Homemade SMD prototyping - with hot air

[Robert Scott]

I have seen various postings about doing SMD prototyping with very
fine point irons and solder wick for cleanup, but I would like to try
hot air. But I don’t want to invest in a several $k professional hot
air SMD rework station. I just want to stick down a few SOIC-8
packages. I occurred to me that something like a heat gun might work
if the air flow rate were drastically reduced and the heating element
power were controlled down to an level to produce 700 degree F air,
and if a nozzle could be designed that squired out air in a little
slit. In fact, forget about the heat gun. Just consider a length of
nichrome wire, a controlled current, and a tiny fan. Has anyone tried
to make their own SMD hot air tool for experimental use?


-Robert Scott
Ypsilanti, Michigan

 

[Si Ballenger]

I have seen various postings about doing SMD prototyping with very
fine point irons and solder wick for cleanup, but I would like to try
hot air. But I don’t want to invest in a several $k professional hot
air SMD rework station. I just want to stick down a few SOIC-8
packages. I occurred to me that something like a heat gun might work
if the air flow rate were drastically reduced and the heating element
power were controlled down to an level to produce 700 degree F air,
and if a nozzle could be designed that squired out air in a little
slit. In fact, forget about the heat gun. Just consider a length of
nichrome wire, a controlled current, and a tiny fan. Has anyone tried
to make their own SMD hot air tool for experimental use?

I think most cheap DIY setups are based on the Radio Shack
desoldering iron (part 64-2060). The general approach is to
remove the rubber bulb, and replace it with a source of air, such
as a piece of aquarium air line tubing you can gently blow into
to force air out the tip. The tip is stuffed with some fine steel
wool which absorbs heat from the tip and helps heat the air
moving through and out the tip to the solder surface.

 

[mike]

I have seen various postings about doing SMD prototyping with very
fine point irons and solder wick for cleanup, but I would like to try
hot air. But I don’t want to invest in a several $k professional hot
air SMD rework station. I just want to stick down a few SOIC-8
packages. I occurred to me that something like a heat gun might work
if the air flow rate were drastically reduced and the heating element
power were controlled down to an level to produce 700 degree F air,
and if a nozzle could be designed that squired out air in a little
slit. In fact, forget about the heat gun. Just consider a length of
nichrome wire, a controlled current, and a tiny fan. Has anyone tried
to make their own SMD hot air tool for experimental use?


-Robert Scott
Ypsilanti, Michigan

Cheap hot air guns designed for paint stripping can work well.
Get the variable heat model if you can. The thermal part is open loop
so dependent on air flow.
The air flow is high, so there's risk of blowing the parts off the board.
You can use a smaller tube do direct a portion of the air flow to the
work and divert the rest. You can't just restrict the air because
you'll blow the thermal fuse.

For small chips, just waving the heat around works well. For bigger
chips, it's helpful to form a rectangular opening and put in a baffle so
the air goes around the leadframe area only.

I just tripped over some Leister hot air wands. Having precise
temperature control makes life much easier. Now I'm trying to cobble
the thing onto a Dirt Devil Vacuum cleaner as an air source. 10 feet
of hose with a wire down the middle results in a lot of back pressure.
mike


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[Brian]

Cheap hot air guns designed for paint stripping can work well.
Get the variable heat model if you can. The thermal part is open loop
so dependent on air flow.
The air flow is high, so there's risk of blowing the parts off the board.
You can use a smaller tube do direct a portion of the air flow to the work
and divert the rest. You can't just restrict the air because you'll blow
the thermal fuse.

For small chips, just waving the heat around works well. For bigger
chips, it's helpful to form a rectangular opening and put in a baffle so
the air goes around the leadframe area only.

I just tripped over some Leister hot air wands. Having precise
temperature control makes life much easier. Now I'm trying to cobble
the thing onto a Dirt Devil Vacuum cleaner as an air source. 10 feet
of hose with a wire down the middle results in a lot of back pressure.
mike


--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
.
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
Wanted TEK SG504, don't need the head.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

You must all be hobbiests, I assume? Heck, we end up with quite a bit of
protowork here. I'll admit, while to our good customers we almost give it
away, it can be expensive as a "one-off". But then again, if your time is
worth something and you want it done well, perhaps it is cheap afterall.

Brian - http://www.risingtechnologies.net

 

[Robert Scott]

You must all be hobbiests, I assume? Heck, we end up with quite a bit of
protowork here. I'll admit, while to our good customers we almost give it
away, it can be expensive as a "one-off". But then again, if your time is
worth something and you want it done well, perhaps it is cheap afterall.

