Re: [OT] surface mount components

Tony Fleming
 

Thank you for more information about the Crazy Glue, vapors.... My friend
did this when he replaced couple SM parts. I'm sure if you used this an all
SMD's it would cause problem if soldered in a oven.

I'll look for the glue - quick search on Google :
https://www.hisco.com/Catalog/Adhesives-Sealants-Tapes/Adhesives/Epoxy-Adhesives/114004-1998


On Thu, May 16, 2019 at 11:35 AM Glenn Little <glennmaillist@...>
wrote:

Crazy glue will not withstand soldering temperature.
When heated to soldering temperature, it gives off vapors that probably
are not good to breath.

IPC-SM-817A address adhesives for SM parts.
This document does not appear to be available unless bought from IPC.
One adhesive that claims that it is complaint is EPIBOND 7275-1 10CC EFD.
This is an epoxy and I suspect that all adhesives that should be used
will be epoxy based.

Glenn

On 5/16/2019 11:55 AM, Tony Fleming wrote:
Nice information for people who do not use SMD's very often.
Some people use Crazy Glue to hold the part down - just a small drop -
before soldering it.
Is there anyone who thinks that using glue is not a good idea?

On Thu, May 16, 2019 at 9:43 AM Chuck Harris <cfharris@...> wrote:

If you do the soldering right, heating all of the joints
at once, the surface tension of the solder will rotate the
part around into alignment.

One of the contracts we all have with Murphy relative to SMD
rework is that we must melt all of the solder joints at the
same time so that we can avoid introducing tensions in the
parts that can cause breakage. The issue is especially bad
with fragile leadless parts like SMD capacitors. If you see
a capacitor that is "tombstoned" (eg. one side higher than
the other) it is under stress.

-Chuck Harris

Bob Albert via Groups.Io wrote:
One method that works for me is a small C clamp. I put the part
about
where I want it and clamp it lightly. Then I nudge it into the exact
spot
and do the soldering. It worked great when I repaired the HP generator;
the job looks as good as the original.
Of course, in the middle of a large board you can't do this. What also
may work is a dab of plastic acrylic cement. While it's liquid you can
use
it to hold parts where you like. Then nudge a bit while it starts to
set.
If the clamp's jaws are too large you can put a bit of metal or plastic
between them and the part to improve access for soldering. Or just put
it
off center and solder one side of the part; once you do that it will
stay
in place while you do the other side.
For repairs it's usually enough to use residual solder. For fresh
installation you need to add some, of course. In the latter case,
solder
the board before you install the part and then you can clean up any
bridges. Once done, you can treat it as a repair.
These little ideas can be adapted to your own situation and dexterity
and tools.
Bob
On Wednesday, May 15, 2019, 8:10:15 AM PDT, John Griessen <
john@...> wrote:
On 5/15/19 6:26 AM, David Kuhn wrote:
Then
there is the sticky tweezers. They fustrate me too. Lately, I have
to
clean them with ISO to keep the parts from sticking from them.
I have these antimagnetic and anti static tweezers for sale that work
well
and can be hand formed to accept large objects:

https://www.ecosensory.com/tek/tweezers-1.jpg
https://www.ecosensory.com/tek/tweezers-2.jpg

Contact off list if interested.








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Glenn Little ARRL Technical Specialist QCWA LM 28417
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"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"




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