C-THERM TCi, Operator'S Manual, Page: 110 / 138

TCi Operator Manual
104
C m
m
T
 

/ 1
1
'
in V/

s (31)
Is the corrected slope for temperature T.
For example, suppose a material under test has 1/m
25
=150

s/V and 1/m
70
=160

s/V , and the k
calibration has these parameters: Slope =100

smK/WV , Intercept =90

s/V and m
*
=0.0015 V/

s .
Calculation of k at 25

C is:
035 . 1
100
90 55 . 193
100
90
005166 . 0
1
100
90
0015 . 0 150 / 1
1
1
*
25











Slope
Intercept
m m
k
W/mK .
Calculation of k at 70

C is:
From the 1/m Vs. temperature graph above, C
25
=54 and C
70
=62. Hence

C =+8

s/V .
152
1
8 160
1
/ 1
1
/ 1
1
'
70



 

 

C m C m
m
T
0685 . 1
100
90 85 . 196
100
90
00508 . 0
1
100
90
0015 . 0 152 / 1
1
1
* '
70











Slope
Intercept
m m
k
W/mK .
Without correction the calculated k would be:
20 . 1
100
90 52 . 210
100
90
00475 . 0
1
100
90
0015 . 0 160 / 1
1 1
*
70











Slope
Intercept
m m
k
W/mK .
Notes:
1. For k calculation, the C(T) must correspond to the applicable power level.
2. This correction is most effective for low k materials. For high k materials, the correction
may be negligible.
9.7 Error analysis
9.7.1 General
There are in general 2 types of errors (sometimes called uncertainty) – offset and variation. Offset
errors affect the accuracy of the measurement while the variation affects the repeatability.