Brian - http://www.risingtechnologies.net

Actually I am a bit more than a hobbyist. I do embedded systems
design, mostly software, and occasionally do some board design and
prototype building. It would take me more time to explain to a
contract assembly house such as yours what I want done than to do it
myself. (Think of quantity 2 boards.) However if I ever wanted to
make more than about 8 boards of the same type I would definitely
consider a contract manufacturer.

After having posted the original question, I now see that I was wrong
in assuming that all hot air SMD prototyping stations were in the
multi $k range. I found some systems for under $300 plus a little
more for optional nozzles from Xeltek. Anyone have any experience
with this company?


-Robert Scott
Ypsilanti, Michigan

 

[mike]

Actually I am a bit more than a hobbyist. I do embedded systems
design, mostly software, and occasionally do some board design and
prototype building. It would take me more time to explain to a
contract assembly house such as yours what I want done than to do it
myself. (Think of quantity 2 boards.) However if I ever wanted to
make more than about 8 boards of the same type I would definitely
consider a contract manufacturer.

After having posted the original question, I now see that I was wrong
in assuming that all hot air SMD prototyping stations were in the
multi $k range. I found some systems for under $300 plus a little
more for optional nozzles from Xeltek. Anyone have any experience
with this company?


-Robert Scott
Ypsilanti, Michigan

This is the cheapest hot air gun I've found.
http://www.mpja.com/directview.asp?product=15159+TL
no experience with it tho.
mike

--
Return address is VALID but some sites block emails
with links. Delete this sig when replying.
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted, 12.1" LCD for Gateway Solo 5300. Samsung LT121SU-121
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

 

[Rich Grise]

You must all be hobbiests, I assume?

Nah. I'm only hobby; John Larkin and John Fields are hobbier, but Watson
A. Name is the hobbiest of us all!

It's "hobbyist".

Cheers!
Rich

 

[Brian]

Actually I am a bit more than a hobbyist. I do embedded systems
design, mostly software, and occasionally do some board design and
prototype building. It would take me more time to explain to a
contract assembly house such as yours what I want done than to do it
myself. (Think of quantity 2 boards.) However if I ever wanted to
make more than about 8 boards of the same type I would definitely
consider a contract manufacturer.

After having posted the original question, I now see that I was wrong
in assuming that all hot air SMD prototyping stations were in the
multi $k range. I found some systems for under $300 plus a little
more for optional nozzles from Xeltek. Anyone have any experience
with this company?


-Robert Scott
Ypsilanti, Michigan

Unless you do something really ODDBALL, a BOM and silkcreen usually
suffices. I have seen designers that have ZERO documentation, in those cases
we really can't help much w/o the bill getting bigger quite rapidly.

 

[Brian]

Nah. I'm only hobby; John Larkin and John Fields are hobbier, but Watson
A. Name is the hobbiest of us all!

It's "hobbyist".

Cheers!
Rich

I am always impressd with those that correct my typos. Wow.

 

[keith]

You must all be hobbiests, I assume? Heck, we end up with quite a bit of
protowork here. I'll admit, while to our good customers we almost give it
away, it can be expensive as a "one-off". But then again, if your time is
worth something and you want it done well, perhaps it is cheap afterall.

Who is "we"? Yes, I've had stuff done by the biggies for what I
considered cheap-money. Though I don't think they were doing me any major
favors (contracted, perhaps). It was clear from the outset that they they
were only going to build them in the single digets, with no repeat
business.

 

[Rich Grise]

I am always impressd with those that correct my typos. Wow.

It's a gift. Or a curse, depending on your POV.
(in either case, please don't be too impressed -you'll find it quite
annoying after a while. Ask anybody! ;-) )

Thanks,
Rich

 

[Richard H.]

After having posted the original question, I now see that I was wrong
in assuming that all hot air SMD prototyping stations were in the
multi $k range. I found some systems for under $300 plus a little
more for optional nozzles from Xeltek. Anyone have any experience
with this company?

Having bought one recently, I'm a big fan of the system at
http://www.zeph.com. It looks like eBay has them occasionally for 10
cents on the dollar, which puts it in the range of a one-man shop.

The air pre-heater makes a big difference, especially with ground
planes. Works like magic on 0402's and 0.5mm leadframes alike.

 

[Robert Scott]

Having bought one recently, I'm a big fan of the system at
http://www.zeph.com. It looks like eBay has them occasionally for 10
cents on the dollar...

If it's that common to find them on eBay selling for such a loss, I
have to wonder why the original owners were so anxious to get rid of
them.


-Robert Scott
Ypsilanti, Michigan