I had to solder some surface mount parts, including 50-mil chips, for work last week. Small solder is crucial for chips. Small soldering iron tips are also very nice - especially asymetrical ones that have a tip over to one side. All kinds of surfaces to use.

Tin at least one pad before you put the part on the board. With resistors, put a mound of solder on one pad, put the piece in position, reheat the solder, and use a toothpick to keep it in place. With surface mount chips, tin two corner pads, then reheat one at a time as you press the chip down. Even with one or two pins down, with small legs, you can still move the chip where you want. To check the chip afterwards: test all adjacent pins for continuity (solder bridges), then each pin to the next part it connects to.

And if you have surface mount transistors or LEDs...good luck. The toothpick works wonders because even a tiny magnetic field on a pair of needlenose pliers can pull a 1206 resistor out of place if it's not soldered down.

 

[BPRJam]

Actually, I find it useful to flux the pads on the PCB before I solder the chip on. The flux serves 2 purposes. 1) It is a little sticky so that it keeps the chip in place, and 2) It allows the solder to flow onto the pad better, getting a more accurate solder in a shorter amount of time.

If you choose to use this method, though, make sure you flux only the pads, and not the space in between the pads. I use a toothpick to selectively apply the flux.

Good luck!

BPRJam

 

[fiddler]

Quote:

Don't drink caffeine

Pffffft, what nonsense.

(BTW this new big grin irritates me. bring back the old grin.)

 

[jamont]

I recall seeing a suggestion (forget where) that if the board had been reflowed, all you need to do is flux the pads, put the chip in place and heat the pins. Has anyone tried this?

 

[maczrool]

Quote:

Originally posted by jamont I recall seeing a suggestion (forget where) that if the board had been reflowed, all you need to do is flux the pads, put the chip in place and heat the pins. Has anyone tried this?

Yes, I have tried it, but it didn't seem to produce a satisfactory joint. There doesn't seem to be enough residual solder.

You can always have a custom stencil made ($$$) for your board and print solder paste on for reflow with the parts in place.

Stu

 

[kheldar]

I have done some minor stuff, for IC's i had a peice of safety pin held in an exacto knife handle, bent at the end, with a bit of tape, it was small so as not to obscure my view... works, but takes time...