A Subsidiary of
TT electronics plc
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.
Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA
Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com
LRMA
Low Resistance Metal Alloy
Current Sense Resistor
LRMA Series April 2010 Sheet 1 of 5
IRC
Type
Footprint Power rating
at 70°C (Watts)
Standard Resistance Values
(m)1
TCR
(±ppm/°C)
Tolerance
(±%)
Insulation
Resistance (MΩ)
Version - M2 (Manganese-Copper Alloy)
LRMA-M 2512 2 5, 10 100 1, 2, 5 100
20 75
1 30, 40 75
1206 1 5, 10, 100
15, 20, 25, 30 75
Version - N
LRMA-N 0815 1 1, 6, 8, 10, 15, 20, 25, 30 100 1, 2, 5 100
Version - P
LRMA-P 2512 3 3, 5, 10 100 1, 2, 5 100
11, 15, 20, 25, 30, 40, 50, 80, 100 75
Version - T (Copper-Nickel Alloy)
LRMA-T 2512 2 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10 100 1, 2, 5 100
1 11, 12, 15, 18, 20, 25, 30, 33, 40, 50 75
Robust metal strip able to withstand high temperature and high current.•
Low TCR and Inductance•
Resistance Range from 1 mΩ to 100 mΩ•
Power ratings from 1W to 3W in 0815, 1206, and 2512 chip size•
Designed for current sense circuits in power electronic and automotive •
systems
RoHS compliant and Halogen Free•
Electrical Data
Notes:
1Non-Listed resistance values available (contact factory). 2Constructed of Manganese Copper alloy, which reduces thermal emf, and is distinguished by a
green mold compound.
Test Item Reference Test Condition Test Limits
High Temperature Exposure MIL-STD-202 method 108 + 125°C 1000 hrs < ± 0.5%
Temperature Cycling JESD22 method JA-104 1000 cycles (-55°C to +125°C) < ± 0.5%
Bias Humidity MIL-STD-202 method 103 1000 hrs @ 85°C / 85% RH < ± 0.5%
Operational Life MIL-STD-202 method 108 Steady State, ambient 70°C @ rated power < ± 0.5%
Mechanical Shock MIL-STD-202 method 213 100 g’s < ± 0.5%
Vibration MIL-STD-202 method 204 5 g’s for 20 min, 10 - 2000 Hz, 12 cycles 3 planes < ± 0.5%
Resistance to Solder Heat MIL-STD-202 method 210 Condition B: No pre-heat < ± 0.5%
Solderability J-STD-002 245°C ± 5°C solder, 2 ± 0.5 sec > 95% coverage
Terminal Strength AEC Q200-006 Force of 1.8 kg for 60 seconds < ± 0.5%
Board Flex AEC Q200-005 2 mm defl ection (min) < ± 0.5%
Short Time Overload 5 X rated power for 5 sec < ± 0.5%
Environmental Data
Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA
Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com LRMA Series April 2010 Sheet 2 of 5
D
W
T
L
T
L
D
W
Package Resistance
Value (m)2
LWT D
LRMA - M
2512 5 - 40 6.4 ± 0.2 3.2 ± 0.2 0.6 ± 0.2 0.9 ± 0.2
1206 5 - 20 3.2 ± 0.2 1.6 ± 0.2 0.6 ± 0.2 0.5 ± 0.3
LRMA - N
0815 3 - 20 3.8 ± 0.3 2.1 ± 0.3 0.7 ± 0.2 0.5 ± 0.2
LRMA - P
2512 3 - 100 6.4 ± 0.2 3.2 ± 0.2 0.7 ± 0.2 0.9 ± 0.2
LRMA - T
2512 ≤ 2 6.4 ± 0.2 3.2 ± 0.2 0.6 ± 0.2 2.0 ± 0.2
> 2 - 50 0.9 ± 0.2
Physical Data
Note:
1 Dimensions are for reference only and are expressed in mm.
2 Resistance range listed is the full possible range for the product family. Consult factory for offerings within this range, but not listed on
Sheet 1.
Version - M, P, and T Version - N
Sensing Trace
a
Lb
Circuit Trace
Package Resistance
Value (m)2
a1b1L1
LRMA - M
2512 3 - 50 4.0 2.1 4.1
1206 5 - 20 1.8 1.9 1.4
LRMA - N
0815 3 - 20 7.9 1.5 0.9
LRMA - P
2512 3 - 100 4.0 2.1 4.1
LRMA - T
2512 1 - 2 4.0 3.1 1.3
3 - 50 4.0 2.1 4.1
Electrical Connections
Note:
1 Dimensions are for reference only and are
expressed in mm.
