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NOW: SMT not so bad WAS: Re: IRDA repeater
SMT really isn't as daunting as it first looks! You can solder IC's of that
pitch fairly easily with a standard antex 15W iron with the finest bit
fitted.
The main problem for you would be, can you etch the pad lands for the IC
accurately enough on the PCB?
If so, the battle's half won.
What you need:
A pair of angled tweezers
VERY fine solder (0.4MM low residue)
Liquid flux
solder braid
one of them gooseneck magnifiers with lamp buit in (if your eyes aren't up
to it)
First tin the PCB pad lands. Using the braid and liquid flux, remove all
traces of solder from the lands so they are silver but with no bumps of
solder on them.
Now Using the magnifier and tweezers, line up the IC on the lands. Once
lined up, press down firmly on the body of the IC with the tweezers, to
hold
it in place. Dab one side of the IC with liquid flux. Wet the iron with
almost NO solder. Touch the iron on the first pin on the IC. The liquid
flux
should draw traces of solder of the iron's bit and the PCB land to make a
joint between the two...If not add a trace more solder to the iron tip and
a
touch more flux to the IC and try again.
Do the same with the diagonally opposite pin. You can now remove the
tweezers and solder up the rest of the pins using the same method. If you
manage to get a solder bridge between two (or More!) pins, use the braid
soaked in liquid flux to remove....
The key is the liquid flux! I don't know if this is available to buy from
the likes of maplin / RS etc. We use it in work for SMT rework and It's
sprayed onto PCB's just before they enter the flow solder baths on a
production line.
If you were really stuck for flux, I might be able to acquire a small
amount
for you from work ;-) .... or maybe a small donation to one of our repair
guys beer funds would tempt him to solder them on for you during his break!
(depends on numbers really...I wouldn't want me or him getting into
trouble)
Neil
----- Original Message -----
From: "Ian B" <Ian@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Saturday, January 12, 2002 10:20 AM
Subject: RE: [ukha_d] IRDA repeater
As a solution for those with an IRDA repeater problem maybe the relatively
high cost over a production unit is acceptable. After all, if there was a
production unit we would go and buy that instead! Needs must and all that.
Opinions welcome from those with this IRDA problem.
Ian - getting ready to visit the in-laws - depressing. And no play time -
suicidal ;-)
-----Original Message-----
From: Keith Doxey [mailto:ukha@xxxxxxx]
Sent: 12 January 2002 10:05
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] IRDA repeater
Hi Dave,
I have seen similar adapters before. They are OK for prototyping but not
really any good for production work as they are way too expensive.
>£5-00 to
hold a chip that costs about 3 or 4 quid just isnt viable. It also still
leaves you with the problem of actually having to solder something that
you
(well "I" at least) cant see !
My eyes have deteriorated seriously over the last 3 or 4 years and I think
it is partially down to the fat that I spend far too much time at a
PC......
and the onset of age (42 in 3 months).
Keith
-----Original Message-----
From: Dave McLaughlin [mailto:dave@xxxxxxx]
Sent: 11 January 2002 23:43
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] IRDA repeater
Check out www.winslow.co.uk as they do SMT to DIP adaptors and you can
order
via the website. Min quantity though but they are good and you can get the
exact device type from the maxim datasheet.
Dave...
-----Original Message-----
From: Keith Doxey [mailto:ukha@xxxxxxx]
Sent: 11 January 2002 23:32
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] IRDA repeater
AAAAARRRGGGGHHHH !!!!!
They are the really small ones.
I have some Maxim samples like that as well (different chips but just as
unuseable).
Keith
-----Original Message-----
From: Ian B [mailto:Ian@xxxxxxx]
Sent: 11 January 2002 22:45
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] IRDA repeater
Here is a picture of the offending chips. One of each is required at each
end of the repeater. Not simple as you can see.
http://www.mollyology.com/WebPages/Home/Index.htm
under projects, IR repeater, third line from the bottom is a link
Ian
-----Original Message-----
From: Keith Doxey [mailto:ukha@xxxxxxx]
Sent: 11 January 2002 22:04
To: ukha_d@xxxxxxx
Subject: RE: [ukha_d] IRDA repeater
I soldered wire to the chips and then mounted them in an IC socket so that
I
could plug it into a breadboard.
You have to be REALLY quick at soldering the other end of the wire to the
IC
socket otherwise the heat travels to the chip, melts the solder and that
end
of the wire falls off.
How do I know this.....coz it happened to me :-(
Watch out for shorts and burnt fingers as well. Bloody surface mount. ring
back tagstrips on 0.25 inch centres!!!
As for small, normal surface mount is useable compared to the ultrasmall
stuff they are doing now.
Keith
-----Original Message-----
From: Ian B [mailto:Ian@xxxxxxx]
Sent: 11 January 2002 19:40
To: Ukha_d
Subject: [ukha_d] IRDA repeater
Well guys and gals
The chips I ordered to try playing with turned up today and guess what, two
of the three are surface mount. Apart from soldering wires to the pins does
anyone have any idea how to attach these things. To say they are tiny is an
understatement. I am not sure my soldering skills are up to it.
Ideas please
Ian
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