Depending on the environment where the electronic PCB are integrated (humidity, vibrations, salt spray, high temperature, etc.), several solutions are possible:
- RTV silicone
- 2 components epoxy resin
- 2 components polyurethane resin
- UV curing glue
RTV silicones cure with the moisture of the air and provide excellent mechanical protection due to
their flexibility. Often used to maintain electronic capacitors, RTV silicone adhesives absorb potential shocks and vibrations.
When no movement of the components is tolerated, two-component epoxy or polyurethane
solutions are often used. These glues are generally more rigid and prevent any movement of the
components. A glob top can even sometimes be used to completely protect some sensitive
components or even the entire electronic system against all external aggressions (chemical
aggression, water penetration, abrasions, hacking, etc.). These solutions can be applied manually
using two-component cartridges and a static mixer to mix the resin with its hardener, or more
industrially using a in line machines.
Nevertheless, more and more gluing applications are made with UV curable glues. These solutions allow
bonding up to 5mm thick with a drying time of a few seconds under UV lamps. These UV glues have
the advantage of being available in different ways: fluid to very viscous, flexible to very rigid, with or
without tracer… ABchimie has real expertise and can modify formulations of the glues in order to
perfectly meet their customer specifications.
The main advantage of UV glues is that they reduce the size of production lines and reduce
production time due to their very quick drying time. The application of the glue can be done at the
same time as the deposit of the conformal coating, and this with a single passage in the UV oven.
Concrete case: ABchimie has developed the ABchimie 6025 UV glue which is a very high viscosity and
flexible mercury or LED curing glue (similar to a standard RTV silicone). This product allows handling of
the PCB directly after curing and has real advantages for customers with a high production volume. It
is even possible to:
– Glue components in one side of the PCB
– Cure it with a UV lamp
– Flip the PCB
– Put the PCB on the other side
– Put the PCB in a reflow oven to solder the top & bottom side at the same time.
More information: www.abchimie.com
