Removing surface mount diode

[Hamad bin Turki Salami]

I have a board that I need to add a diode to. The problem is that
the diode is coming off another board that I've cannibalized for
parts, and I don't know how to get the diode off that board. I
know very little about this stuff. I've removed components before
using an ordinary soldering iron and a solder pump. However,
this diode is tiny and surface mounted, which seems to make things
a bit harder. I tried applying a soldering iron to the leads while poking
at the diode with a metal probe. Eventually, I cracked the diode
this way. Fortunately, the board has a few more identical diodes, so I
have another few shots at this.

Is there a trick to it?

 

[repair]

Hamad bin Turki Salami <[email protected]>
wrote in

I have a board that I need to add a diode to. The problem is
that the diode is coming off another board that I've
cannibalized for parts, and I don't know how to get the diode
off that board. I know very little about this stuff. I've
removed components before using an ordinary soldering iron and a
solder pump. However, this diode is tiny and surface mounted,
which seems to make things a bit harder. I tried applying a
soldering iron to the leads while poking at the diode with a
metal probe. Eventually, I cracked the diode this way.
Fortunately, the board has a few more identical diodes, so I
have another few shots at this.

Is there a trick to it?

Have to use rosin flux. Get rid of the soldering pencil and get a
temp controlled weller like soldering station, $40.00. Set at 725F.
Get the right size solder wick that is 1/8" wide. Don't use wick
that is 1/4" wide, that's too big. The solder hand pump should work
but most of the time the solder pump tip is too big ans sometimes
you suck up the SMD part into the handheld solder pump, nozzle hole
is too big. The main key is you have to use rosin flux. Clean off
flux with denatured alcohol. The standard tool to use is a hot air
desoldering station.

 

[Ken]

I have a board that I need to add a diode to. The problem is that
the diode is coming off another board that I've cannibalized for
parts, and I don't know how to get the diode off that board. I
know very little about this stuff. I've removed components before
using an ordinary soldering iron and a solder pump. However,
this diode is tiny and surface mounted, which seems to make things
a bit harder. I tried applying a soldering iron to the leads while poking
at the diode with a metal probe. Eventually, I cracked the diode
this way. Fortunately, the board has a few more identical diodes, so I
have another few shots at this.

Is there a trick to it?

I find using an Exacto knife and a low wattage soldering iron works to
lift each end of the device. Regardless of the technique, you must be
very careful.

 

[[email protected]]

Mr. Salami asked:

Is there a trick to it?

TWO soldering irons, heat up each end of the component at the same time
and lift off.

Seems like a lot of effort to get at a part that probably would cost a
penny or two if you bought it.

Tim.

 

[kip]

I use tweezers and a fine tip Iron...Always works here.

 

[3T39]

Hello, Hamad!
You wrote on Thu, 12 Jan 2006 02:04:47 -0700:

HbT> I have a board that I need to add a diode to. The problem is that
HbT> the diode is coming off another board that I've cannibalized for
HbT> parts, and I don't know how to get the diode off that board. I
HbT> know very little about this stuff. I've removed components before
HbT> using an ordinary soldering iron and a solder pump. However,
HbT> this diode is tiny and surface mounted, which seems to make things
HbT> a bit harder. I tried applying a soldering iron to the leads while
HbT> poking at the diode with a metal probe. Eventually, I cracked the
HbT> diode this way. Fortunately, the board has a few more identical
HbT> diodes, so I have another few shots at this.

HbT> Is there a trick to it?

With best regards, 3T39. E-mail: [email protected]

 

[3T39]

Hello, Hamad!
You wrote on Thu, 12 Jan 2006 02:04:47 -0700:

HbT> Is there a trick to it?

For some reason the text I wrote wasn't visibleon my last post, Very strange
OE behaviour, anyway I'll try again here

If your taking the parts from a scrap board, you might like to try using a
blowlamp applied to the back for a few seconds and then quickly hit the edge
of the board against the side of a container like a buiscuit tin or
something (held firmly so it doesn't fly up). you will soon get the hang of
it, and a lot of components can be recovered at once this way, even the
multi pinned monsters that you will never probably use. The only trouble I
find, is you get solder on the recovered devices which you then have to
clean off. empty the tin every time so you don't build up a lot of solder on
the items. of course you should invest in the right equipment if you want to
do it properly, but if like me it's just to experiment and learn, then this
brute force method works OK. I use a hot air gun when I do this, but a
blowlamp works just fine. A few words of caution, 1/ don't get the board too
hot, the fumes stink and may even be dangerous. 2/ do it outside, because
the fumes stink and might even be dangerous, 3/ wear gloves and be carful,
because the fumes stink and might even be dangerous.

With best regards, 3T39. E-mail: [email protected]

 

[Smitty Two]

I have a board that I need to add a diode to. The problem is that
the diode is coming off another board that I've cannibalized for
parts, and I don't know how to get the diode off that board. I
know very little about this stuff. I've removed components before
using an ordinary soldering iron and a solder pump. However,
this diode is tiny and surface mounted, which seems to make things
a bit harder. I tried applying a soldering iron to the leads while poking
at the diode with a metal probe. Eventually, I cracked the diode
this way. Fortunately, the board has a few more identical diodes, so I
have another few shots at this.

Is there a trick to it?

I don't know what the quality of your equipment is, or your skill level
with a soldering iron. But, the *best* way to do this is to use an SMD
removal tweezer, which heats both ends simultaneously. Failing that:

1) An appropriately sized soldering tip, properly tinned. If it isn't
shiny, throw it away and get a new tip.

2) Rosin flux, as another respondent said.

3) Solder wick, as was suggested. "soder wick" (sic) is the best brand
name.

4) Put a generous drop of flux on the thing, and wick up as much solder
as possible. If your technique is correct, this will take no longer than
one or two seconds per end.

5) With fine tipped needle nose pliers, rotate the component to snap the
part loose from the tiny amount of solder still holding it to the board.
Lifting one end sometimes works, and sometimes breaks the end cap.
That's why I like the twist. If you need more than an inch pound or two
(wild ass guess) of torque, you didn't wick up enough solder.

If the diode is very small, you can skip the solder wick, use the flux,
heat both ends simultaneously by laying the tip parallel to the
component, and flick it off the board.

Note that low powered or low temp soldering irons are useless. Get a
decent iron and crank it up to 800. You can solder or desolder with
*much* shorter dwell times, exposing the component to far less heat than
using an underpowered iron and holding it on there for five or ten
seconds. Soldering small components shouldn't take any longer than
blowing out a candle.

 

[Dr. Anton T. Squeegee]

I have a board that I need to add a diode to. The problem is that
the diode is coming off another board that I've cannibalized for
parts, and I don't know how to get the diode off that board. I

Is there a trick to it?

Yes. You should consider investing in the correct tools for the
job. Specifically, a desoldering tool known as 'Hot Tweezers.'

Pace makes such, as does Weller and other companies. You can often
find such at relatively low prices on Greed-bay, or at ham radio swap
meets.

Happy hunting.


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"

 

[Leonard Caillouet]

A K tip on a Haako or similar wide wedge or knife tip is wide enough to
reach both ends of the device. Just a dab of fresh solder on either end and
touch both ends at the same time and they come right off.

Leonard