new thermally conductive polycarbonates for weight and
TRANSCRIPT
covestro.com
New Thermally Conductive
Polycarbonates for Weight
and Cost Savings in
Automotive Applications
J. Lorenzo, Covestro LLC SPE Automotive Composites Conference & Exhibition, 2018 Novi MI
Automotive LED Applications
2
Requiring Thermal Management
Exterior
Lighting
LED Brake
Light /
CHMSL
Interior Lighting and
Electronic
Components
LED
Headlamps,
DRL,
Signature
Lighting
LED Lighting Applications
3
Relevant Lighting Parts
Lens
Reflectors
Heat-sinks
Housings
Thermally Conductive Polymers
4
Benefits
There are many variations of passages of lorem
ipsum available, but the majority suffered
alteration some form
There are many variations of passages of lorem
ipsum available, but the majority suffered
alteration some form
There are many variations of passages of lorem
ipsum available, but the majority suffered
alteration some form
Thermally conductive polymers offer solutions to
thermal management in LED luminaires, housings
and other electrical and electronic applications
Primarily, they enable…
Weight savings through metal replacement in
heat sink applications
integration of functions and reducing the number
of components & secondary operations
gain high dimensional stability with an
amorphous material
Customized Thermal Conductivity and Electrical Insulation
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Comparison of the Makrolon® TC Portfolio
* Volume resistivity >E+15 Ωm, Surface resistivity >E+15 Ω Volume and surface resistivity based on IEC 60093, 23°C, 50% r. h.
TC8030 TC611 TC511 TC110 Property
Electrical Properties
UL 94 Flame Class
UL 746B RTI
UL 746C Rating
Thermal
Conductivity
(in-plane )
ASTM
E1461
23°C (W/m•K)
Standard/
Condition/
Unit
Conductive
V-0 @ 2.0
130
f1
14
8 16
1
Electrically conductive grades
offer a high to medium
thermal conductivity with a
black color appearance.
Electrically insulating grades
offer a moderate thermal
conductivity with a white color
appearance and a smooth
surface.
TC8010
8
Density
Vicat Softening
g/cc
(°C)
1.42
148
1.31
130
1.40
130
1.45
145
1.34
136
(mm)
(°C)
16 22 32 45 46 Spiral flow length Internal @ 2mm
(cm)
Insulating*
HB
New New New
Conductive
V-0 @ 2.0
Conductive
V-0 @ 3.0
Injection
molding
Injection
molding
Injection
molding
Injection
molding
Profile
extrusion
Injection
molding
Profile
extrusion
Process Options
Thermally Conductive (TC) Polycarbonate in LED Applications
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Thermal Conductivity Comparison – Why TC polycarbonate works
LED Temperature vs. Housing Conductivity
Advantages
Less parts
Less assembly steps
Light weight solution
Long-term, reliable heat management
7
New Design Concepts
New Opportunities of Part Integration
Heat sink
+
PCB1)
In-mold
assembly
of PCB1)
+ TIM2) + PCB1)
Al TC611 TC511
1
1) Printed Circuit Board
2) Thermal Interface Material
Advantages as Ex. 1 plus:
1-step process for luminaire housing
Advantages as in Ex. 1-2 plus:
Direct print circuitry
Avoidance of TIM + PCB
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LED Heat Sink Designs with 2K-Molding
Two-Component-Processing to Reduce Complexity and Cost
Further
integration
by 2k-
molding
Heat sink
+
Functional parts
+ TIM + PCB
+ housing parts Al TC611
TC110
Reflector E.g. +
TC611 TC110
Reflector E.g. +
Apply
electrical
layers
2
3
covestro.com
DESIGN CONSIDERATIONS Advantages of Thermally Conductive Polycarbonate
Design Considerations with Thermally Conductive PC
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Low to Higher Powered Applications are Achieveable
10W LED Lamp 200W LED Array
High Bay Light
Traditional LED Housing Design with
Aluminum Heatsink
8 Components
Optimized
Polycarbonate Design
6 Components
18% Lower Cost
Design Considerations
11
Part Consolidation and Integration Potential
Thermal Conductivity & Specific Heat
Natural Convection
Coolant & Flow Rate
Emissivity
Design Considerations
12
Heat Transfer Mechanisms
Multi-Physics Simulation using ABAQUS Computational
Fluid Dynamics (CFD)
Conduction
Convection Passive (Natural Conv)
Active (Fan)
Radiation
Design Considerations
13
Cooling Design Elements
Design efficient cooling features
• Optimize Fins
• Eliminate Flow Obstructions
Slice between fins shows slow or stagnant flow
Design Considerations
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Cooling Design Elements
Cooling Fin Optimization
• Added Fins Improve Thermal Performance
• More fins may not always be better
Design Considerations
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Influence of Increased Surface Area on Thermal Performance
Original Design
