"zindazenda" wrote in message
...
can anyone recommend at diy way of flow soldering surface mount
components??
i ask as making somr boards up that are totally sm, and well i am going
blind trying to solder them using iron!!

thanks g0zen..


Here is a link for the "Ez-bake" approach to soldering.

http://www.seattlerobotics.org/encod...6/oven_art.htm

gb

What I have done in the past is to tin the pads where the parts are going
to be mounted and then I use two soldering irons. One on each pad and it
pulls the part right down into a good position.

Ok ok I hear the question now. What about parts with more than two leads?

That is a valid and good question. Only tin two pads for that part and use
the soldering iron on each one of the pads to get the part mounted and in
position to finish soldering the rest of the leads one at a time.

no..on investugation this looks well abit crap..i cant see how it is going
to work with 100 sm 0805 components..
so anyother ideas..
can one buy flow soldering equipment s/h???
g0zen..
"Allan Butler" wrote in message
news:ALRjc.5600$Rd4.566539@attbi_s51...
What I have done in the past is to tin the pads where the parts are going
to be mounted and then I use two soldering irons. One on each pad and it
pulls the part right down into a good position.

Ok ok I hear the question now. What about parts with more than two leads?

That is a valid and good question. Only tin two pads for that part and
use
the soldering iron on each one of the pads to get the part mounted and in
position to finish soldering the rest of the leads one at a time.

"zindazenda" wrote in message
...
"Allan Butler" wrote in message
news:ALRjc.5600$Rd4.566539@attbi_s51...
What I have done in the past is to tin the pads where the parts are
going
to be mounted and then I use two soldering irons. One on each pad and
it
pulls the part right down into a good position.

Ok ok I hear the question now. What about parts with more than two
leads?

That is a valid and good question. Only tin two pads for that part and
use
the soldering iron on each one of the pads to get the part mounted and
in
position to finish soldering the rest of the leads one at a time.

no..on investugation this looks well abit crap..i cant see how it is going
to work with 100 sm 0805 components..
so anyother ideas..
can one buy flow soldering equipment s/h???
g0zen..

Actually, for the occasional prototype, the two-iron method, while a bit
tedious, works. (and while 0402 parts are a bit of a bear, even with my
aging vision I can handle 0805's and 0603's with this method ... but it
takes time and patience and I don't like to do a *lot* of parts that way)

You can also, with a bit of practice and care, use a "heat gun" to reflow
boards if you don't envision doing enough of it to justify the cost of
"real" reflow equipment.

I purchased a very nice and effective hot-air system for about $350 new on
e-bay (search on "reflow" - the brand I bought is "ATTEN" and it's
distributed by a company called "smtpros" if I recall correctly) ... and
I've also purchased a toaster oven for the "ez-bake" method ... do a search
on Google or Yahoo and you will find a Yahoo group on "ez-bake" with a long
thread of useful and informative discussion and hints.

Remember, for reflow you need solder *paste* ... available from a number of
sources on the web. I prefer the "no clean flux" kind, though I usually
clean the boards afterwards anyway ...

73,
Carl - wk3c

zindazenda wrote:

no..on investugation this looks well abit crap..i cant see how it is going
to work with 100 sm 0805 components..
so anyother ideas..
can one buy flow soldering equipment s/h???
g0zen..


Sir:

From necessity I did this with well over 500 parts on two assemblies for
radios that were prototypes. The people that had tried to do the assembly
with the approved methods had set the solder paste on the pads, placed the
parts in postion, both steps done by hand and then washed the boards
before they vapor phased the boards. This department then went ahead and
cleaned the filters out of the washing equipment, repasted the boards and
just put the parts where they fit.

I got two blank boards and all the parts sorted out into envelopes in tote
pans with clean prints of the parts list and a component layout with the
task set to get it done in a certain amount of time.

Monday through Saturday I worked 16 hour days and then on Sunday I took it
easy and worked 12 hours.

In addition to the surface mount parts I also had about the same number of
leaded parts on each board.

When I was done I was told that there were a total of 5 errors between the
two boards. It took about 2 to 3 weeks to accomplish this and several sets
of batteries for headset radio.

There were times I would place parts on the bench in front of me, put the
envelope back into the tote pan and could not see the parts. I would find
them after blinking several times, place them and then get up to take a
walk through the area to get things loosened up and relaxed a little bit.

This method I described is indeed a possible method. It has been done by
others than myself and sometimes it is the most expedient method to
accomplish the task.

The smallest parts available would make this method a challenge but it would
still be something that could be done with some time and paitence.

