[TriEmbed] APA102 unsoldering

[Pete Soper]

I was going to suggest this too. Simply removing the part with cutters, 
Dremel, etc can save a ton of stress on nearby components and just leave 
a simple solder-sucking job to prep the area.

Reminds me of four and a half eons ago when a minicomputer at my school 
died and the service tech used (by today's standards omniscient)  
diagnostics and his equipment to identify the specific MSI logic 
component, snipped the tops of the DIP's leads, slurped the ends and 
solder out, and soldered a new chip in. The computer was running again 
about a half hour after he walked in the door.
-Pete


On 06/22/2016 11:35 AM, Robert Gasiorowski via TriEmbed wrote:
> Hot air is the best, but it's not always possible to use it.
> When I need to remove SMD part and cannot use hot air, I crush/cut it 
> with pliers and unsolder each lead separately. This assures least heat 
> stress on pads.
>
> On Wed, Jun 22, 2016 at 11:13 AM, Brian via TriEmbed 
> <triembed at triembed.org <mailto:triembed at triembed.org>> wrote:
>
>     Seconded. Temperature and time is everything.  Not too hot and not
>     too fast.  The best way to desolder SMT devices is to heat
>     everything, and do it gradually.  If you have it available, use
>     hot air and don't go above 280 C.  It will take a fairly long time
>     for the solder to melt, but the solder also has the highest
>     thermal mass; that is, the plastic will heat up a lot faster than
>     the metal.  If you're dumping heat in at 350 C, your plastic bits
>     will hit 350 (and be a molten mess) way before the metal even gets
>     near 280 (average reflow temp).
>
>     Patience.
>
>     -B
>
>     On 06/22/2016 08:59 AM, Adam Haile via TriEmbed wrote:
>
>         Also, what temp is your iron set to? Realizing that the
>         ChipQuik only
>         helps in removal, but since those LEDs are designed to be
>         reflowed, they
>         should certainly survive solder melting temp. One thing that
>         might cause
>         an issue is using lead-free solder, especially of a cheaper
>         alloy which
>         has a much higher temp. If you are using lead-free, try leaded
>         and keep
>         the iron <= 600.
>
>         On Wed, Jun 22, 2016 at 8:43 AM, Alex Davis via TriEmbed
>         <triembed at triembed.org <mailto:triembed at triembed.org>
>         <mailto:triembed at triembed.org <mailto:triembed at triembed.org>>>
>         wrote:
>
>             Anyone have any success with unsoldering APA102 LEDs
>         without ruining
>             them? It seems they are made of really shitty
>         thermoplastic which melts
>             at about the melting point of the solder. I had one go bad
>         in my 44x8
>             matrix, and I got it off by using a broad tip to reflow
>         one side at a
>             time while lifting with tweezers. I'd say the package has
>         the thermal
>             resistance of the sort of plastic cheap header strips are
>         made of. It
>             was a ruined plastic blob by time I got it off.
>
>             As to the repair, I am thinking I will just cut an LED off
>         a spare strip
>             and solder it down on top of the blank spot. It won't look
>         as nice but
>             it seems like it will have the highest change of success
>         and of not
>             ruining the mounting strip.
>
>             BTW these APA102 have in and out for both data and clock,
>         and in my case
>             an LED stopped outputting anything on data out, causing
>         the whole rest
>             of the strip to die. Thankfully it was just one unit, but
>         it gives me
>             pause to consider building anything large and expensive
>         out of these
>             things. My setup was working fine before I peeled off the
>         backing tape
>             and glued it on to the enclosure.
>
>             Alex
>
>             --
>             "The theater of noise is proof of our potential."
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