# SMT soldering

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#### notbob

Jan 1, 1970
0
I have zero experience with SMT soldering. I have a Weller WTCPS
soldering station. Is there a tip that is good for SMT soldering or
should I get a different model station?

nb

S

#### Simoc

Jan 1, 1970
0
You don't need anything more than a sharp tip. The smaller the better,
but as considering your zero-experience, I don't think that you are
going to solder the smallest and the most difficult components on a PCB
with the highest component/surface -density, so I'm pretty sure that
any sharp tip will do

N

#### notbob

Jan 1, 1970
0
with the highest component/surface -density, so I'm pretty sure that
any sharp tip will do

I guess my real concern is temperatures. The WTCPS station is a
regulated power supply with changeable fixed temp tips. The lowest
tip temp I've been able to find for it is 600 deg F. From what little
I've been able to find on SMT solder temps on the web, it appears most
SMT work is sub-500 deg F, making my station a bit hot. Will my
station be ok if used with a judicious touch? I may have no
experience with SMDs, but have more soldering experience than I care
to relate.

nb

P

#### phaeton

Jan 1, 1970
0
notbob said:
I guess my real concern is temperatures. The WTCPS station is a
regulated power supply with changeable fixed temp tips. The lowest
tip temp I've been able to find for it is 600 deg F. From what little
I've been able to find on SMT solder temps on the web, it appears most
SMT work is sub-500 deg F, making my station a bit hot. Will my
station be ok if used with a judicious touch? I may have no
experience with SMDs, but have more soldering experience than I care
to relate.

nb

I always thought most guys used solder paste and a hideous $4.99 toaster oven they bought at the local GoodWill or Starvation Army. When doing SMT stuff. -phaeton N #### notbob Jan 1, 1970 0 I always thought most guys used solder paste and a hideous$4.99
toaster oven they bought at the local GoodWill or Starvation Army.

yeah, I got that page bookmarked, too.

nb

N

#### notbob

Jan 1, 1970
0

Lotta good info in that thread. Thanks.

nb

D

#### David L. Jones

Jan 1, 1970
0
Simoc said:
You don't need anything more than a sharp tip. The smaller the better,
but as considering your zero-experience, I don't think that you are
going to solder the smallest and the most difficult components on a PCB
with the highest component/surface -density, so I'm pretty sure that
any sharp tip will do

No actually. You need a small wedge shape tip that gets good contact
with the pad and component, sharp conical tips are not very good for
this.
The rest is pad layout, technique, and 0.46mm or finer solder. A pair
of tweezers is absolutely essential, I prefer the straight sharp
pointed type, but the angled type can be handy too.

Re. pad layout. If you are designing a board for hand soldering then
you have to have larger pads that allow surface area for the tip. It's
much more difficult to hand solder "high density" pads that have little
or no oversize. The recommended IPC footprints are large and are good
for hand soldering, but crap for high density production layouts.

Dave

P

#### phaeton

Jan 1, 1970
0
notbob said:
yeah, I got that page bookmarked, too.

nb

I don't, but a lot of guys in an IRC channel I haunt periodically do
just that. A few of them build SMT boards exclusively.

It's probably a bit too much fine detail for me. CTS/Tendonitis and
all makes me a little 'clumsy' in the hands, and the eyes aren't the
20/10 that they used to be. I plan on giving it a shot sometime down
the road, but for now I'm still getting better at soldering
through-hole stuff.

-phaeton

S

#### Simoc

Jan 1, 1970
0
David said:
No actually. You need a small wedge shape tip that gets good contact
with the pad and component, sharp conical tips are not very good for
this.

OK, I agree, but by putting a little solder to the bit before
begionning to heat the component and the pad, both will get heated, and
sharp bit will do...but of course, in case of more advanced work, some
kind of more advanced tool will do better

M

#### Melodolic

Jan 1, 1970
0
Simoc said:
OK, I agree, but by putting a little solder to the bit before
begionning to heat the component and the pad, both will get heated,
and sharp bit will do...but of course, in case of more advanced work,
some kind of more advanced tool will do better

I put a little touch of solder on one pad, and then slide the component onto
it while heating with the tip of the iron (fine tweezers and wedge shaped
bit!). The part slides into a little pool of solder and can be positioned
before withdrawing the iron. With the part tacked in place, I then do the
other end normally, using just iron and solder, before redoing the first
joint with iron and solder.

Can't say I've found pointy tips to work reliably - hard to get the heat in
fast enough. Maybe they're okay for 0603 size?

D

#### David L. Jones

Jan 1, 1970
0
Simoc said:
OK, I agree, but by putting a little solder to the bit before
begionning to heat the component and the pad, both will get heated, and
sharp bit will do...but of course, in case of more advanced work, some
kind of more advanced tool will do better

A wedge shaped tip is hardly a more advanced tool!, it's the right tool
for the job. Better for normal soldering too. Conical tips are pretty
much useless for normal and SMD soldering.

Dave

D

#### David L. Jones

Jan 1, 1970
0
Melodolic said:
I put a little touch of solder on one pad, and then slide the component onto
it while heating with the tip of the iron (fine tweezers and wedge shaped
bit!). The part slides into a little pool of solder and can be positioned
before withdrawing the iron. With the part tacked in place, I then do the
other end normally, using just iron and solder, before redoing the first
joint with iron and solder.

Yeah, that's one of the standard techniques, and works very well.

Dave

S

#### Simoc

Jan 1, 1970
0
David said:
A wedge shaped tip is hardly a more advanced tool!, it's the right tool
for the job.

"Righter" for the job --> more "advanced" to the job, isn't it?
Better for normal soldering too. Conical tips are pretty
much useless for normal and SMD soldering.

Agreed, and good if the OP has better tip for doing, but my points were
originally just that
a) If the OP has just a tip that is non-sharp and is too big, it won't
do.
b) If he has a sharp tip, it will probably do, even if it's quite big.
c) I would think that soldering irons/stations have more often as
original tip either a sharp tip or a one that is not suitable for this
job, than a correct-sized wedge-shaped one.

M

#### Melodolic

Jan 1, 1970
0
Simoc said:
Agreed, and good if the OP has better tip for doing, but my points
were originally just that
a) If the OP has just a tip that is non-sharp and is too big, it won't
do.
b) If he has a sharp tip, it will probably do, even if it's quite big.
c) I would think that soldering irons/stations have more often as
original tip either a sharp tip or a one that is not suitable for this
job, than a correct-sized wedge-shaped one.

I think the idea is to go to the wedge-shaped bit shop and buy one.

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