I. Specification Comparison

II. Appearance Observations

III. Manufacturing Processes

IV. Characteristic Analysis

V. Summary

Benchmark of Metal Strip

Current Sensing Resistors

I. Specification Comparison

Company

Model WMCS series WSL series LR series RL series RLM series

Power

Rating

2W (1mW≦R≦100mW) 2W (R≦10mΩ) 2W (0.5mΩ≦R≦75mΩ) 2W (R≦2mΩ) 2W (R≦10mW)

1W (1mW≦R≦200mW) 1W (R>10mΩ) 1W (0.5mΩ≦R≦100mΩ) 1W (R>2mΩ) 1W (R>10mW)

TCR±50ppm/°C

(1mW≦R≦200mΩ)

275ppm/°C

(R≦2.9mΩ)

50ppm/°C

(0.5mΩ≦R≦3mΩ)

200ppm/°C

(R≦2.9mΩ)

275ppm/°C

(R≦2mΩ)

150ppm/°C

(2.9mΩ<R≦4.9mΩ)

-25ppm/°C

(3.1mΩ<R≦6.9mΩ)

100ppm/°C

(3mΩ<R≦10mΩ)

100ppm/°C

(2mΩ<R≦10mΩ)

110ppm/°C

(4.9mΩ<R≦6.9mΩ)

-15ppm/°C

(7mΩ≦R>10mΩ)

50ppm/°C

(R>10mΩ)

75ppm/°C

(R>10mΩ)

75ppm/°C

(R>6.9mΩ)

Resistance

Range1mΩ~200mΩ 1mΩ~500mΩ 0.5mΩ~100mΩ 1mΩ~50mΩ 1mΩ~100mΩ

Operating

Temp. Range-55°C~+170°C -65°C~+170°C -65°C~+275°C -55°C~+170°C -55°C~+170°C

Company

Top View

Bottom View

Side View

II. Appearance Observations

Metal foil/substrate

laminationCu electrode

formation

Resistance

trimming

Over-coating Marking Cu/Ni/Sn Plating

III. Manufacturing Processes

Wellcomp WMCS series

III. Manufacturing Processes

Vishay WSL series

NiCr foil Cu electrode welding Trimming Over-coating

Marking Terminal plating

010Resistance

formationMolding Marking

Cu electrode

combination

III. Manufacturing Processes

GTC LR series

010

Terminal Plating

010

III. Manufacturing Processes

Cyntec RL series

Substrate Metal foil/substrate

lamination

Trimming

Over-coating Marking Terminal plating

III. Manufacturing Processes

TA-I RLM series

Resistance

formationMolding Marking Cu plating

Cutting and Sn

platingSorting

IV. Characteristic Analysis

TCR (Temperature Coefficient of Resistance)

Company

ItemWMCS2512

R010

WSL2512

R010

LR2512

R010

RL3264

R010

RLM2512

R010

R1 at 25°C (mW) 9.98 9.96 9.97 10.02 10.02

R2 at 125°C (mW) 9.97 9.98 9.96 10.03 9.99

TCR (ppm/°C) -10.02 20.08 -10.03 9.98 -29.94

STOL (short time over load) test

Test condition：

Power：5W Current：22.4A Loading Time：5 seconds

IV. Characteristic Analysis

Power 5W

Company

Res

ista

nce

Va

ria

tio

n

MAX 0.02% 0.04% 0.03% 0.08% 0.03%

MIN 0.01% 0.01% 0.01% 0.02% 0.01%

AVG 0.011% 0.023% 0.02% 0.05% 0.013%

IV. Characteristic Analysis

STOL (short time over load) test

Test condition：

Power：10W Current：31.6A Loading Time：5 seconds

Power 10W

Company

Res

ista

nce

Va

ria

tio

n

MAX 0.06% 0.32% 0.28% 0.26% 0.15%

MIN 0.01% 0.11% 0.13% 0.02% 0.02%

AVG 0.038% 0.243% 0.178% 0.133% 0.092%

Device Surface Temperature

Test Condition： Current:10A Loading Time:10min

Wellcomp Vishay

CyntecTA-I

IV. Characteristic Analysis

GTC

V. Summary

Company Wellcomp Vishay GTC Cyntec TA-I

ModelWMCS

seriesWSL series LR Seroes RL series RLM Series

Construction

Metal foil on ceramic

substrate

Combination of the

metal foil and the

electrode material

Combination of the

metal foil and the

electrode material

Metal foil on

ceramic substrate

Metal foil body with

copper plating

electrodes

Advantage

1.High chip size

ability

(From 0805~2512)

2. Low device

working temperature

3. Lead-free product

4. High thermal

stability

1. Lower terminal

resistance

2. Lead-free

product

1. Lead-free

product

2. Lower terminal

resistance

1. Low device

working

temperature

2. Lead-free product

3. High device

thermal stability

1. Well mass

production ability

2. Lead-free product

Disadvantage

1. Not well known

yet

1. High material

cost

2. High human

source request

for the assembling

1. High material

cost

2. High human

source request

for the assembling

3. Weak overcoating

1. High process

control cost

2. Longer lead time

1. High device

working temperature

2. Poor soldering

especially at small

size device.