Temp (C)
20% Taller Design
Case Temp = 70.7C
(~3C Cooler)
Temp (C)
Case Temp = 73.3C
Design Considerations
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Isotropic v. Anisotropic Thermal Conductivity Modeling
Isotropic Thermal Conductivity
Temp (C) Temp (C)
Case Temp = 72.2C
Anisotropic Thermal Conductivity
10:1 Radial-to-”thru-thickness”
Case Temp = 75.7C
~5% difference in case temperature
Design Considerations
17
Orthotropic Thermal Conductivity Modeling
“Directional”
conductivity exported
to thermal simulation
Mold-filling simulation
to predict local
filler orientations
Design Considerations
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Orthotropic Thermal Conductivity Modeling
Orthotropic Thermal Conductivity
Temp: 105°C Temp: 112.1°C
Temp: 101.8°C Temp: 102.1°C
Isotropic Thermal Conductivity
~7% difference in peak temperature
Negligible
difference
in the
ribs/fins
Extruded Aluminum Heatsink & 3W LED
57.7°C Temp
30g Mass
Optimized Makrolon Design
58.1°C Temp
19g Mass
35% Weight Savings
Benefits of Thermally Conductive Polycarbonate
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Significant Weight Savings at near-Equivalent Perfornance
Extruded Aluminum Heatsink & 3W LED
57.7°C Temp
30g Mass
Optimized Polycarbonate
Design
58.1°C Temp
19g Mass
35% Weight Savings
covestro.com
PROCESSING & JOINING
WITH MAKROLON® TC Thermally Conductive Polycarbonate
General Design Topics for TC Polycarbonate
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Wall Thickness & Rib Thickness
• Nominal thickness of 2.5 mm to 4mm is preferred
• Thicker than standard wall sections may be possible
Thermally Conductive PC 66% Up to 100%
Could potentially be 1:1 for ease of filling
Joining of TC Polycarbonate
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Bonding Techniques
Thermal Techniques
Ultrasonic Welding
Hot Plate Welding
Mechanical or Chemical Bonding
Threaded Fasteners
Adhesive Bonding
Snap Fits
Joining Technique AcceptableAdhesive Bonding Yes
Threaded Fasteners Possibly*
Snap Fits Yes**
Hot Plate Welding No
Ultrasonic Welding No
**Female half only in Makrolon TC polymer
* Limited torque, may require two shot or threaded inserts
Joining of TC Polycarbonate
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Thread Fasteners
• Stripping torque limits the use of threaded
fasteners
• The fastener should pass through the TC material
and anchor into a suitable material
• Threaded inserts or helical thread inserts can
improve torque/pull out performance
1
Joining of TC Polycarbonate
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Adhesive Performance
• Good adhesion strength with common adhesives
o Performance varies depending on the adhesive chemistry
• Adhesive testing available on request
Adhesive Bonding Study with 3M Scotch-Weld1 DP100 Plus
1 Scotch-Weld is a registered trademark of 3M Company 2 Dow Corning is a registered trademark of Dow Corning Corp.
Adhesive Bonding Study with Dow Corning2 7091 (Silicone)
Paint has neglible influence on thermal performance
Designing for TC Polycarbonate
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Painting & Decorating
Successfully tested
processes:
• Powder coating
• Solvent borne
• Water borne
• UV cure
Processing for TC Polycarbonate
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Ejection
Stripper Plate
2° Draft
Ample ejectors (sleeve, blade or
stripper plates) on fins/ribs
Locate tall or deep features on the
ejector side of the tool
Draw polish in the direction of part
ejection
Easy release coatings on the steel
to facilitate part release
Processing for TC Polycarbonate
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Mold Cooling
Excessive mold temperature
can cause sticking
Position cooling lines to provide
uniform mold temperatures
Highly conductive mold materials (ie
beryllium) are suggested (rib area)
Conductive inserts must provide a
thermal path to cooling lines
Processing for TC Polycarbonate
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Gate and Runner Systems
Tunnel-Gate Configuration
Three Plate
Mold
Three plate molds, edge gates, sub-gates and
direct drop hot manifolds are all acceptable
Sprue tip orifice diameters should be 0.8-1.0
times the wall thickness
Sub-gates should be 3 mm minimum
diameter, avoid cashew gates
Edge gates should be a ratio of 0.8-1.0
times the wall thickness
Manifold and runner systems should follow standard
design practice for polycarbonate materials
covestro.com
Thank You Jim Lorenzo, Terry Davis Covestro LLC
Makrolon is a registered trademark of the Covestro group
29
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