User Manual

49
Thermal Solutions Design Guide | Specifications subject to change
SmartHeat utilizes a resistive foil bus-pattern to deliver a voltage
potential to the underlying heating foil. This bus-pattern
may act as an inductor in certain configurations, but this is a
byproduct of the design and not the intended function.
How does SmartHeat respond to drastic changes
in environmental conditions?
SmartHeat strives to maintain a constant temperature. It will
produce high power when attached to a cold object, and will
rapidly warm the object to its set point while never exceeding a
prescribed safety temperature. As the heatsink and environment
change, the heater will increase or decrease its power output to
compensate.
I understand that SmartHeat is inherently self-
controlling, but is there any advantage to using a
secondary, external controller with SmartHeat?
It may seem counterintuitive to add a feedback loop to a
“controller-free” system, however there are situations where this
is a very reasonable approach. For instance, critical applications
may require two independent thermal shutoffs. While
SmartHeat can suffice for the first level of safety, an additional
thermal fuse or thermostat may be required as a secondary
level.
Other applications may require a combination of precise set
point control and built-in safety. The addition of an external
sensor allows the system to be tuned to a more precise set point
(especially in highly dynamic environments), while the core
SmartHeat layer gives the system a built-in safety mechanism.
Is it possible for SmartHeat to act as an On/Off
controller that is only active below a specified
temperature?
SmartHeat will gradually reduce its power output above
the designed set point for the system. It does not have the
same complete cut-off characteristic as an On/Off controller.
Instead, SmartHeat should be thought of as a no-overshoot PID
controlled system. SmartHeat will only draw as much power as
is needed to maintain its equilibrium set point. In a warm, low-
load environment, the heater will draw significantly less power
than in a cold, high-load environment. It will react to changes in
load by increasing or decreasing its power output to maintain
equilibrium.
Is the SmartHeat construction UL rated?
Minco’s SmartHeat construction is not yet UL rated. The
outer encapsulant (polyimide) is UL recognized, however the
core heating layer has not been tested. This testing is on the
roadmap for the product line and the results will be made
available as soon as they are ready.
What are the storage requirements for
SmartHeat technology? If heaters are stored for
years, will they be operational when they are put
into service?
SmartHeat should be stored in a clean, dry environment with
temperatures between -40°C to 100°C and humidity up to 95%,
non-condensing. In these conditions a SmartHeat device can be
expected to remain indefinitely prior to placement into service.
What is the durability of SmartHeat? How long of
a lifecycle can be expected?
Minco is currently collecting lifecycle data for SmartHeat. As of
the writing of this FAQ, various SmartHeat constructions have
been under power in a test environment for nearly 2 years with
no measurable degradation to heater performance. Minco does
not anticipate any issues using SmartHeat for critical, long-term
applications in excess of 10+ years and will continue collecting
data to confirm. It is however at the discretion of the customer
to validate SmartHeat for their end use application and required
longevity.
Is the SmartHeat construction durable enough to
withstand repeated bending?
Yes, SmartHeat is constructed from durable, flexible materials
that can withstand static or dynamic bending. It is important
that areas with dynamic bending be discussed early on, as this
can affect the positioning and layout of the termination area.
Can SmartHeat withstand pressure application
from lamination, clamping, or natural weight of
the heatsink?
SmartHeat is capable of withstanding high, uniform pressure.
It is important that the pressure be well distributed across
the heater’s surface to prevent puncture or physical damage.
Pressure lamination, mechanical clamping, and the weight of
common heatsinks are readily managed by SmartHeat.
What is the typical thickness of a SmartHeat
device?
Minco’s standard SmartHeat construction measures 0.013 inches
nominal. The minimum available thickness on a custom basis
is 0.011 inches nominal. Heaters that require pressure-sensitive
adhesive backing, a metallic heat spreader, insulating foam, or
high dielectric strength will have increased thickness and should
be quoted by Minco engineering.