HSP presentation

The application of printable heatsinks and interfaces as
solution of thermal problems on printed circuit boards
- Characteristics, application, rationalisation and cost saving potential -
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Heat transfer / thermal conductivity
Reasons for failure of electronic systems
Radiation
Free convection
Forced
convection
Heat
conductivity in
the PCB
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Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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HSP-Technology: Examples application
Assembly from the telecommmunication
field (transmission areals), heated-up
80°C above environmental temperature
Printed heatsink „front side“, approx.
500 µm thickness, heat-up only 33°C
above environmental temperature
© Lackwerke Peters GmbH + Co KG, Hooghe Weg 13, 47906 Kempen,
Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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Thermography: Experiment set-up
3
3
2
1
5
4
4
PCB rear
1 Voltage source
2 Resistor (70°C)
3 IR-camera
4 PCB
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Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
PCB front
5 Heatsink
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Thermography: Comparative measurements
PCB without heatsink
PCB with Cu-heatsink
PCB with HSP 2741
Heat-up phase
Measurement PCB surface after
1 min thermal load
Heating phase
Measurement PCB surface after
1 min thermal load
Cool down phase
Measurement PCB surface after 4 min
Heating and subsequent 4 min cooling down
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Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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Heat transfer / thermal conductivity
Classical heat transfer
Thermal interface or heatsink paste
printed
Heat transfer with a combination
of thermal interface paste and heatsink
„Thermal
coupling“
Material
Thermal conductivity 
[W/m K]
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Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
Copper
~ 400
Tin
~ 64
HSP 2741
~2
Polymers
~ 0,2 – 0,4
Air
~ 0,02 – 0,03
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Heat transfer / thermal conductivity
Thermodynamics
Electric Power
absolute thermal resistance Rth
electric resistance R
temperature difference ΔT
electric tension U
heat flow Q‘
electric power I
thermal conductivity λ
electric conductivity δ
thermal capacity Cth = cv . V
electric capacity C
© Lackwerke Peters GmbH + Co KG, Hooghe Weg 13, 47906 Kempen,
Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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PCB in HSP-technology
HSP-technology (HSP 2741)
1 Heat via
2 Solder mask
3 HSP 2741
4PCB core
„Classical“ technology
Solder mask
Cu-heatsink
adhesive
No heat transition resistance
Heat-via completely
plugged
No air inclusions
Function heatsink paste: improvement heat transfer and heat dissipation
© Lackwerke Peters GmbH + Co KG, Hooghe Weg 13, 47906 Kempen,
Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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Considerations interface metal – TIM
•
Metal
Thermal interface paste and heatsink paste
Fluid
Solid
Metal
has a connection to metal / fluid and to metal / solid
•
Metal
Thermal grease
Fluid
has two metal / fluid connections
•
Fluid
Metal
Metal
Thermal foil or pad
Solid
has two metal / solid connections
Rj = Heat transfer resistance
•
•
Metal Fluid: close to zero
Metal Solid : Rj subject to hardness, roughness and
contact pressure
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Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
Solid
Metal
• To be observed:
- Differences material CTE
- Stress versus efficient coupling
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HSP-technology: Examples application
Heatsink pastes HSP 2740 and HSP 2741
• Epoxy based
• Soldering resistant
• High (chemical) resistance
• Very hard
Typical processing by PCB-manufacturer:
• Preparation of screen or stencil
• 1. Print (e.g. plugging of heat vias)
• Intermediate cure if needed
• 2. Print (building up layer)
• Thermal cure (45 min @ 150°C)
Heatsink paste TIP 2792
• Silicone base
• Soft/elastic = better connection to cooling element
• Soldering resistant
Typical processing by PCB-manufacturer
• similar to HSP 2740 / HSP 2741, thermal cure 30 min
@ 120°C
© Lackwerke Peters GmbH + Co KG, Hooghe Weg 13, 47906 Kempen,
Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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HSP / TIP-technology: Examples application
© Lackwerke Peters GmbH + Co KG, Hooghe Weg 13, 47906 Kempen,
Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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Thermal grease / foil / pad
•
„Pumping effect“
•
Ageing
•
Uncontrolled layer
thicknesses
•
Additional process
at assembly level
•
Amount of scrap
•
Tools needed /
manual labor
•
Cost
•
Additional process
at assembly level
© computerbase.de
•
•
Thermal conductivity 3,8 W/mK
Reduction processer 10%
Gap Pad 2000S40
•
•
Thermal conductivity 2 W/mK
UL 94 V0
© Lackwerke Peters GmbH + Co KG, Hooghe Weg 13, 47906 Kempen,
Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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Thermal interface paste: Summary
•
Good thermal conductivity
•
Electrical insulator
•
Can be combined with HSP to
enhance coupling heat vias and carry
out double prints where required
•
Soft / elastic adjustment leading to
excellent thermal coupling
© Hardwareluxx.de
•
Low thickness = little heat resistance
•
Steady performance during operation
•
Application carried out by PCB
supplier, no additional processes at
assembly level
•
No scrap
© Bergquist
© Lackwerke Peters GmbH + Co KG, Hooghe Weg 13, 47906 Kempen,
Tel.: +49 (0) 2152-2009-0, Fax.: -70, [email protected], www.peters.de
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