NTC Thermistor for Temperature

Sensor in Battery Pack

Technical Report

2011. 11. 1.2011. 11. 1.

LATTRONLATTRON

Requirement for Battery Pack

pack

thermistor

cell

PCB

Low profileStrong enough to touch Thin head

Strong overcoat

Strong enough to bendHard to be scratchedon packing or handling

Strong lead

High insulation

on packing or handling

Strong enough to fold

Easy for soldering

Regular pitch

Easy for soldering

Comparison with the Products in the Market

4 types of NTC thermistor are suggested for battery pack

Head strength, lead strength, and dielectric strength are main factor for selection.

TypeInsulated wire

typeEnamel wire type

Film type(LNJT103F0)

FG1(LNFK103F)

Head strength, lead strength, and dielectric strength are main factor for selection.

Lead material AWG30 / Epoxy Cu / Enamel Alloy42/Polyimide Cu-Sn/Polyimide

Head profile D 2.3mm D 2.0mm T 0.50mm typ T 0.50mm typ

Lead wire D 0.8mm D 0.2mm T 0.25mm T 0.25mm

Pitch regular irregular fixed fixed

AppearanceAppearance

Thermal Reliability of Film type NTC Thermistor

Reliability

0.8%

1.0%

△R/R25

0.2%

0.4%

0.6%

0.8%

-0.4%

-0.2%

0.0%

0.2%

0 200 400 600 800 1000

Dry Heat Thermal Shock

-1.0%

-0.8%

-0.6%

time (hr)

Dry Heat Thermal Shock

Damp Heat Cold

time (hr)

Resistance change of all types are within ±1.0% (allowance) .

Response on Surface Temperature Variation

Variation of surface temperature is measured.

Response time is defined as thermal time constant, which is dependent on the structure

and shape.

LNF series shows the 2nd good response activity.

model TTC (sec) remarkmodel TTC (sec) remark

LNJT103F3 3.3 Film

LNFK103F 4.6 FG1

ET-CP0.16 7.5 Enamel

AT4-AWG30 11.1Epoxywire

Durability on Mechanical Pressure

Static pressure is applied on the head with a constant speed.

Every type shows its characteristic behavior.

LNF series (FG1) shows the strongest with least variation.

From Left

LNFK - FG1 typeLNFK - FG1 type

103F0 - Film type

103F3 – Silicon coated

103JT – Japan103JT – Japan

AT4 - Wire type

ET - Enamel type

Model Average (N) Maximum (N) Minimum (N)

LNFK103F (FG1) 343 343 343

LNJT103F0 170 217 94

LNJT103F3 280 343 134

Best reliabilityBest reliabilityamongamong

comparatives.comparatives. LNJT103F3 280 343 134

SM103JT 275 343 137

AT4-AWG30- M 267 343 197

ET-CP0.16 - M 68 113 24

SM103JT, AT4-AWG30-M, and ET-CP0.16-M are Japanese product.

comparatives.comparatives.

SM103JT, AT4-AWG30-M, and ET-CP0.16-M are Japanese product.

Lead Frame Bending Test

Bending Test Setup

• Folding endurance tester

• Bending to ±90° 로 bending, Stop

Result Summary

• Stable strength is shown at LTR’s, with average

16.5.• Bending to ±90° 로 bending, Stop

bending if Open is measured.

• Tensile load : 1N

• Number of bending is counted

16.5.

• Bending strength is weaker in the region without

film, showing strongest at LTR’s sample.

• Number of bending is counted

before failure

30

35

TheAverageNumberofBending@Openfail

16.5

19.520

25

TheAverageNumberofBending@Openfail

DUT

electricconnection

16.5

11

5

10

15

TheAverageNumberofBending@Openfail

±90° bending

tensileload

connection

0

5

LTR Semitec Joinset

TheAverageNumberofBending@Openfail

Prod-A Prod-B±90° bending

Vendor name

Comparison of Film Property

Polymer film NTC chipPolymer film NTC chip

Solder

Adhesive

lead frame

Item Lattron Prod-A

LTR provides halogen-free product.

Item Lattron Prod-A

Structure Both faces are made of PI film

(Halogen-free)

Surface : PI + silicone adhesive

Bottom : PE + silicone adhesive

Properties Adhesion good

High reliability under humidity

Week adhesion

Acceptable reliability under humidity

Film peeling testFilm peeling test

Film Peel Test

Shape after failure Graphic behavior value

0.38kgf

Higher peel strength is shown at LTR’s than Prod-A

LTR

0.38kgf

broken

Prod-A

0.04kgf

Peeled offProd-A Peeled off

Electrical Reliability of LTR’s 2 Series

Test item Test condition Characteristics Drift

Dry Heat TestElements are placed in a oven of temp.at 90 ± 5℃ for 1000 (+48, -0)hr.

(△R, △B) after testare less than ± 1%.

Test ConditionTest Condition

Dry Heat Testat 90 ± 5℃ for 1000 (+48, -0)hr. are less than ± 1%.

Damp Heat TestElements are placed in a chamber of temp. at85 ± 3℃ and 85 ± 3 %RH for 1344 (+48, -0)hr.

(△R, △B) after testare less than ± 1%

Dry heat test (Hrs) 0 100 500 1000

LNJT103F0 0.00% 0.20% 0.40% 0.40%

Resistance ChangeResistance Change

LNJT103F0 0.00% 0.20% 0.40% 0.40%

LNFK103F (FG1) 0.00% 0.22% 0.32% 0.35%

Damp heat test (Hrs) 0 100 672 1344

LNJT103F0 0.00% 0.16% 0.14% 0.17%

LNFK103F (FG1) 0.00% 0.15% 0.15% 0.16%

Reliability is tested with 20 samples for each model.

Resistance change after dry heat and damp heat for 1000h is almost the samefor both film(LNJT) and FG1(LNF) type.

Conclusion

LNF series shows the best mechanical stability.

Electrical properties show almost the same those of film.

LNF series is best fit for temperature sensor of rechargeable battery. LNF series is best fit for temperature sensor of rechargeable battery.

SummarySummary

item unitinsulated wire

typeCP wire type

film type(LNJT103F0)

FG1(LNFK103F)

failure on mec’l shock mJ > 18 5 10.6 > 18

SummarySummary

failure on mec’l shock mJ > 18 5 10.6 > 18

failure on pressure N > 200 > 24 > 130 > 340

Thermal time constantfor surface Sec (typ) 11.1 7.5 3.3 4.6for surfacetemperature

Sec (typ) 11.1 7.5 3.3 4.6

durability on bending cycle (min) 20 6 20 20

RoHS ◎ ◎ ◎ ◎RoHS ◎ ◎ ◎ ◎

Halogen free ◎ ◎ ◎ ◎