SEPTEMBER 2021 I DESIGN007 MAGAZINE 23
By placing connectors and components
that must not be coated along one edge of the
assembly, the conformal coating application
process will be simplified. It is also advisable
to avoid large arrays of discrete components,
which can pose a huge coating challenge due
to the high levels of capillary forces present.
Tall components can also present challenges of
their own by the creation of shadowed or hard
to reach areas. Splashing is another associated
problem. e trick is to avoid placing tall com-
ponents next to "must-coat" components to
avoid this eventuality.
Know Your Component Zones
Lastly, it's worth noting that being aware of
what kinds of components should be coated
or should not be coated will provide more
flexibility to the coater in assembly opera-
tions. When a component will not be coated,
it becomes a "keep out" zone. e engineer-
ing drawing should not only identify compo-
nents but identify the tolerance on that keep
out zone. It is important to be very specific
on the tolerance. e manufacturer needs to
know exactly where you do and don't want
coatings. It is best practice to specify the areas
that need to be coated and the areas that don't,
as well as the "don't care" areas, to help the
coating process run as smoothly as possible.
Avoid vague statements at all costs in an engi-
neering drawing. is is especially true when
specifying coating around connectors.
Over the following months I hope to pro-
vide more useful tips and design advice that
will help make life a bit easier for those who
are responsible for making the decisions on
protecting components and circuitry. I hope
the foregoing will help you with your coating
process. Look out for my next column where
I will be exploring more coating tips and tech-
niques.
DESIGN007
Phil Kinner is the global busi-
ness and technical director of
conformal coatings at Elec-
trolube. To read past col-
umns or contact Kinner, click
here. Download your free copy
of Electrolube's book, The
Printed Circuit Assembler's Guide to… Conformal
Coatings for Harsh Environments, and watch the
micro webinar series "Coatings Uncoated!"
