[hpsdr] Atlas, How do I hand solder this thing?

[Leon Heller]

----- Original Message ----- 
From: "Philip Covington" <p.covington at gmail.com>
To: "Robert McGwier" <rwmcgwier at comcast.net>
Cc: <hpsdr at hpsdr.org>
Sent: Monday, June 19, 2006 12:44 PM
Subject: Re: [hpsdr] Atlas, How do I hand solder this thing?


> ***** High Performance Software Defined Radio Discussion List *****
> 
> On 6/19/06, Robert McGwier <rwmcgwier at comcast.net> wrote:
>> ***** High Performance Software Defined Radio Discussion List *****
>>
>> For quite some time I have taken the bull in the china shop approach
>> with 100% success (and it has the benefit of appealing to my nature ;-)
>> ).  Tack the corner and then get solder everywhere on the remaining pins
>> for the IC (either DIP and quad leaded).  The detailing is then done
>> with solder wick to remove the excess and shorts.  Inspect with
>> magnification.  This beats the heck out of attempting to solder single
>> leads at a time.
>>
>> Bob
> 
> This method works with pre-tinned boards - not sure about the gold
> boards like the Janus and non-alpha Atlas:
> 
> The approach I take with the 0.5mm stuff is to tack down two corners,
> then flood with flux.  There is usually enough solder on a tinned tip
> and the pre-tinned board to be able to slowly drag the tip of the iron
> at an angle across the pins.  The surface tension of the solder in
> addition to the copious flux keeps solder bridges from happening.  I
> think I dwell about 2-4 seconds per pin with the tip at an angle so it
> is in contact with more than one pin at a time.  I then grab my
> Pakistan-made dental pick type instrument (purchased from Newark) and
> drag it lightly over each pin while looking through the microscope or
> magnifier.  The tip of this pick is small enough that it can fit
> between each 0.5mm pin. You can immediately see and hear if any of the
> pins have not soldered.  Using this method I have not had to remove
> bridges with solder wick.   Like I said, not sure how this is going to
> work with the gold plate boards...
> 
> De-soldering QFPs works similarly.  I flood with flux then use the
> dental pick to "lift up" the pin while applying heat from the
> soldering tip.  This only takes about 1 second per pin.  I was able to
> unsolder a 100 pin 0.5mm QFP in less than 2 minutes using this method.
> If you are not too wild about pulling up on the pin, the deflection
> is so small that the part can be easily reused by setting it on a flat
> surface and using the pick to straighten/lower any of the pins that
> need it.
> 
> Of course, using SMT soldering equipment like a hot air system you
> solder/unsolder these type of components too.  The reason I mention
> the above methods is that they work with a minimal investment in
> tools.

I use ChipQuik for desoldering fine-pitch devices:

http://www.chipquik.com/

73, Leon

 1150721340.0