App. Note 16 - Aids to IC insertion
General:
While Stabilant 22/22A/22E isknown primarily for its
property of providing the reliability of a soldered joint without forming
a physical bond, it is becoming increasingly used in a dual role: not
only for the reliability increase, but as an insertion aid for both machine
and hand-insertion of IC's!
How does it assist in the insertion of IC's?
Quite often, when an IC is inserted in a socket, one or more of the
pins will buckle and bend-under. Sometimes this is not detected until the
system is powered-up, and it shows a fault. In some cases, it might not
be detected until some program does not run properly! Because of the large
number of IC's used in many computers, the job of locating a single bent-under
pin is often very difficult. And when a number of boards are being hand-stuffed
with "socketed" IC's, there is an excellent chance that this problem will
occur.
When Stabilant 22 is used on the IC pins, its lubricating qualities
reduce the insertion forces on the individual pins, making it much less
likely that any pin will be bent-under.
How can Stabilant 22 be applied to IC pins?
An applicator can be made by using a rectangle of the conductive foam
used to transport static-sensitive IC's. Using five-minute epoxy, glue
this material on the bottom of a container,-such as a petri-dish or a shallow
tin. Stabilant 22 (as the concentrate) is then poured over the foam
pad.
To use, the IC is picked out of the dispenser with a standard tool,
and its pins thrust into the pad in order to wet them with the Stabilant.
(While
a small amount will b left on the bottom of the IC this will not affect
its performance.) The IC is then inserted into its socket in the usual
fashion. It will be noticed that there is less insertion resistance.
The use of Stabilant 22 is not a substitute for having the pins
of the IC properly lined up or aligned in properly spaced parallel rows.
While hand insertion of IC's without the use of a tool is made much
easier when Stabilant 22 is used as a lubricant, we suggest that
a tool be used wherever possible.
Can Stabilant 22 be diluted?
The lubricating quality will, of course, be reduced as the Stabilant
is
diluted. If it is necessary to dilute it, we would suggest that a small
amount of isopropyl alcohol be used - no more than 1 part of isopropyl
alcohol to 3 parts of Stabilant 22 by volume.
Can Stabilant 22A be used in this application?
Yes, but as Stabilant 22A is diluted 4:1 with isopropyl alcohol,
much more will have to be applied to the pins and its lubricating qualities
will be realized only after the alcohol evaporates. This could slow down
the process of IC insertion.
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