Z Series (Z Foil)
TABLE 3 – ENVIRONMENTAL PERFORMANCE COMPARISON
MIL-PRF-ꢁꢁ18.
CHAR J
Z SERIES
TYPICAL ∆R
Z SERIES
MAXIMUM ∆R(1)
Test Grou
Thermal shock, 5× (–65°C to +150°C)
Short time overload, 6.25× rated power
I
0.2%
0.2%
0.002% (20 ppm)
0.003% (30 ppm)
0.01% (100 ppm)
0.01% (100 ppm)
Test Grou II
Resistance temperature characteristics
Low temperature storage (24 h at –65°C)
Low temperature operation (45 min, rated power at –65°C)
Terminal strength
25 ppm/°C
0.15%
0.15%
0.2 ppm/°C
see table 1
0.002% (20 ppm)
0.002% (20 ppm)
0.002% (20 ppm)
0.01% (100 ppm)
0.01% (100 ppm)
0.01% (100 ppm)
0.20%
Test Grou III
DWV
0.15%
≥104 MΩ
0.10%
0.002% (20 ppm)
0.01% (100 ppm)
≥104 MΩ
0.01% (100 ppm)
0.02% (200 ppm)
Insulation resistance
Resistance to solder heat
Moisture resistance
0.005% (50 ppm)
0.010% (100 ppm)
0.40%
Test Grou IV
Shock
Vibration
0.2%
0.2%
0.002% (20 ppm)
0.002% (20 ppm)
0.01% (100 ppm)
0.01% (100 ppm)
Test Grou
V
Life test at rated power/+125°C
2 000 h
10 000 h
0.5%
2.0%
0.005% (50 ppm)
0.015% (150 ppm)
0.015% (150 ppm)
0.050% (500 ppm)
Test Grou Va
Life test at 2× rated power/+70°C, 2 000 h
0.5%
2.0%
0.005% (50 ppm)
0.02% (200 ppm)
0.015% (150 ppm)
0.05% (500 ppm)
3 ppm/V
Test Grou VI
High temperature exposure (2 000 h at +175°C)
Test Grou VII
Voltage coefficient
5 ppm/V
(1) Measurement error allowed for ∆R limits: 0.01 Ω
STANDARD OPERATIONS AND
TEST CONDITIONS
LONG-TERM STABILITY
Some process controls are not very critical but many,
many are – particularly when a process is operating near
a tipping point where it could get out of control quickly if
not well monitored.
A0 Standard Test O erations
By 100% Inspection:
• TCR
In process control applications, entire production batches
have been lost or suffered reduced reliability when
critical parameters were not kept within narrow limits.
One thing that can cause this to happen is changes
in the precision resistor over time. Reference points in
the control process thus become less and less reliable.
Repeatability of the process from batch to batch begins
to drift. The process is changing while the monitors
appear to be holding it within specified limits because the
sense resistor is producing a different output voltage than
it was in previous runs for the same sensor output. So the
process appears to be under control when, in reality, it is
experiencing an undetected drift.
• Short-time overload (6.25× rated power for 5 s)
• Resistance – tolerance check
• Visual and mechanical
By Sample Inspection:
• Environmental tests per table 3 on a quarterly basis
to establish performance by similarity
B0 Test Conditions
• Lead test point: 0.5 in (12.7 mm) from resistor body
• Temperature: +23°C 2°C
• Relative humidity: per MIL-STD-202
Long-term stability is thus one of the considerations that
drive the selection of which resistor technology to use in
the application.
But the typical permanent resistance drift of a Bulk Metal
Foil resistor is less than 60 ppm (0.006%) after 10 years
running at 0.1 W at 70°C.
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4
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foil@vpgsensors.com
Document No.: 63187
Revision: 01-Nov-2016