2 Resistance range listed is the full possible
range for the product family. Consult factory
for offerings within this range, but not listed on
Sheet 1.
Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA
Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com LRMA Series April 2010 Sheet 3 of 5
Construction
Version - M, P, and T Version - N
Resistive Alloy
UL-94 V0 grade
moulding compound
Copper
Electrode
Ni / Sn
Plating
A low TCR resistive alloy is coated with a molding compound that enables the part to be suitable for wave and IR refl ow
methods by controlling the solder attachment area. Copper electrode reduces resistance measurement sensitivity that
can result from connection directly to the resistive alloy. Nickel / Tin plating provide a solder compliant surface. LRMA
version M is green in color and constructed of Manganese Copper alloy.
Power Derating
Note:
The power derating curve is a guidance based on a con-
servative design model. The LRMA is a solid metal alloy
construction that can withstand signifi cantly greater oper-
ating temperatures than the conservative model permits.
The protective coating will operate up to 260°C while the
alloy can withstand in excess of 350°C. Therefore, the
system thermal design will be the most signifi cant design
parameter due to the heat limitations of the solder joint.
70 170
100
50
0
% Of Rated Power
Ambient Temperature (°C)
0
LRMA-N
20 m at 1 Watts
LRMA-P
10 m at 3 Watts
LRMA-M
20 m at 2 Watts
Thermal Images
The above images are based on a standard test circuit board constructed of a four layer FR4 material with 2-ounce
outer layers and 1-ounce inner layers, which is typical of many industry designs. Each of the above images is in ambient
temperature conditions with no air fl ow. Contact IRC for more details or for other thermal image test data for specifi c
resistance values and power levels.
Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA
Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com LRMA Series April 2010 Sheet 4 of 5
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 refl ow depends on package
thickness and volume. The use of convection
refl 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 profi les
defi ned in Table 1, 2 and refl ow profi 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 classifi 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)
specifi ed for the refl ow profi 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 (TP) See Table 1 See Table 2
Time within 5°C of actual Peak Temperature (tp)210 - 30 seconds 20 - 40 seconds
Ramp-down Rate 6°C / second max. 6°C / second max.
Time 25°C to Peak Temperature 6 minutes max. 8 minutes max.
Sn-Pb Eutectic and Pb-Free Reflow Profiles
Time
Temperature
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
Wire and Film Technologies Division • 4222 South Staples Street • Corpus Christi Texas 78411 USA
Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com LRMA Series April 2010 Sheet 5 of 5
Packaging Quantity
Series Emboss Plastic
Tape
2512 4,000
0815 4,000
1206 5,000
Ordering Data
Specify type, resistance, tolerance, ROHS compliance and packaging.
Example: Metal Element Current Sense Resistor, 1-watt, 10 mΩ resistor.
IRC Type
Version
M, N, P, and T
Power Rating
(refer to spec table)
Package Size
Resistance Value (EIA 4-digit code)
Example: 0.010 Ω = R010
Tolerance (EIA format)
F = 1%, G = 2%, J = 5%
RoHS - Compliance
LF = RoHS compliant Construction
Packaging
SLT = Standard Lead Tape
LRMA 3 2512 R010 F LF SLTSample Part No. N
W
E
F
ψ D0
P1 P2
P0
direction of unreeling
B
Top Tape
Resistor
Emboss Tape
Tψ D1 1.4Min.
A
Size A B W E F P0P1P2 D0T
2512 3.6±0.2 6.9±0.2 12±0.2 1.75±0.1 5.5±0.05 4.0±0.05 4.0±0.1 2.0±0.05 1.5+0.1, -0 0.85±0.15
0815 2.6±0.2 4.5±0.2 12.0±0.2 1.75±0.1 5.5±0.1 4.0±0.1 4.0±0.1 2.0±0.2 1.55±0.05 1.1±0.1
1206 2.0±0.2 3.6±0.2 8.0±0.2 1.75±0.1 3.5±0.1 4.0±0.1 4.0±0.1 2±0.05 1.5+0.1, -0 0.84±0.1
Package Tape Specifi cation
Note:
The cumulative tolerance of 10 sprocket hole pitch is ± 0.2 mm.1.
Carrier camber shall not be more than 1 mm per 100 mm through a length of 250 mm.2.
A & B measured 0.3 mm from the bottom of the packet.3.
T measured at a point on the inside bottom of the packet to the top surface of the carrier.4.
Pocket position relative to sprocket hole is measured as the true position of the pocket and not the pocket hole.5.
