NTC THERMISTORS:
TYPE 1F, 2F
DESCRIPTION:
THERMOFLAKES consist of thick film thermistors
which have no substrate backings. Since their lead-
wires are fired directly into their electrodes, solder
leaching and diffusion are completely eliminated.
This results in excellent, low noise ohmic contacts.
DIMENSIONS:
APPLICATIONS:
The high surface-to-mass ratio associated with a
THERMOFLAKE results in low heat capacity and
fast response time. THERMOFLAKES are ideally
suited for infrared detection. Since the thermistor
materials used are good absorbers of IR energy,
satisfactory results may be obtained without the
use of special absorption coatings.
MOUNTINGS:
DATA:
STANDARD THICKNESSES AND
EFFECTIVE AREA
THERMOFLAKES are available in standard thick-
nesses of 25 microns (0.001") and 50 microns
(0.002"). Area ranges from .020" x .020" to .120"
x .120". See Table A.
THERMOFLAKES with larger and smaller cross sec-
tions are available on special request. When used
for detecting IR energy, the flake is mounted in an
inverted position so that its black side faces the
incident radiation and its electrodes face away from
the IR source. This results in greater efficiency since
the entire flake area becomes the effective area.
COATINGS AND FILTERS
Absorptive coatings, such as 3M Black Velvet, are
available on request. The absorptivity of the
uncoated THERMOFLAKE is reasonably flat at
approximately 40-45% in the range of 5-15
microns. Although an absorptive coating will result
in a somewhat flatter spectral response at almost
twice the absorptivity, it will not necessarily improve
the sensitivity. This is due to the fact that the
increased absorptivity is obtained at the expense of
increased thermal mass. Coated germanium filters
which exhibit a passband of 7.5-13 microns are
available from stock. Other windows are available
on request.
MAXIMUM AMBIENT TEMPERATURE
THERMOFLAKES may be operated at temperatures
as high as 300°C although maximum stability is
obtained at temperatures below 105°C.
BOWTHORPE THERMOMETRICS
Crown Industrial Estate, Priorswood Road
Taunton, Somerset TA2 8QY UK
Tel +44 (0) 1823 335200
Fax +44 (0) 1823 332637
THERMAL AND ELECTRICAL PROPERTIES*
•
Dissipation Constant: 0.2-0.4 Milliwatt/°C
•
Thermal Time Constant: 35-75 Milliseconds
*Values specified are for the THERMOFLAKE mount-
ed by its leads in still air at 25°C. The actual value,
within the range provided, depends upon the cross
section and thickness of the flake. Time constant
values represent cooling response to an electrical
pulse which does not heat the leads significantly.
RESISTANCE RANGE
50 K ohms to 2 Megohms, see Table B for standard
values. Values between 1K ohm and 100 Megohms
are available on special order.
TEMPERATURE COEFFICIENT
Varies between -3.9%/°C and -4.4%/°C depending
on size, thickness and the resistance of the
THERMOFLAKE.
KEYSTONE THERMOMETRICS CORPORATION
967 Windfall Road
St. Marys, Pennsylvania 15857-3397 USA
Tel +1 (814) 834 9140
Fax +1 (814) 781 7969
THERMOMETRICS, INC.
808 US Highway 1
Edison, New Jersey 08817-4695 USA
Tel +1 (732) 287 2870
Fax +1 (732) 287 8847
TABLE A: THERMOFLAKE SIZES
ORDERING CODE
Inches
L1
(mm)
Inches
L2
(mm)
F20
.020
(.5)
.020
(.5)
FB20
.020
(.5)
.040
(.5)
F40
.040
(1)
.040
(1)
FB40
.040
(1)
.080
(2)
F80
.080
(2)
.080
(2)
FA80
.080
(2)
.120
(3)
F120
.120
(3)
.120
(3)
TABLE B: STANDARD RESISTANCE VALUES
Resistance @ 25°C
(in ohms)
50k
100k
200k
500k
1 Meg
1.5 Meg
2 Meg
Ordering Code
503
104
204
504
105
155
205
TABLE C: STANDARD TOLERANCES:
Tolerance Code Letter
± % Tolerance at 25°C
J
5
K
10
L
15
M
20
N
25
P
30
Q
40
R
50
Non-standard (specify value)
CODING:
The ordering code should be specified as follows:
A500 - 2
F40
M
105
N - GF
Filter (when applicable). Specify GF for germanium filter.
Tolerance code letter per Table C.
Standard resistance values, @ 25°C, use code from Table B
THERMOFLAKES LEAD CONFIGURATION
“J” denotes adjacent leads, see Figure J.
“P” denotes opposite leads, see Figure P
.
“D” denotes double adjacent leads, Figure D.
“M” denotes mounted THERMOFLAKE. See Figures A500 thru A505.
THERMOFLAKE Sizes
F20 denotes .020" x .020"
FB20 denotes .020" x .040"
F80 denotes .080" x .080"
F40 denotes .040" x .040"
FA80 denotes .080" x .120"
FB40 denotes .040" x .080"
F120 denotes .120" x .120"
Thickness of THERMOFLAKE in microns
Specify 1 for 25 microns (.001") thick.
Specify 2 for 50 microns (.002") thick.
Type of mounting (when applicable). See Figures A500, A501, A502, A505
ORDERING EXAMPLES:
1. A 50 micron thick THERMOFLAKE with a cross section of
1mm x 1mm, mounted on a TO-5 header (mounting A500)
and having a resistance of 1 megohm ±25% at 25°C would
be specified as A500-2F40M105N. If a coated germanium
filter were required, the part number would be:
A5002F40M105N-GF.
2. An unmounted THERMOFLAKE having a thickness of 25
microns, a cross section of 2mm x 2mm, double adjacent
leads and a resistance of 500k ohms ±20% at 25°C would
be specified as 1F80D504M.
BOWTHORPE THERMOMETRICS
Crown Industrial Estate, Priorswood Road
Taunton, Somerset TA2 8QY UK
Tel +44 (0) 1823 335200
Fax +44 (0) 1823 332637
THERMOMETRICS, INC.
808 US Highway 1
Edison, New Jersey 08817-4695 USA
Tel +1 (732) 287 2870
Fax +1 (732) 287 8847
KEYSTONE THERMOMETRICS CORPORATION
967 Windfall Road
St. Marys, Pennsylvania 15857-3397 USA
Tel +1 (814) 834 9140
Fax +1 (814) 781 7969
