Electronics > Manufacturing & Assembly

Best way to solder a TSSOP20?

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Faringdon:
Hi,
Just developed a new way to solder TSSOP20..eg UCC28070A. (0.65mm pitch)
I have never seen this on youtube, or anywhere...

Does not use...
1....Hot air
2....Hot plate
3....Braid (no mopping up with braid and getting braid stuck to several pins)

Just uses a (pref regulated) soldering iron with a pointed tip, approx 0.5mm,  and a bit of flux on the pads to start off. And some brass wool to wipe the excess  solder off repeatedly.

Just uses the principle that solder is attracted to the hotter surface.

First tack down the four corner pins, 1 then 11, then 20, then 10 (go diagonally)

Then simply give each pin a generous soldering.
Dont worry about shorted pins.

Then simply turn the soldering tip to that temperature which tends to attract molten solder off the shorted regions to the tip, and literally kind of pull the solder off  the shorted bits and wipe it off in brass wool, repeatedly.
Try and motion the tip between the pins so it pulls the solder short out.
If the solder short wont move , then tease it fom pin to pin till its  at the edge pin.......when its there, its easy to pull it out by kind of pulling toward the edge with the solder tip. (at the edge, theres no adjacent pin for it to short to)
For some reason its easy to pull the short  "sideways" from an edge pin...and when you do that, you unshort the edge pin.
Alternatively, and this is usually not needed...just use a tiny pinpoint of braid to unshort this last edge pin short.

The secret is in getting the tip to that temperature which is hot enough to pull off the solder from the shorted bits...pulling it off onto the iron, where you wipe it off on brass wool.

Does anyone have any enhancements for this.....eg better tip shapes for it etc?

jpanhalt:
Congratulations on success.  Your method  is not a lot different than the drag method with solder braid.  But hopefully, some will find it useful.  My concern with wiping with brass wool is that unless it is quite fine, you run the risk of pulling a pin off its pad.

I use the  drag method with solder wick.  Even then, a light touch is needed.

Faringdon:
Thanks, just in case i explained wrong, i wipe the solder tip in brass wool, not the soldered pins.......when i "dab" the solder iron to extract the short, it is ensured the iron is hot enough so that it doesnt pull the pin and "break" it.....

retiredfeline:
Same as you I tack down the corners, then I apply solder paste sparingly to the legs, but not the knees. I then swipe a chisel tip in a diagonal outward motion to melt the paste.

zzattack:
Only solder 2 corners instead of 4. There's always too much solder on a single pin if you do it manually, which leads to higher chance of bridging there. Then begin soldering from the other side (so tack pin 1, start soldering at pin 10 in your example).
With good flux, consistent travel speed and very light pressure from the iron, the solder should follow the tip nicely and it's very possible to not have any bridges in the first place. If bridges do form, using a hoof-/reservoir-style tip makes it very easy to solve them because the reservoir has nearly a suctioning kind of pull.

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