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HEATFLEX SILICONE RUBBER HEATERS

ELEMENT SELECTION

HEATFLEX silicone rubber heaters may contain either an etched foil element or a wire wound element. In both cases the heater’s element pattern is laid out using CAD. Basic element selection criteria are as follows:


ETCHED FOIL ELEMENT

Silicone rubber heaters with etched foil circuit elements begin as sheets of a metallic foil and silicone rubber laminate. These sheets are then printed with a pattern of the designed circuit. Next, the sheets are chemically etched with the printed portion remaining. After cutting individual circuits apart, the top layer of silicone rubber is laminated over the top of the circuit. The foil thickness can range from .0005" to .004" depending on the required resistance of the designed HEATFLEX heater element. Several different material types can be utilized again depending on the heater resistance. Because the etched circuit element is flat foil, the element itself can cover up to 80% of the heater area.
*Selection Criteria*
Better choice for high watt density heaters (those over 6 watts per sq inch). Can also be used for watt densities less than 6. Excellent choice for heaters that require multi-zoned wattages or heaters that has many holes and/or cutouts. May provide an economic advantage for high volume applications. Offers excellent circuit repeatability. Relatively expensive for single short run orders due to initial one time artwork and steel rule cutting die charges. May not be suitable for some high resistance heaters.
*Specifications*
Size: up to 22" by 28" Standard Thickness: .030" Maximum Watt Density: 60 watts per sq. inch Standard Maximum Resistance Density: 115 ohms per sq. inch Maximum Operating Temp: 450° F	Minimum Operating Temp: -70° F Maximum Voltage: 600 volts Wattage Tolerance: +5% -10% for UL & CSA heaters Standard Dimensional Tolerances: + or - .062". Tolerances of + or - .015" can be held if specified.

WIRE WOUND ELEMENTS
Wire wound silicone heaters begin with one to five strands of resistance wire that are machine wound, in most cases, on a fiberglass core for strength. Combinations chosen are based on the desired resistance and flexibility requirements of the final heater. This element is then wound around dedicated tooling and transferred to a layer of silicone rubber. Another layer of silicone rubber is then placed over the element to complete this heater.
*Selection Criteria* Provides excellent repeatability for short run orders. Better choice for flexing application Adapts to contoured surfaces with relative ease. Advantageous in high resistance applications and heater sizes not lending themselves to etching process. Prototypes can be delivered quickly at minimal cost.
*Specifications*
Size: 36" by 70"(consult Kelvin for other sizes) Standard Thickness: .040" for permanently attached heaters; .055" for removable heaters Maximum Watt Density: 12 watts per sq. inch Standard Maximum Resistance Density: 1000 ohms per sq. inch Maximum Operating Temp: 450° F	Minimum Operating Temp: -70° F Maximum Voltage: 600 volts Wattage Tolerance: + or - 5% for UL & CSA heaters Standard Dimensional Tolerances: 0 to 12" + or - .0625";12 to 24" + or - .0125"; 24 to 36" + or - .1875"; over 36" + or - .75". Tighter tolerances can be held if requested.