Air pencils for SMT soldering?

[Richard]

Are air pencils really a lot easier for SMT assembly? Are there
drawbacks, besides the cost? Recommendations for a good system?

I've seen impressive demos using QFP packages, but I've also heard
frustrations about passives getting blown off the board. (I've also
read that ceramic chip caps shouldn't be iron-soldered because of the
thermal stress.)

Metcal offers a model, and Zephyrtronics does an impressive demo at
shows - any comments on these?
http://www.metcal.com/products/hotair_pencil.htm
http://www.zeph.com/pencil.html


Pre-heaters seem like a great idea - are they practical, or a gimmick?
http://www.zeph.com/airbathseries.htm

Thanks,
Richard

 

[Paul Burke]

Richard wrote:

Are air pencils really a lot easier for SMT assembly? Are there
drawbacks, besides the cost? Recommendations for a good system?

I've seen impressive demos using QFP packages, but I've also heard
frustrations about passives getting blown off the board. (I've also
read that ceramic chip caps shouldn't be iron-soldered because of the
thermal stress.)

I've found them totally useless. Maybe it's just my technique, but for
the small quantities I do (i.e. prototypes) the soldering iron has
proved the best bet, with a wavetip for QFPs and TSSOPs.

Paul Burke

 

[Winfield Hill]

Paul Burke wrote...

Richard wrote:
Are air pencils really a lot easier for SMT assembly? Are there
drawbacks, besides the cost? Recommendations for a good system?

I've seen impressive demos using QFP packages, but I've also heard
frustrations about passives getting blown off the board. (I've also
read that ceramic chip caps shouldn't be iron-soldered because of the
thermal stress.)

I've found them totally useless. Maybe it's just my technique, but
for the small quantities I do (i.e. prototypes) the soldering iron
has proved the best bet, with a wavetip for QFPs and TSSOPs.

We got a Zephyrtronics last June, and love it, especially for the
really small stuff. You can turn down the air pressure to suit.


--
Thanks,
- Win

 

[Dave Garnett]

"Paul Burke" <paul@scazon.com> wrote in message
news:310v9lF32fs3fU1@uni-berlin.de...

Richard wrote:
Are air pencils really a lot easier for SMT assembly? Are there
drawbacks, besides the cost? Recommendations for a good system?

I've seen impressive demos using QFP packages, but I've also heard
frustrations about passives getting blown off the board. (I've also
read that ceramic chip caps shouldn't be iron-soldered because of the
thermal stress.)


I've found them totally useless. Maybe it's just my technique, but for the
small quantities I do (i.e. prototypes) the soldering iron has proved the
best bet, with a wavetip for QFPs and TSSOPs.

Paul Burke

I agree. You are supposed to use air pencils with a hotplate to get
everything pretty warm first, but since I have components both sides, this
doesn't really work ...

De-soldering is another game entirely

Dave



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[Richard]

Winfield Hill wrote:

We got a Zephyrtronics last June, and love it,
especially for the really small stuff. You can
turn down the air pressure to suit.

Good feedback, thanks. Can it be set low enough to do 0402's without
holding them in place?

Anything special about the Zephyr unit vs. others, or just positive
results moving to an air pencil in general? (I like that it's core to
their product line vs. other vendors' treatment of their air pencils.)

Thanks!

 

[Richard]

Dave Garnett wrote:

You are supposed to use air pencils with a hotplate
to get everything pretty warm first, but since I
have components both sides, this doesn't really work

?? Because the hot plate would touch the bottom-side components, or
because they'd de-solder? (But solder shouldn't melt at the 150c
pre-heat temp...)

I've seen some (e.g., Metcal's) that are a flat hot element that I guess
you'd set the PCB onto, but an air-based unit would seem to make more
sense with bottom-mounted parts.

A lot of our bypass caps end up on the bottom, so I'm curious if you ran
into a particular problem.

Thanks!

 

[Richard]

mike wrote:

This is the cheapest thing I found that looked decent.
http://www.mpja.com/directview.asp?product=+15159+TL&Go.x=14&Go.y=7&Go=direct

Slick, if even just for bulk removal work. I wonder how low the CFM
goes.

 

[nospam]

mike <spamme0@netscape.net> wrote:

By accident, I discovered that a Weller Portasol Butane soldering iron
with the catalytic hot air tip works wonderfully for small jobs.
Air flow is almost zero and there's a lot of IR going on too.

And what comes out doesn't contain much oxygen so it doesn't oxidise the
solder. It might even contain a bit of carbon monoxide to reduce it?

 

[Winfield Hill]

Richard wrote...

Winfield Hill wrote:
We got a Zephyrtronics last June, and love it,
especially for the really small stuff. You can
turn down the air pressure to suit.

Good feedback, thanks. Can it be set low enough to do 0402's without
holding them in place?

Not sure. I usually have some 2nd-hand activity.

Anything special about the Zephyr unit vs. others, or just positive
results moving to an air pencil in general? (I like that it's core to
their product line vs. other vendors' treatment of their air pencils.)

Not familiar with the others, but the frame and under-heat setup of
the is Zephyrtronics is very nice. We modified it a bit to take into
account our smaller boards. Intended for prototype work of course.


--
Thanks,
- Win

 

[Paul Burke]

Spehro Pefhany wrote:

It's hard to prototype QFN and other packages that have no leads
protruding (eg. some SMT inductors) without hot air.

Yes, I've only limited experience with QFN. What I did there (just for
the prototype, the great thing about PCB Pool is that you KNOW you've
got to pay for the phototools again, so a few specials just for the
prototype don't matter) was to make a hole - for a larger QFN I'd use
more than one- in through to the underside pad, large enough to get the
tip of a fine iron right through. Solder the component on "as usual"
(hard with such little pads on the side, but possible), then flood the
undeside with solder. Worked pretty well.

Paul Burke

 

[Ken Smith]

In article <41AB3F2B.DFAF89F8@no.spam>, Richard <rh86@no.spam> wrote:

Are air pencils really a lot easier for SMT assembly? Are there
drawbacks, besides the cost? Recommendations for a good system?

I've seen impressive demos using QFP packages, but I've also heard
frustrations about passives getting blown off the board. (I've also
read that ceramic chip caps shouldn't be iron-soldered because of the
thermal stress.)

Metcal offers a model, and Zephyrtronics does an impressive demo at
shows - any comments on these?

I like the Zephyrtronics pre-heater. The desoldering stuff that comes
with it is very easy to use and leaves the PCB un damaged.

The hot-air-soldering pencil is the easiest way to solder the TQFP
packages. You put on the paste place the chip, preheat the PCB and then
go around the part with the hot air. If you use only modest amounts of
paste, there is virtually never a solder bridge. Every pin gets soldered.

Soldering SMT film caps is a job that must be left to the experts.
Ceramic capacitors can be soldered with an iron if you are careful but it
is not recomended for thermal stress reasons. Use the coolest most
thermally conductive tip you can and ideally pre-heat the PCB if you are
using an iron.

On proto-types I often solder parts with a metcal. 0402 components are
about as small as is practical for manual work. If you are working on
stuff this small, you have to have non-magnetic tools. Even a slightly
magnetized tool will pick up an 0402 part.


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