Webinar: Thermal Management 2013 - WE Home · 04/06/2013 Webinar: Thermal Management 2013 Würth Elektronik Circuit Board Technology Page 1

04/06/2013 www.we-online.com/thermal_management

Webinar: Thermal Management 2013Würth Elektronik Circuit Board Technology

Page 1

Agenda

Basic Thermal Management

Possibilities of heat dissipation

Applications

www.we-online.com/thermal_management04/06/2013 Page 2

Basic Thermal Management

Possibilities for heat dissipation

Applications

www.we-online.com/thermal_management04/06/2013

Agenda

Page 3

Over 50 % of electronic system failuresare caused by increased temperatures

Heat dissipation influences the systemefficiency

Sufficient cooling is essential for animproved reliability and lifetime.


Source::US Air Force Avionics Integrity Program (AVIP)

Dust

6% Vibrations

20%

Temperature

55%

Humidity

19%

Thermal Management - Basics

PCBs play an important role in the development of efficientthermal management

Page 4

Cooling strategies depend on different requirements of electronicsystems

Amount of thermal output

Available space / size of elements

Assembly technologies for components used

Complexity of circuit

Cooling concepts have to meet specific demands

Guarantee sufficient reliability

Provide for cost-benefit ratio



Page 5

In order to solve thermal problems analyse the whole system(component, circuit board, assembly, housing and environment)

Heat cannot be „destroyed“ the only possibility is to dissipate it fromthe hot component

Heat passes along the thermal path of different materials / substancesand interfaces they each represent a thermal resistance

The individual thermal resistances can be considered analogous to anelectrical series connection



Seite 6

System aspekts of thermal design


Rth (component)

Rth (com-pcb interconnection technology)

Rth (pcb)

Rth (contact area pcb-heatsink)

Rth (heatsink)

Rth (heat transfer to housing/environment)

warm

cold

Series connection of thermalresistances

Consideration of the entireheat path

Highest thermal resistance atinsulating layers, adhesivelayers, air inclusions, etc.

Maximise benefit by optimizingthe highest thermal resistor


Seite 7

GOAL: Reduction of thermal resistance

Layer thickness d reduced by

– thinner circuit board

– thinner insulation layers

Thermal conductivity λ increased by

– higher copper content

– parallel thermal vias in the z - axis

Cross section of thermal path A increased by– min. 25µm copper in the barrel ! parallel thermal vias

– large copper area for heat expansion (x/y)

– large contact surface area of copper / heat sink


thermal resistance Rth =length of thermal path d

thermal conductivity λ*cross section of thermal path A


Seite 8


Radiation: Emission of photons

Convection: Heat transfer through gases orfluids

Conduction: heat dissipation via solid objects

vertical: Thermal Via/Microvia/Buried Via

horizontal: copper foil heat spreading/heatsink

Types of heat dissipation


Seite 9

Time for a poll

www.we-online.com/thermal_managementSeite 1004/06/2013

Through which measures can the thermalresistance be reduced?

Basics Thermal Management


Applications


Agenda

Seite 11

Metal carrier with insulating layer and copper layer

Available as a complete base material

Simple circuits, usually only 1 35 microns copper layer in etching, solderresist

Disadvantage: - >1 copper layer is complex and expensive to produce quickly

- cut outs in aluminum or insulating layer are very expensive

Alternatives: thin DS board, Multilayer on aluminum



IMS = Insulated Metal Substrate

Source: Bergquist

Aluminum or Copper

Seite 12

Plated through holes used as "ThermalVias“

Mechanically drilled vias

Good heat conduction in z-axis throughthe copper barrel (wall thickness min.25 microns)

If the printed circuit board thickness ismore than 0.7 mm, it is recommended tofill the vias and metallized over withcopper



Thermal Vias

Seite 13


Filled Thermal Vias

End dimension Via: 0.3 mm ; Copper in the hole: 25 µm

Pitch Anzahl Vias LP Dicke 1,6mm / Rth in K/W LP Dicke 0,36mm / Rth in K/W λ in W/mK Cu - Anteil