Good luck on your project and I wish you the best Sir.

zindazenda wrote:
no..on investugation this looks well abit crap..i cant see how it is going
to work with 100 sm 0805 components..
so anyother ideas..
can one buy flow soldering equipment s/h???
g0zen..
"Allan Butler" wrote in message
news:ALRjc.5600$Rd4.566539@attbi_s51...
What I have done in the past is to tin the pads where the parts are going
to be mounted and then I use two soldering irons. One on each pad and it
pulls the part right down into a good position.

Ok ok I hear the question now. What about parts with more than two leads?

That is a valid and good question. Only tin two pads for that part and
use
the soldering iron on each one of the pads to get the part mounted and in
position to finish soldering the rest of the leads one at a time.



For many irons, you can also buy fork-ended solder tips that bridge over
the parts. I made one by cutting and filing an old tip, and it worked OK
for parts removal. However, it would need some co-ordination to make the
tip contact the two pads without also knocking the part out of place.

The toaster oven looks like a much better method for a whole-board
assembly project, except for two key problems:

1. Solder paste is expensive

2. Solder paste doesn't keep (seems to have about the same time constant
as Horowitz & Hill's wet fish)

Those are big problems for occasional, low-volume users such as
ourselves. So the questions a

1. Where's a low-cost source of solder paste? (in various parts of the
world)

2. How can we either store it so it stays fresh; or re-constitute it
after it's gorn orf?


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)

http://www.ifwtech.co.uk/g3sek

"Ian White, G3SEK" wrote in message
...




2. How can we either store it so it stays fresh; or re-constitute it
after it's gorn orf?

It keeps much better if it is kept in a fridge.


Leon
--
Leon Heller, G1HSM
http://www.geocities.com/leon_heller

2. How can we either store it so it stays fresh; or re-constitute it
after it's gorn orf?

It keeps much better if it is kept in a fridge.

Try the freezer - lasts MUCH longer. That's where I keep mine. It only takes
a few minutes to defrost (good conductor) and keeps for years, even with the
occasional defrosting.

BR H

2. How can we either store it so it stays fresh; or re-constitute it
after it's gorn orf?

It keeps much better if it is kept in a fridge.

Try the freezer - lasts MUCH longer. That's where I keep mine. It only takes
a few minutes to defrost (good conductor) and keeps for years, even with the
occasional defrosting.

BR H

"Ian White, G3SEK" wrote in message
...

2. Solder paste doesn't keep (seems to have about the same time constant
as Horowitz & Hill's wet fish)

2. How can we either store it so it stays fresh; or re-constitute it
after it's gorn orf?

Solder paste must be kept refrigerated to maximize its shelf life. (read the
manufacturer's storage and handling instructions CAREFULLY, both for proper
storage for product longevity and for safety reasons)

Note: If you don't have a dedicated refrigerator and *must* use one you
keep food in, you *must* take the *utmost* of care to do (at least) the
following
before even *considering* putting solder paste in your (regular, food
storage) refrigerator (and you should probably do this even if you have a
dedicated refrigerator):

1) clean the tube VERY well after use to make sure no paste is on the
outside
2) place the tube in a plastic "zip-lock" bag (which must not be
contaminated with solder paste)
3) place the bag, with the tube inside into a plastic container with a
tightly sealing lid (again, this must be clean and not contaminated with
solder paste)

Doing this *very carefully and meticulously* will at least minimize the
possibility of contaminating your refrigerator with solder paste particles,
which are VERY small ...

Further notes: You should, at after each step above, THOROUGHLY wash your
hands to assure that you don't transfer any solder paste to the outside of
the bag or the plastic container. Use a fresh, brand new bag each time
(they are cheap). Also wash the plastic container THOROUGHLY inside and out
each time you prepare to re-store your solder paste (don't wash it in your
dishwasher - do it manually and clean up afterwards as if you were cleaning
up a hazmat spill). And finally, NEVER use the plastic container for food
after you've stored solder paste in it, NOT MATTER HOW WELL YOU THINK YOU'VE
CLEANED IT.

Ultimate note: If you have children in the home who could get into the
refrigerator and get at the solder paste, you probably shouldn't even
consider putting solder paste in your refrigerator where the children could
get at it ...

DISCLAIMER: While I believe the precautions above to be adequate and use
them myself, I take no responsibility for any consequences of a proper lack
of care on anyone's part in doing what I describe above, or any inadequacy
in my suggestions. Anyone following these suggestions does so solely at
their own risk.

73,
Carl - wk3c

p.s. Additionally, anyone considering the "ez-bake" method of reflow
soldering needs to understand the ABSOLUTE necessity of having a dedicated
toaster oven that is NEVER used for food preparation. It, along with all
soldering supplies should be used and stored in an area that is inaccessable
to children (keeping in mind how inquisitive children are and their ability
to get into things that you *thought* were secure or inaccessable).