SMT and the K3 - Nerves

[Bill W4ZV]

Don Wilhelm-4 wrote

So, there are OK alternate techniques, such as heating both ends of the
component at the same time as Alan Bloom pointed out, or my usual
solution of heating both ends alternately in rapid succession until the
component moves, or the two soldering iron solution.  These all work,
and IMHO have less probability for damage to the PC board than
physically breaking the component in two.

I agree with Don.  I've used one iron many times and 2-legged components usually slide off to the side.  Practice makes perfect.  Before attempting this on a good board, practice removing a few components on a scrap SMD board to perfect your technique.  

Components with more than 2 legs are more of a challenge, but I've used the cutting technique to remove 3 legged transistors without damage (so far anyway).

73,  Bill

[Tony Estep]

On Thu, Apr 19, 2012 at 10:56 PM, Ron D'Eau Claire <[hidden email]> wrote:

> ..."An engineer is a man who can do for five bob (25 cents) what anyone
> can do
> for a quid ($1)"...

============
and a government contractor is an outfit that can do for a guinea what
anyone else can do for half a crown.

Tony KT0NY



--
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[Terry Schieler]

I install a good number of SMDs.  I use much the same process as Ron D'Eau Claire mentions in his post and have never damaged a board.  The dental instruments have been a part of my three tool boxes for two dozen years and are very handy.  I've never had a problem removing an SMD by cutting it in half with very small, sharp flush cutters.

One thing that I experimented with for SMD mounting in tight situations is the use of a small model airplane fuel pump.  Available at most hobby shops, the fuel pump is a small, inexpensive electric motor with neoprene fuel lines attached to the input and output. They are used to pump model airplane engine fuel from the storage tank into the model's fuel tank at the flying field.  For SMD installation I only use the "inlet" line and free air, not fuel ;o)  

I cut the end of a 36" long neoprene fuel inlet line as square as I can.  I power the fuel pump with a small 12V power supply I have on my bench.  Once the pump is on, I use the vacuum of the inlet tube to suck onto the top of the SMD component (different size tubes can be adapted to accommodate larger or smaller SMD devices.)  The suction holds the SMD device quite firmly while I work the end of the tube to maneuver the SMD into place.  And, it continues to hold while I solder one end to the board.  After that, my fuel pump "third hand" is set aside until the next time its needed.

While this may sound a bit extreme, the idea came to me one day after "launching" half a dozen SMD devices across the room with tweezers.  I had "launched" a few distinct "expletives" as well.

You know what they say:  "Frustration is the mother of invention"..... Or, something like that.  ;o)

Terry, W0FM



-----Original Message-----
From: Ron D'Eau Claire [mailto:[hidden email]]
Sent: Thursday, April 19, 2012 4:23 PM
To: 'Elecraft Discussion List'
Subject: Re: [Elecraft] SMT and the K3 - Nerves

Keep in mind that all of the step-by-step procedures in the Elecraft documents were actually done by the writer, tested by others, and then refined and improved by customer feedback. That's in accordance with Wayne's basic requirements for Elecraft manuals. So if you take the time to follow them closely, you are getting the benefit of the experience of a great many others who have been there before you.

I have removed hundreds of two-terminal SMDs both by cutting them in half or by unsoldering one end at a time and lifting the part with never any damage to the pcb.


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