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SMT soldering , lot of questions

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sgrudu

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Hello, I want to know what are the tools I can use to mount SMT IC's
on boards for my personal projects. I'd like to have some information
and opinions based on experience .
Say what you use for your SMT projects of one of few boards.
To be more clear, I say that I want to use TSOP packages and PQF-208
packages.
Looking on elektroda and on the net I see there are 2 possibilities:

1) reflow ovens
2) manual solders

I have questions about both:

1)
- why do they cost so much. It seems to me it is impossible to
find something under $5000 .. What do they do so special other
than making air hot ? :)

- supposing I will have access to a reflow oven in a lab, what
else do I need ? And where and for which prices [I live in Europe] ?
Do I necessarily need to make a stencil ? What do I need to make it ?
Usually what is the material in which stencils are made ?

Which kind of tin and glue should I look for ?


2)
Searching around I've found that some good solders for SMT could
be METCAL and Weller.
Do you have any suggestions ?
I'd like to know some good models of them, the cheapest but
good for the smt packages that I have mentioned.

I've seen there are some models of solders which don't require contact,
they instead work with hot hair... what do you think about them ?


Thank you for your comments!
Sgrudu.
 

direnc

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For your second option, add Antex to your sodering equpment list. See
http://www.antex.co.uk/
They have really innovative , high quality products.
 

loki

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Reflow at work.

If you're not talking super fine pitch smt or BGA, a good soldering iron setup with a fine tip (such as Metcal) and a Binaural microscope can do wonders. Although, the job may be tedious without reflow.

For BGA you will need a reflow system of some sort (metcal has a really cool laboratory one for big bucks 35K). The results of a job for a non-controlled reflow on a BGA may prompt you to get a third party to perform the reflow on those parts for a fee. A third party will generally guarentee the work to be free of voids or shorts. Probably about $100 per BGA, though.

There are small reflow systems available for piecewise work. Results as noted above.

You're best bet if you insist on doing reflow yourself is to get a small reflow oven with temperature profiling abilities. Small bench top ovens are available. Seen them on ebay every now and then.
If you plan on making a bunch of the same PCB this may be a decent solution. On the other hand, in todays economy, you may want to see how much a third party will charge you for small quantity runs.

The stencils I've seen have usually been metal and can be bought through suppliers. I've also seen some disposable ones made of plastic.

If you use a solder paste, be aware that some of them need to be refrigerated and have an expiration date. Don't know why.

Loki
 

loki

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Hand reflow

By the way, the good hand reflow systems have an alignment function using a split-mirror arrangement. This allows you to precisely align chips to the pads on a PCB (including BGA). I wouldn't get one without this feature.

Once again, see Metcal to get an idea of what is offered in terms of hand reflow systems.

Loki.
 

flatulent

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heat oven

If you use a heat oven you may have to get permits from your local fire department and meet many building code requirements. Many commercial companies find these requirements so expensive to meet that they do not use ovens. They use hand soldering for small batches and hire out the large batches.
 

mdamdam

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SMT soldering

I use a simple Ersa Iron caled Micro-con with few tips accessories for less than 1000€ but you have the same at Weller.
I think that the most important is the optical, after many test, the best ( for me ) is Vision Engineering ( Mantis model )
http://www.visioneng.com/mantis/index.htm
With a small air compressor and a foot switch controling a valve, I can easyly dispense solder.
I have soldered many cards with TSSOP, TQFP..... 0805 discrete... with no problems.
Damdam
 

buck

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Hand SMT Soldering

I use Metcal exclusively. They have a wide range of tips and they can be easily change on the fly.

For most IC work I prefer the STTC 122 tip. I have found that it is a good overall tip for IC work. The tip is .025 in (.63 mm) wide and works very well on fine pitch flat packs.

The cost of a Metcal station is high $600 US or more for the low end model but it is well worth it.

:)
 

alledauser

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You don't need anything special to handle the packages you mention.
Just use solder cream and liquid flux. Do not use the solder too much. Use flux genereously. It prevents solder bridges. Heat 1 one 2 pads at a time using a suitable soldering iron. Remove any solder bridges with a solder brite, after finishing with all the pads at one side. Remember you should use very small amount of solder cream..You shall need to use some kind of magnifier, fixed to your workbench somehow. Do some exercises on some cards first. You can use a PCI card for instance. When you feel confident, go ahead with your cards. I used this method for TQFP100 packages successfuly. It is a bit time consuming but works.
Some people can do it with ordinary soldering wires. using the same method to remove the solder bridges. Use at your own risk :)
regards
 

flatulent

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older metcal

The older versions of metcal soldering irons are frequently offered on auction sites at a much lower price than the new price.

Commercial firms find that microscopes specifically designed for SMT work (they have a long arm to keep the base out of the way and have a ring light source) are well worth the $1000 US or so price for employees who do a lot of SMT soldering.
 

DavidP

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I'm working daily with Hakko tools. They are perfect and offer all solutions. The prices are not in the sky.

David
 

stevenyouth

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You can buy the solder about radius 0.25mm and 60%, and the solder iron GOOT,soldering carefully, and you can solding SMT very well.
 

Elvis P.

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All you need beside ultra small and medium tips is a concave tip, which is extremly useful when soldering an IC: put some flux on the PCB, place the IC and all the solder for the IC will be provided by the tip.
Take care that u use a water based flux which you can wash away.
(Your print won't be that sticky *gg*)

Regards Elvis
 

toonafishy

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I like the Metcals but >>$$. I can also use Weller WES50 with very fine tips <<$$. Lately, I've been soldering BCC+ and QFN where the pads are under the package and inaccesable from the top. I put solder on all package pins and then wick it off with Solder-Wik. I do the same on the board. Then apply some flux. Place the package on the board and hold it down with a wooden toothpick. I then reflow the part with a heat gun. This work is easier if you have a paste stencil so you can apply paste and not have to go throught the tinning process.
 

jzaghal

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HAKKO for SMD !!

Yes,

I agree Hakko station for smd work is the best. You initially need
the main station, squeeze the bit you get with it, and you can do
all sorts of soldering and desoldering of the most common cases upto
QFP44.

Bye.
 

mdamdam

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I agree with Elvis .
The concave tip is VERY usefull for ICs. You can use with every Iron , it is cheap and have the avdantage of giving just the good qantity of solder. A fine tip is valid for discretes and transistor....
For removing ICs: here is my own low cost solution:
Dispose solder paste on every ICs pins.
Then you use a heat gun like those used for shrink tubing. When you see the solder is fluid, it is ok to remove the ICs asap.
( Use any tool... small cutter under the IC for example ) .
Clean the solder and flux ( flux remover ).

M
 

sgrudu

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so it seems that for PQF-208 packages I should forget manual soldering :cry: , right ?

Nobody talked about stencils... are they usually given by the pcb manufacturer ?


Thank you for all your replies !
 

alledauser

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As far as I know, stencils are not usually given by the PCB manufacturer.
When you go to a assembly facility, they charge you some cost which includes stencils, configuring machines etc.
Anyway, with fine pitch packages and manual soldering, stencils are useless. You usually don't have solder stops between the pads even with machine mounting.
regards
 

fakhry2002

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dont forget about manual soldering for PQF-208 packages
i made an fpga board for myself, using spartan 2 - 200kgates , which use the PQF-208 package
and the soldering was done manual with an iron with a very narrow tip, (dont know dimensions of it)
and it works perfect :)
 

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