Open Air Sense Resistors
Metal Alloy Strip
OARS Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
© TT electronics plc
09. 11
· Greater than 1 Watt rating for 2512 pad design
· Zero ohm jumper available, OARSZ
· Economical low value SMT
· Resistance values 2mΩ to 50mΩ
· ±1% or ±5% tolerance
· Open air design provides cooler operation
General Note
IRC reserves the right to make changes in product specifi cation without notice or liability.
All information is subject to IRC’s own data and is considered accurate at time of going to print.
s3OUTH3TAPLES3TREETs#Orpus Christi TeXAS53!
Wire and Film Technologies Division
Telephone:sFacsimile:s Website: www.irctt.com July 2011 Issue Page 1 of 4
OARS
Open Air Sense Resistors
Metal Alloy Strip
A Subsidiary of
TT electronics plc
s Greater than 1 Watt rating for 2512 pad design
s
sEconomical low value SMT
sResistance values 2mto 50m
s±1% or ±5% tolerance
sOpen air design provides cooler operation
Electrical Data
IRC Type Power Rating
(watts)
Available Resistance
(ohms)
OARS-1 1W @ 70°C .002, .003, .004, .005, .010, .015
.020, .022, .025, .030, .040, .050
1
Non-Standard un-listed resistance values can be made available, subject to engineering charges and/or minimum order requirements.
Physical Data
Dimensions (Inches and (mm))
IRC
Type WDTHL
OARS-1 0.440 ±0.015
(11.18 ±0.381)
0.120 ±0.030
(3.05 ±0.762)
0.093 ±0.010
(2.36 ±0.254)
0.190 ±0.030
(4.83 ±0.762)
0.125 ±0.015
(3.175 ±0.381)
OARS-1
0.002
0.455 ±.015
(11.56 ±.381 )
0.150 ±0.030
(3.51 ±0.762)
0.093 ±0.010
(2.36 ±0.254)
0.185 ±0.030
(4.70 ±0.762)
0.140 ±0.015
(3.56 ±0.381)
OARS-1
0.003
0.440 ±.015
(11.18 ±.381 )
0.138 ±0.030
(3.51 ±0.762)
0.093 ±0.010
(2.36 ±0.254)
0.180 ±0.030
(4.83 ±0.762)
0.125 ±0.015
(3.175 ±0.381)
Features:
s3UPErior thermal expansion cycling
s&LAMEPROOF
s)NDUCTANCELESSTHANNANOHENries
s,EADfl exible for thermal expansion
Applications:
s#URRENTSENSING
s&eedback
s,ow inductance
s3URGEANDPULSE
sAC applications (please contact the factory)
,
H
W
0.126
0.369
0.121 0.121
0.127
D
T
Recommended Landing Pad Size
Zero ohm jumper available, OARSZ
Open Air Sense Resistors
Metal Alloy Strip
OARS Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
© TT electronics plc
09. 11
Wire and Film Technologies Division
Telephone:sFacsimile:s Website: www.irctt.com
July 2011 Issue Page 2 of 4
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OARS
Open Air Sense Resistors
Metal Alloy Strip
25 60 95 130 165 195 225
2.5
2.0
1.5
1.0
0.5
0.0
Ambient Temperature (°C)
Power Rating (watts)
Power Derating Curve
Environmental Data
m51 >m51 - m4m3 - m2 :cepS tseT
TCR +125 to -55°C 240ppm 40ppm 40ppm
Thermal Shock < 0.75% < 0.75% < 0.75%
High Temperature Exposure 125°C < 1.75% < 0.5% < 1.0%
Temperature Cycling: -40 to +125°C < 1.0% < 1.0% < 0.75%
Operational Life < 2.0% < 1.0% < 1.0%
Baised Humidity < 0.75% < 0.5% < 0.5%
Mechanical Shock < 1.5% < 1.0% < 1.0%
Vibration < 1.0% < 1.0% < 1.0%
Moisture Resistance < 1.0 < 2.5% < 2.0
Terminal Strength Meets JIS-C-6429
Solvent Resistance Meets MIL-STD-202 Method 215
Solderability Meets J-STD-002 Method B
Note:
The power derating curve is a guidance based on a con-
servative design model. The OARS is a solid metal alloy
construction that can withstand signi� cantly greater operat-
ing temperatures than conservative design models permit.
The resistive alloys can withstand temperatures in excess
of 350°C. Therefore, the system thermal design is a more
signi� cant design parameter due to the heat limitations of
solder joints and/or circuit board substrate materials. Refer to
additional information below.
The thermal image (not a simulation) to the left is of an OARS
10 m running at 2 Watts, which exceeds the 1 Watt conser-
vative model. Notice the hotpsot is nearly 200°C, but the sol-
der joint is approximately 65°C (FR4 is rated for 130°C). The
unique construction of the OARS isolates the hotspot from
the circuit board material preventing damage. Additionally,
the thermal energy is dissipated to the air instead of being
conducted into the circuit board potentially causing a nearby
power component to exceed its rating.
The standard test circuit board consists of a four layer FR4
material with 2 ounce outer layers and 1 ounce inner layers,
which is typical of many industry designs. Contact IRC for
more details or for other thermal image test data for speci� c
resistance values and power levels.
