Conformal coating improves the reliability and life of solar inverters
the process where fluid is rapidly ejected
through a nozzle and uses the fluid mo-
mentum to break free from the nozzle. A
discrete volume of material is ejected with
each jetting cycle. Jetting is fast because
when moving from one dispense location
to the next there is no Z-axis that has to
move up and down. High flow rates can
be achieved, fluid can be deposited in
tight places with much smaller keep-out
areas, and the ability to use a wide range of
fluids that are deposited in a vast number
of configurations allows for flexibility. In
inverters, where there are components of
different heights and irregular component
placement, using a jetting system makes it
possible to easily accommodate the coating
requirements while working with the selec-
tivity requirements of closer component
placement.
Several different types of applicators
are available for high volume coating
platforms, so the correct applicator can be
matched to the material being dispensed.
For additional precision without com-
promising throughput, applicators with
Figure 1. Conformal coating jet for applying coating materials to highly selective areas.
multiple modes of operation or multiple
applicators on the same system can be
used.
and the coating hits the correct target. While the solar and photovoltaic
They make programming easier and dis- industries have a long history, the industry
advancements in conformal
pensing more accurate. Process control and size is rapidly expanding. Looking at exist-
coating systems
feedback systems result in better quality, ing technologies used in other electronics
Today’s conformal coating systems provide
higher reliability, and reduced variation industry applications can offer solutions
up to 30 percent faster throughput than
in the coating process. Today’s conformal to some of the manufacturing needs the
just a couple of years ago, and options
coating systems enable better process solar and photovoltaics industries now
include vision systems, closed-loop pro-
control as systems include technologies to face. Decreasing cost doesn’t have to mean
cess controls, traceability and advanced
control and maintain the viscosity of the decreasing reliability. Conformal coating
integrated software for high quality and in-
fluid and monitor its flow. Having closed- is an easy and effective way to get that reli-
creased productivity. Advanced monitoring
loop process control and traceability dur- ability in photovoltaic inverters.
enables the manufacturer to keep the coat-
ing the coating process provides a record
ing process in control and allows for statis-
of the conditions and settings used in the
tical process control (SPC). Fluid and air
conformal coating process. System control
pressures are set and monitored through
reduces wasted time and fluid, increases
software-controlled electronic regulators,
yield, and results in a lower total cost of
allowing traceability and flexibility for
ownership.
these critical parameters. Data logging and
automatic adjustments of other parameters
additional dispensing and coating
such as fan widths, fluid temperatures,
applications in the pV industry
and flow rates, further ensure the quality
Jet dispensing and conformal coating have
of the coating process. Regulator knobs
found a place in several other solar and
and controls are being removed from the
PV applications. Coating has been used to
equipment so critical parameters can’t be
coat thin-film PV materials on substrates,
changed without engineering approval.
as protection materials for the solar cell
Having the controls programmed through
edges and concentrating optics, and for
the software maintains a consistent process
the electronics around the solar cell. This
and eliminates constant tweaking of the
has been accomplished with a dual valve
parameters. The process and material pa-
system, which can be used to apply two
rameters that are specified are stored with
separate fluids during the manufacturing
each program for each product to maintain
operation. Glue can be dispensed to attach
engineering level control of optimized
the concentrating optics onto PV chips.
parameters.
Solar etch materials can be applied as can
Vision systems help to ensure that the
silver contacts and electrolytes which can
work-piece is properly placed and aligned
be used to dye the solar cell.
www.globalsolartechnology.com Global Solar Technology – March/April 2009 – 17
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