In message  <[log in to unmask]> [log in to unmask] writes:
> Anyone have any experience with a SMD removal kit called Chip Quik?  I used
> it on a few of my test cards and was impressed.  Are there any restrictions
> on the use of this type of material?  Any good or bad experiences with it?
> Any info would be appreciated.  Email [log in to unmask] if you'd prefer.

Chip Quik is a low melting temperature solder alloy, containing bismuth, IIRC.
It works by being melted into the existing solder joint, mixing with it and
thereby lowering the liquidus temperature. It is then easy to keep all the
solder joints of, say, a QFP molten at the same time with a simple hot air tool
or iron, and lift off the device.

The concern is that you will leave behind a thin intermetallic layer of bismuth
containing alloy on the pcb pads. Bismuth is not very mobile, so when you make
the new joint, the bismuth probably stays where it is i.e. in a thin layer next
to the pad. Bismuth is also very brittle (take a piece of Chip Quik alloy, and
bend it - it breaks easily, unlike 63/37). I wonder how reliable this joint
will be in future, and whether is it more likely to crack at this interface? I
dunno, no data, just a query.

I would guess that it would be fine to use or your TV remote control repair,
and a bit reckless on your jet fighter engine control system. I would be very
interested to see any test data to prove or disprove these thoughts.

Peter
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Peter Swanson                                              Oxfordshire, England
INTERTRONICS
[log in to unmask]                      http://www.cygnetuk.demon.co.uk

Suppliers of materials and consumables to the electronics & related industries
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