AEC Q200
Reference Documents: MIL-STD-202
OARS R005 Thermal Image @ 2 Watts
Ambient conditions, No forced air.
Open Air Sense Resistors
Metal Alloy Strip
OARS Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
© TT electronics plc
09. 11
Wire and Film Technologies Division
Telephone:sFacsimile:s Website: www.irctt.com
July 2011 Issue Page 3 of 4
Note:
The high pulse surge capability of the OARS parts is
attributed to the solid metal alloy construction. In many
applications the cross-section of the OARS is greater
than the cross-section of the board traces connecting
the parts to the circuit board.
Cross-Sectional area ranges from approximately 650
mils to 3600 mils.
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OARS
Open Air Sense Resistors
Metal Alloy Strip
0 10 20 30 40 50 60
70
60
50
40
30
20
Resistance (milli ohms)
Joules (watts-second)
Pulse/Surge Chart
0
10
G
B
C
AF
E
D
Sample Part No.
IRC Type
OARS1
Power Rating in Watts
Resistance Range (ohms)
Tolerance
F = ±1%, G = ±2%, J = ±5%
Ordering Data
OARS1 R005 J LF
Tape Specifi cations
Dimensions (Inches and (mm))
IRC
Type ABCD E F G
OARS 0.17 ±0.003
(4.32 ±0.08)
0.461 ±0.003
(11.7 ±0.08)
0.945 ±0.010
(24.0 ±0.30)
0.453 ±0.004
(11.5 ±0.10)
0.069 ±0.004
(1.75 ±0.10)
0.315 ±0.004
(8.0 ±0.10)
0.157 ±0.004
(4.0 ±0.1)
RoHS Indicator
LF indicates RoHS compliance
Open Air Sense Resistors
Metal Alloy Strip
OARS Series
www.bitechnologies.com www.irctt.com www.welwyn-tt.com
General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
© TT electronics plc
09. 11
Wire and Film Technologies Division
Telephone:sFacsimile:s Website: www.irctt.com
July 2011 Issue Page 4 of 4
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OARS
Open Air Sense Resistors
Metal Alloy Strip
Note 1: Package volume excludes external
terminals (balls, bumps, lands, leads) and/or
non-integral heat sinks.
Note 2: The maximum component temperature
reached during re� ow depends on package
thickness and volume. The use of convection
re� ow processess reduces the thermal gradients
between packages. However, thermal gradients
due to differences in thermal mass of SMD pack-
ages may still exist.
Note 3: Components intended for use in “lead-
free” assembly process shall be evaluated using
the “lead-free” peak temperature and pro� les
de� ned in Table 1, 2 and re� ow pro� le whether
or not lead-free.
Tabel 1: SnPb Eutectic Process -
Package Peak Refl ow Temperatures
Package
Thickness Volume mm3 < 350 Volume mm3 ≥ 350
< 2.5 mm 240 +0/-5°C 225 +0/-5°C
≥ 2.5 mm 225 +0/-5°C 225 +0/-5°C
Tabel 2: Pb-free Process -
Package Peak Refl ow Temperatures
Package
Thickness
Volume mm3
< 350
Volume mm3
350 - 2000
Volume mm3
> 2000
< 1.6 mm 260°C * 260°C * 260°C *
1.6 mm - 2.5 mm 260°C * 250°C * 245°C *
≥ 2.5 mm 250°C * 245°C * 245°C *
* Tolerance: The device manufacturer/supplier shall assure process compat-
ibility up to and including the stated classi� cation temperature at the rated MSL
level.
Note 1: All temperatures refer
to topside of the package,
measured on the package
body surface.
Note 2: Time within 5 °C of
actual peak temperature (tp)
speci� ed for the re� ow pro� les
is a “supplier” minimum and a
“user” maximum.
Profi le Feature Sn-Pb Eutectic
Assembly
Pb-Free
Assembly
Average Ramp-up rate (Tsmax to Tp) 3°C / second max. 3°C / second max.
Preheat
- Temperature Min (Tsmin)
- Temperature Max (Tsmax)
- Time (Tsmin to Tsmax) (ts)
100°C
150°C
60 -120 seconds
150°C
200°C
60 -180 seconds
Time maintained above
- Temperature (TL)
- Time (tL)
183°C
60 - 150 seconds
217°C
60 - 150 seconds
Peak Temperature (TP2 elbaT eeS1 elbaT eeS)
Time within 5°C of actual Peak Temperature (tp)210 - 30 seconds 20 - 40 seconds
.xam dnoces / C°6.xam dnoces / C°6etaR nwod-pmaR
Time 25°C to Peak Temperature 6 minutes max. 8 minutes max.
Sn-Pb Eutectic and Pb-Free Reflow Profiles
Time
erutarepmeT
Critical Zone
TL to TP
Ramp-down
Ramp-up
t 25°C to Peak
TP
TL
Tsmax
Tsmin
ts
Preheat
tL
25
tP
* Based on Industry Standards and IPC recommendations
IRC Solder Refl ow Recommendations