[Elecraft] SMT and the K3 - Nerves

[Mel Farrer]

Well, you are both right and wrong.  Sorry,  The correct way to remove an SMT component is with the right tools.  Most of the accepted makers of SMT soldering and unsoldering equipment have gone to great lengths in minimalizing the undesirable effects of over heating by having available tips that match the size of the component like a saddle. The tip touches both the ends of the component and the solder bridge to loosen the part and with a vacuum pick either in the wand or standing by to suck the part of the PCB.  Honestly it is the most desirable way for minimum impact to the PCB trace.  In a off site situation I have done the leap frog on both ends and with a dental pick lifted one side then with tweezers hold the part and unsolder the offending side. The absolute worst why is to try and pry the part up while overheating one end.  Ugly.  Sorry, guys the had to give my two bits worth.  Buy the way the right tips are far less expensive than a
 damaged PCB.

Mel, K6KBE

Mel

--- On Thu, 4/19/12, Alan Bloom <n1al at sonic.net> wrote:

From: Alan Bloom <n1al at sonic.net>
Subject: Re: [Elecraft] SMT and the K3 - Nerves
To: "Ron D'Eau Claire" <ron at cobi.biz>
Cc: "'Elecraft Discussion List'" <elecraft at mailman.qth.net>
Date: Thursday, April 19, 2012, 2:58 PM

On Thu, 2012-04-19 at 14:23 -0700, Ron D'Eau Claire wrote:

> 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. 

On most two-terminal SMD parts (resistors, capacitors, etc.), the solder
terminal on each end extends on both sides (top and bottom).  So the way
I generally remove them is to tin the top of each contact with a little
solder and then lay the soldering iron tip across the top of the entire
part so that it heats both ends at the same time.  Once the solder
melts, you can push the part off the pads with a toothpick, Exacto
knife, whatever.

> Good light and your favorite magnifiers (if needed) to see clearly are
> essential. 

In my experience, being able to see the darn thing clearly is really the
key to successful SMT work.  I have a binocular microscope with built in
light that I bought brand new for about $300.  Whatever you use, make
sure to have a bright light, and some form of magnification is very
useful for those of us with middle-aged (or greater) eyes.

Alan N1AL


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