User Manual

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Mica Thermofoil Heaters
Technical specifications
Specifications
Temperature range: -150 to 600°C (-238 to 1112°F).
Lead tab area: 538°C (1000°F) max.
Resistance tolerance: ±10% or ±0.5 W, whichever is greater.
Dielectric strength:
0.010” (0.3mm) insulation: 1000 VRMS.
0.020” (0.5mm) insulation: 2000 VRMS (recommended for
over 250 V).
Mounting: Must be clamped to heat sink using bolt holes
provided in heater and backing plate. See the mounting
diagram below. Please refer to Minco Engineering
Instruction #347 for detailed installation information.
Burn-in: Organic binders will burn off, producing small
amounts of smoke, when heaters are first powered. After this,
layers can separate so heaters should not be reinstalled.
Leadwire: Mica/glass insulated, stranded nickel-clad copper,
potted over termination with high temperature cement.
Maximum heater thickness:
Mica insulation Over heater element Over lead termination
0.010” (0.3 mm) 0.030” (0.8 mm) 0.200” (5.1 mm)
0.020” (0.5 mm) 0.050” (1.3 mm) 0.220” (5.6 mm)
Current capacity (based on 100°C max. ambient temp.):
AWG 22 - 8.0 A
AWG 20 - 9.0 A
AWG 18 - 11.0 A
Installation
instructions
Minco Engineering
Instruction #347
describes mica
heater
installation in
detail. Contact
Minco for a copy
or download the
document at www.
minco.com/
Backing plates
Backing plates
are 0.0625” (1.6
mm) thick stainless steel with pre-drilled holes matching the
bolt pattern of the specified model. These backing plates do
not have cut out areas for the lead bulge and may require
modification. Backing plates are available on www.minco.com/
Ceramic paper
Each mica heater is supplied with two pre-trimmed sheets of
0.125” (3.2 mm) thick ceramic fabric paper for use as a resilient
pad between the heater and backing plate. This paper does
not have a cut out area for the lead bulge. If the backing
plate being used does not have a cut out area for the leads
attachment you must use two pieces of this paper and make
this cut out in each. Contact Minco to order additional ceramic
paper.
Mica sheets
Additional layers of 0.010” (0.3 mm) mica trimmed to the
heater size are also available. Using an additional layer of mica
will increase the dielectric strength, but it will also reduce the
watt density limit by up to 50% across the temperature range.
If used on the lead bulge side of the heater then the mica must
be cut to allow for the ceramic and wires bulge on that side.
110
100
90
80
70
60
50
40
30
20
10
-200 -100 0 100 200 300 400 500 600
Watts / in²
Operating Temperature (°C)
17.1
15.5
14.0
12.4
10.9
9.3
7.8
6.2
4.7
3.1
1.6
Watts / cm²
0.020” (0.5mm) MICA
0.010” (0.3mm) MICA
Mica Heaters
Maximum Watt Density with Clamping
Rigid metal
backing plate
Ceramic paper
Mica
heater
Heated
piece
Mounting Diagram