High thermally-conductive product for automotive electronic assembly applications

DOWSIL™-TC-2035-CV-Adhesive
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Thermally-conductive composites: DOWSIL™ TC-2035 CV Adhesive

This new adhesive is a high thermally-conductive product with low temperature, fast cure and outstanding room-temperature shelf-life stability for automotive electronic assembly applications. This technology enables low-carbon mobility.

 

Key benefits:

  • High thermal conductivity 3.3 W/m.K
  • Low bond line thickness
  • High elongation at break ~50%
  • Easy dispensing
  • Temperature curing at 115°C/15 minutes
  • Primerless adhesion on selected substrates
  • Long-shelf life of 12 months at or below 35°C
  • Low volatile content < 100 ppm

 

Automotive applications:

  • ADAS (Advanced Driver Assistance Systems)
  • ECU Assembly
  • Power electronics
    • Converter/inverter
    • OBC

 

Material properties comparison

Property DOWSIL
TC-2035 CV Adhesive
DOWSIL™
TC-2035 Adhesive
Benefits
Color Reddish brown Reddish brown
Thermal conductivity (W/mK) 3.3 3.0 High thermal conductivity
Specific gravity – cured 3.00 03.07
Initial extrusion rate (g/min) Part A: 33
Part B: 52
Part A: 43
Part B: 58
High dispense rate – higher throughput
Shelf life (months) 12 6 Lower scrap
Storage condition ≤ 35°C ≤ 25°C Lower scrap and energy consumption
Pot life (hour) 3.5 5 Easier processing
Durometer (Shore D) 33 38
Tensile strength (MPa) 3.7 3.1 Higher reliability
Elongation (%) 50 55 Flexible joints, less material needed
Adhesion failure mode (%) ≥90% Cohesive
*Al – A5052P, Anodized
≥90% Cohesive
*Al – A1050P
Good primerless adhesion
Lap shear adhesion (MPa) 2.9; *Al – A5052P, Anodized 2.6; *Al – A1050P Stronger adhesion
Cure condition 15 minutes at 115°C 30 minutes at 125°C Faster processing,
lower energy consumption

 

DOWSIL™ TC-2035 CV Adhesive

 

Table 1

Test Property
CTM1 0176 B Two-part
CTM1 0176 B Color:
Part A – White
Part B – Reddish-brown
CTM 0022 B Density: Part A and Part B – 3.0 g/cm3
Mix ratio – 1:1
Heat cure time at 115°C – 15 minutes
Pot life at 25°C – 3.5 hours

tc-2035 cv adhesive example

 

Table 2

Test Property Result
CTM 0793 Hardness, Shore D 33
CTM 1094 C Viscosity at 1 (1/s)
Part A
Part B
350 Pa.s
290 Pa.s
CTM 1094 N Viscosity at 1 (1/s) mixed 345 Pa.s
CTM 1393 Minimum bond line thickness ≤ 95 μm
CTM 0137 Tensile strength 3.7 MPa
CTM 0137 Elongation 50%
CTM 0243 A Adhesion –
Lap shear; Al anondized A5052P
Failure mode–cohesive
2.9 MPa
≥ 90%
CTM 0114 Dielectric strength at 1 mm 22 kV/mm
CTM 1163 Thermal conductivity by transient method 3.3 W/mK
DIN2 51007 Heat capacity, volumetric at 25°C
Heat capacity at 25°C
2.63 MJ/m3K
0.88 J/gK
ASTM3 E 831 Linear CTE (by TMA -50 to 200°C) 93.6 ppm/K

 

Properties of DOWSIL™ TC-2035 CV Adhesive

 

Thermal and electrical properties

  • Thermal conductivity: 3.3 W/mK
  • Dielectric strength: 22 kV/mm
  • Heat capacity at 25°C: 0.88 J/gK
  • Linear CTE (-50 to 200°C): 93.6 ppm/K

tc-2035 cv adhesive example

 

Primerless adhesion on select substrates

DOWSIL™ TC-2035 CV Adhesive achieves cohesive failure on most common aluminum substrates without the use of any primer.

tc-2035 cv adhesive example Primerless adhesion on select substrates

 

 Coefficient of Thermal Expansion (CTE)

tc-2035 cv adhesive example_Coefficient of Thermal Expansion (CTE)_2 tc-2035 cv adhesive example_Coefficient of Thermal Expansion (CTE).

 

 

Silicone curing mechanism

Addition-cure material

  • Low cure initiation temperature with onset between 74.6 and 77.2°C and peak at 77.9 to 80.6°C
  • No cure by-products
  • Minimal shrinkage

tc-2035 cv adhesive Silicone curing mechanism

 

Pot life and curing profile

Pot life profile
Initial 120
minutes
180
minutes
210
minutes
240 minutes
1 (1/s)
Pa-s
323 372 460 566 741
Viscosity change 15% 42% 75% 130%

tc-2035 cv adhesive example_Curing profile

 

Stable viscosity

  • Viscosity of DOWSIL™ TC-2035 CV Adhesive remains completely stable throughout its shelf life
  • Almost non-existent sedimentation or separation

tc-2035 cv adhesive stable viscosity

 

High purity material

Total D4-D6 content below 100 ppm
(Unit: µg/g) D4 D5 D6
Batch 1 18.90 5.40 2.40
Batch 2 20.20 5.50 2.50
Average 19.50 5.45 2.45

 

Ionic species below 5 ppm
Element DOWSIL™
TC-2035 CV Adhesive (1)
DOWSIL™
TC-2035 CV Adhesive (2)
DOWSIL™
TC-2035 CV Adhesive (3)
Cation measurement results
Sodium <2.64 <2.64 <2.64
Potassium <1.13 <1.13 <1.13
Anion measurement results
Fluorine <0.32 <0.32 <0.32
Chlorine <3.33 <3.33 <3.33
Bromine <0.58 <0.58 <0.58

 

Processing

  • Minimum BLT ≤ 95 µm
  • Mixing ratio 1:1
  • Cure profile 15 minutes at 115°C
  • Pot life 3 to 4 hours at 25°C
  • Fast dispensing
    • Extrusion rate Part A: 33 g/min
    • Extrusion rate Part B: 52 g/min

tc-2035 cv adhesive processing

tc-2035 cv adhesive processing

 

Mixing ratio tolerence

Properties Range Initial
mixing ratio
A/B=100/100
Initial
mixing ratio
A/B=115/100
Initial
mixing ratio
A/B=100/115
Viscosity of mixture
1700 ± 500 Pa·s 1734 1629 1555
330 Pa·s ± 150 Pa·s 348 338 332
150 +- 40 Pa·s 152 151 150
Change of viscosity (2 hr) under 20% increase 3 7 3
Thermal conductivity 3.4 W/mK +/- 0.3 W/mK 3.4 3.3 3.3
Tensile strength 2.9 MPa -0.7/+ 1.5 MPa 3.6 3.1 3.8
Tensile properties
elongation at break
55% – 10 /+ 25% 47 56 49
Linear strain limit 5% +- 0.5% 5.2 5.0 5.0
Curing parameters
Specific density 3.00 +/- 0.1 g/cm³ 2.99 2.99 2.99
Shore hardness 28 +/- 10 Shore D 38 33 37
Tensile lap shear strength A5052P
2.3 N/mm² – 0.5 /+ 0.9 N/mm²
03.04 2.56 3.15

 

Overview DOWSIL™ TC-2035 CV Adhesive

DOWSIL™ TC-2035 CV Adhesive_conclusions

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