Fujikura ThermalTechnology Overview
Randeep Singh
Thermal Technology Division(ＴＴ開)
Fujikura Ltd. Tokyo1

Key Technology of Thermal ProductHeat Pipe

Vapor Chamber

Micro-channel

Merits:Passive system
Two phase heattransfer
One directional
heat flow

Merits:Passive system
Two phase heattransfer
Two directional
heat flow

Merits:Active system
Single phase heattransfer
Multi directional
heat flow2

Applications Areas
Cooling Electronics

Heat Pipes

EnergyHeat Pipe Module

Automotive
Application
Vapor Chamber

Aviation

Heat Sinks

Global Warming& Environment

Healthcare

3

Heat Pipe

4

Heat Pipe Operation Principle
Surface tension

𝟐𝝈𝒄𝒐𝒔φ = 𝝆𝒈𝒉Capillary=pressure𝒓

Contactangle

Operating Principle
1 Evaporation
2 Heat transfer by vapourr

𝝈3Single poreCondensation

4 Capillary or gravity pumping
Evaporator

1Wick

Liquid FlowHeat Source

Container
Condenser

VapourFlow

Sinteredcopper wick
Coppertube

Pore radiusφφ

Pumping height

3 Liquid
4
Heat Sink

Superior Heat Transfer Element!
Heat Pipes!
Container
Wick

Heat In

Heat Out
Heat Pipes

4) Liquid flow
1) Evaporation

3) Condensation
2) Vapor flow

Evaporator

Adiabatic Section

Composite Wick

CondenserSintered Wick

Heat Pipes have been
become popular andconsumer products now.
Approx. 13 Mil. Pcs / amonth heat pipes areproduced in the world.
Axially Grooved

6

Functions of thermal control device in cooling
Air InTeTa

Heatsource, TsTs

R s-cp

Air out

Heat Transfer

Heat Spreading

TsTc

Heatspreader

Heat Dissipation

TeR cp-hx

Tc

RtTa

R hx-aTa

Thermal circuit diagram

7

Summary of Cooling Design Trend for Desktop PCs
PGA

TYPE 2High aspect
extrusionparallel fins withcopper
embedded base

TYPE 3High aspect
extrusion radialfins with copper
insertion core

TYPE 4Fine pitch
stacked finssoldered heat
sink

TYPE 5Heat pipe heatsink

TYPE1Extrusion
parallel fins

Rca: 0.5 ℃/W
Low Performance

LGA

Rca: 0.2 ℃/WHigh Performance
8

Various Heat Pipe Remote Heat-Exchanger for Laptop PC

9Current Thermal Solution Trend for Thin Laptop-PC

Thin and Light Solution combination of 2mm thick or thinner heat pipewith Aluminum fins are applied in current Laptop PC.
10

Typical Consumer Products of Heat Pipes for Cooling PC

4 mm Heat Pipe

6 mm Heat Pipe

1 inch Heat Pipe

Vapor Chamber
11

High Power Heat Pipe Heat Sink for Desktop PC
System Fan

DC/DCHeat Sink

CPU HeatSinks

CPU Fan(Front)

130W/CPU x 2 CPUs

CPU Fan(Back)

12

TV LED BACK LIGHTS THERMAL MANAGEMENTHeat Pipe

TV LED Back Lights

Heat Pipe Cooling Module Sample

13Thinner Heat Pipes

1.5 mm thick : Qmax:25 W
Rhp: 0.2-0.3 K/W

1.0 mm thick : Qmax: 10 W
Rhp: 0.3-0.5 K/W

1

Thin Heat Pipe
Vapor Area

Wick Area
Fine Fiber
Vapor Gap(in center)
Regardless with the totalWick
innercross-sectionof the heat pipe, optimized liquid to vapor
flow area ratio is with the range of 0.5~0.6

Wick In Center

Vapor Gap

Porosity, ε : 0.7 ( Experimental Value)
0.6 for similar shape powder wickContact Angle, θ : 18 deg ( Experimental Value)

Permeability, K : 8.0x10-10 (Calculated Value]
7.5x10-11 for similar shapepowder wick15

Wick Structure of Thin & Flat Heat Pipe

Cross-Section of Center Fiber
Wick For 0.8mm to 2mm Thick
Heat Pipe

SpiralCu Wire

Spiraled TypeTwisted Type

Center Fiber Wick
WickFeatures :• Sufficient Capillary Force• Sufficient Vapor Space• Liquid Flow ThroughFiber and Groove under FiberVapor Space

