Heater resistors are used in a wide variety of applications from simple demisting elements in car windscreens to complex medical applications where demand is increasing for custom heater resistors to satisfy the requirements of demanding and diverse medical applications. In this post, we discuss the information required by a specialist resistor manufacturer to design and deliver an application specific heater resistor.
When specifying an application specific resistor the key tradeoff is often size versus power rating. This is particularly important in many medical heater applications where space may be limited. Often heat must be delivered to a specific point contact, in a controlled manner for a specific period of time.
The power rating of a resistor defines the maximum energy (heat) a resistor can safely dissipate without compromising its in service life. In general terms the greater a resistors surface area the more power it can dissipate. Resistor dimensions are also influenced by the choice of substrate material.
Information required by the manufacturer of custom heater resistors includes (as a minimum)
Termination type, position and material
Heat profile required
Ambient air temperature of environment
Expected in service life
Thick film is an excellent technology choice for custom heater resistor designs. The technology has excellent heat transfer properties, thermal efficiency and temperature uniformity across a surface. Substrates may be custom designed to fit in small, difficult to access, areas and apply heat exactly where it is required. The technology is also robust with excellent moisture and chemical resistance.
With the application parameters identified it is important to work with a specialist manufacturer who understands resistor technology, materials and design and manufacturing limitations to ensure custom heater resistors are delivered that perform reliably to specification over their full in service life.