1,9 mm 20 6,65 1,51 2,39 0,51%1,5 mm 50 3,12 0,71 5,13 1,28%1,2 mm 81 2,01 0,45 7,98 2,07%1,1 mm 100 1,64 0,37 9,74 2,55%1,0 mm 121 1,37 0,31 11,71 3,09%0,8 mm 176 0,95 0,21 16,89 4,49%0,6 mm 289 0,58 0,13 27,84 7,38%


Pad 10 x 10 mm

Seite 14


Thermal Vias Filling Prozess

Copper

FR4

Copper

Drilling

Metallized hole

Vacuum fillingprocess

Curing

Brushing/Grinding

Metallized


Seite 15


Ultra thin multilayer using blind Microviascombined with Buried Vias

Short heat path Microvias drilled directly intosolder pads no soldering problems

Complete decoupling of CTE mismatch

Combination Microvia/Buried Via


Seite 16


Double sided PCB ormultilayer with individual baredie bonded and assembled

Individual heatsinks glued

Miniaturization throughreduction of the installationheight

Bare Die

Heatsink


Seite 17


Heatsink

Bare Die


Double sided PCB ormultilayer with individual baredie bonded and assembled

Individual heatsinks glued

Miniaturization throughreduction of the installationheight

Optimizing heat management

Adjusting the beam angle

Seite 18

Time for a poll

www.we-online.com/thermal_managementSeite 1904/06/2013

Why is filling and covering of Thermal Viasrecommended?

Basics Thermal Management


Applications


Agenda

Seite 20


Heatsink circuit boards used in aircraft “hybrid” lighting

Applications

Optimal thermal management for very bright LEDs with highheat dissipation

Complex outline in a multi-panel

blister-free bonding between heat sink and pcb

weight saving with a 1.0 mm thin aluminum heatsink element

Seite 21


Modular power LED light bar

Applications

Extremely high luminance, lamp control is alreadyintegrated onto the PCB

Heat spreading already in two additional inner layers

Good solderability through filled and cappedThermal Vias

Source: WE

Seite 22


Maxon Motor compact drive

Thermal Vias

Threads onheatsink

Applications

Source: maxon motor ; WE

Compact drive with integrated controller, sensorand motor in an aluminum case

Robust, space-saving solution with high powerdensity (max. power 60W)

Highly dynamic, maintenance-free drive

Seite 23


Assembly using threads

Temperature measurement during usage

TWmax- max. Operation temperatureTW- Winding temperatureTS- Stator temperatureTP- PCB temperaturTG- Case temperatur

Maxon Motor compact drive

Source: maxon motor ; WE

Applications

Seite 24


Gearbox controller

Source: WE

Applications

4-layer Microvia - PCB with Aluminum Heatsinkelement

Optimized thermal management throughMicrovias in combination with Buried Vias

Ambient temperature –40°C to 125°C due topower dissipation

In series production for many years

Seite 25


4-Layer Flexwith Chip directly bonded oncopper Heatsink 0.8 mmwith ENIG-surface

2 Chips in Cavity

AlSi-wire bonding

Source: UNI Heidelberg/CERN

Applications

Seite 26


Cross section through the whole build-up

LASERCAVITY® - Two steps with different electrical

layers and electrical potentials

Aluminum Heatsink

Source: WE

Applications

Microvias for thermalconductivity

Seite 27


LASERCAVITY® LEDs + thermal management

400µm~ 12000 LEDs / 1dm²

Source: WE

Applications

Seite 28

04/06/2013 www.we-online.com/thermal_managementSeite 29

Thank you for your attention!

Bert HeinzWÜRTH ELEKTRONIK GmbH & Co. KGProdukt ManagementWärmemanagementCircuit Board TechnologyT.: +49 7622 397 477M.:+49 160 97211825E. [email protected]. www.we-online.com

Documents

Webinar: Thermal Management 2013 - WE Home · 04/06/2013 Webinar: Thermal Management 2013 Würth Elektronik Circuit Board Technology Page 1