X-Ray Picture of Straight Thin Heat Pipe

16Thin Heat Pipe Performance

6.00
Qmax . Leff [W.m]

5.00
4.00
3.00
2.00
Operating Temp : 60 [C]

1.00
0.00
0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

Flattened Thickness [mm]For a 2.0mm flattened thickness with the effective length 110mm
Qmax can be go up to 48W.
1717

Ultra-Thin Heat Pipe Performance1) D1.0mm Heat Pipe Thermal Performance

50C hot water

Heat Pipe Specification

Thermal Tape
Become Red at 45C

Length = 75mm

Wick : Center Fiber Wick

Vapor Flow Area

Wick
Liquid Flow Area
18

EXPERIMENTAL STUDY : Fabricated Module # 1
Specification

HeaterHeat Pipe : L 300.0mm T 1.3mm
Module Weight : 27gm and20gm
Maximum Height : 5.0mm
Heat Source : In Center

Fin
Assembly

Heat Pipe

Fin
Assembly

12.0mm
1.3mm
D8.0mm

9.0mm
1.3mm
D6.0mmUsing D8.0mm Qmax : 68W
Using D6.0mm Qmax : 64W

19

EXPERIMENTAL STUDY : Fabricated Module # 21.0mm
Heat Pipe

Specification
Heat Pipe : L 140.0mm W 9.0mm T 1.0mm
Module Weight : 19gm (Including Fan)
Maximum Height : 4.0mm

Heat Pipe Only

Fin Assy

DC Fan40x40x3mm

Cu Plate

Heat Pipe Module
Th is high,Not enough flow rate

Qmax 18W

Steady Resistance

Current module Qmax About 20W if Air Flow Available20

EXPERIMENTAL STUDY : Fabricated Module # 3TeTh

Specification
Heat Pipe : L 100.0mm W 9.4mm T 0.8mm
Module Weight : 14gm (Including Fan)
Maximum Height : 3.8mm
Total ResistanceTc

Ta

Temperature Profile

Horizontal Qmax 5W
Top Qmax 5W

Heater Temp Below 60C
At All Heat Mode
Bottom Qmax 7WCurrent module Qmax is 5~7W
21

EXPERIMENTAL STUDY : Fabricated Module # 40.8mm
Heat Pipe

Specification
Heat Pipe : L 140.0mm T 0.8mm
Module Weight : 12gm
Maximum Height : 3.8mm
Fin Assy : W 40mm L 10mm H 3.0mm

PYROID
T0.8mmWith Ni Plating

Pyroid Plate

Cu Plate
Fin Assy

Cu Plate

Estimated highest Qmax is 12.0W.

22

EXPERIMENTAL STUDY : Fabricated Module # 5100mm

Specification
Heat Pipe : L 100.0mm W 4.5mm T 0.6mm
Module Weight : 8gm
Heat Source : Three Heat Sources
H1 : 3W ; H2 : 1.5W H3: 1.5W
Maximum Height : 0.7mm

50mm

Th2HeatSource

Th1Th30.6mm
Heat Pipe0.1mm
Al SheetComparison
Current Module vs 0.7mm Thick Graphite Sheet

0.7mm Graphite

Current Module

For current module Th is 5~10C lower than graphite sheet.
23

Concept – Heat pipe + Spreader plate
Heat pipes and spreader plate

Back Panel• Heat pipes 0.7- 1mm thick.
• Metal (Al or Cu) spreader plate 0.2mm thick.
• Heat pipe is a super heat conducting
device, better than any known metal
due to its 2-phase internal heattransfer . Therefore, heat pipe is used
to spread the heat more efficient on
the heat spreader plate for bettercooling.

BatteryBoard

Thin Heat Pipe(Thickness 0.7mm)

Heat Spreader Plate（Al, Copper, SUS)24

Heat Pipe Applications for Vehicles

Head LampCooling

Display LED Back-Light Cooling,
Car Navigation CPU Cooling

Preheated Intake Air (FuelSystem, EnergyConservation)

Power Drive unit(PDU) Cooling

Rear Lamp Cooling

Battery Cooling(Hybrid)25