How to perform Hand Soldering of a 20TSSOP

[eem2am]

hand soldering 0.4

When hand soldering a 20TSSOP such as LT3477 to a PCB, how would you do it?

The pins are just 0.3mm wide and 0.35mm apart.

Link to LT3477 datasheet...

http://cds.linear.com/docs/Datasheet/3477fc.pdf

would you choose an extremely this solder tip and do it pin-by-pin with 0.2mm solder, or would you “blob” solder all the pins together , and then “mop” up the excess with thin solder braid?

 

[FvM]

20-tssop

TSSOP has a medium scale pin pitch, so you don't need extremely fine tools, I think. But even fine pitch down to 0.5 or 0.4 mm is usually soldered pin-by-pin in prototype production, at least if you don't have a suitable solder paste printing or dispensing option.

However, to connect the LT3447 exposed pad, hot air, infrared or hot plate soldering is required, so you may want to use solder paste for this kind of packages generally.

 

[msyrjala]

hand soldering tssop

When hand soldering a 20TSSOP such as LT3477 to a PCB, how would you do it?

I'd use blob'n'mob with plenty of flux. I usually solder these with a hot (385-395 degC) 2.4mm chisel-tip and 0.7mm solder. Sometimes I even get away without
cleaning.

For exposed pad devices in prototyping I usually
put quite large vias, like 0.4-0.7mm under the device. Then I apply flux on the exposed pad, solder the pins and then solder the EP by applying solder and lots of heat on the underside. 2 layer 0.8mm boards are the easiest for this, for thicker boards and more layers (probably large ground planes etc.) a thermal plate will be very useful or necessary.

For prototyping I always use leaded solder, which flows much better.

Also, I like using leaded HASL boards; with some boards you can get good solders by just applying flux and pressing the pins to board with the iron with almost no solder added! In this case you need to solder the EP first and be careful not to move the device while soldering!

 

[siongboon]

Re: Hand Soldering a 20TSSOP

Ya.
I also uses a lot of flux.
The flux enables the solder to become rather liquid,
making it easy to be suck away from the joint.

I am quite surprise about the effect of flux
on the soldering.

Just wet all the pins with flux.
Wet the joint of solder, then suck the unused soldered back
away from the soldering joint.
Put more flux if necessary.

http://www.siongboon.com/projects/2009-04-22_smd_soldering/index.htm#SMD%20soldering%20(prototyping%20PCB%20socket%202.54mm%20pitch)

Best Regards,
Siong Boon