[1]

IMPROVING SYSTEM RELIABILITY WITH SYNJET COOLING

Central Texas Electronics Association Electronics

Design & Manufacturing Symposium

February 22, 2011

Markus Schwickert

[2]

SynJet® (Synthetic Jet) Operating Principle

• Rapid-fire pulses of turbulent air produced by an

oscillating diaphragm, typically 30 to 200

pulses/second

• Each pulse is well defined high momentum air

• High velocity air sheds vortices breaks up boundary

layers

Oscillating Diaphragm

Entrained Air

Synthetic Jet

Vortices Cavity

Nozzle

Entrained Air

• Pulsating flow increases mixing, that turbulence

increases heat transfer

• SynJet flow is synthesized entirely from the

ambient air

• A secondary flow is entrained from the

surrounding air due to the primary high

momentum jet

Heatsink

Flash Video Link: http://nuventix.com/synjet_flash_demo/

[3]

SynJet® Coolers

SynJet® Coolers are paired with different heatsinks

to provide full thermal solutions.

ZFlow 50 ZFlow 65 ZFlow 75 ZFlow 100 XFlow 30

[4]

SynJet® Cooler and Heatsink Solutions

ZFlow 50

MR16

Style

Downlights

Downlights

Removable

Designs

Spotlights

Linear lights

Par Style

500 1000 1500 2000 2500 3000

Approximate Lumens Cooled

ZFlow 65

Spotlight

21W

ZFlow 75

Spotlight

31W

ZFlow 75

Spotlight

34W

ZFlow 75

Spotlight

38W

ZFlow 65

Par20ZFlow 65

Par25ZFlow 65

Par30

XFlow 30

ZFlow 65

CoolTwist

ZFlow 100

Downlight

120

ZFlow

100

Downligh

t 140

[5]

SynJet XFlow 30 Cooler 40W

LED Module Lumens

(Approx.)~2500

Max Thermal Wattage

Cooled (Approx.)40W

Solution Length 110 mm

Solution Width 50 mm

Solution Height 30 mm

SynJet® Linear Cooler Solutions

[6]

SynJet® Target Markets

Solid State Lighting (LED)

• Increases light output by 2x

• Reduces heat sink volume by 3x

• Reliable, silent, flexible

Industrial Drives & Controls

• Allows higher performance implementation without sacrificing reliability

• Immune to harsh environments, dust, dirt, oils, etc

Telecom & Servers

• Reduces power consumption

• Reduces acoustic emissions

• Allows higher performance implementation without sacrificing reliability

SynJet cooling enables higher performance,

higher reliability, and quieter operation

[7]

SynJet® Thermal Solution

SynJet FlexCool Engine

SynJet Thermal Solution

SynJet ZFlow 75 with 31W Heatsink

Heatsink

SynJet Housing

SynJet Engines are used in multiple coolers. The outer housing

changes to meet the needs of the applications but the core air

generator is a standard assembly.

[8]

[9]

Rural Lighting

SynJet Case Studies

[10]

Lifetime Definition: L10

The point of time at which the cumulative failures of a product reach 10%

and 90% remain functioning as intended under stated conditions.

[11]

Failure Definition

Derived from the intended functions of a product, which include low acoustic emissions, high cooling performance and low power consumption of the SynJet product family.

Thus failures are defined by the following.

Loss of cooling performance over 10%

Noticeably increased acoustic emissions, such as over 10% or 3dB

Power consumption increase (product specific, typically 20%)

[12]

1000

10000

100000

1000000

10000000

20 30 40 50 60 70 80

Lif

e, H

ou

rs (L

10

)

Temperature, C

L10 Comparison Chart

Sleeve Bearing - low cost Single Ball Bearing - moderate cost Double Ball Bearing - higher cost SynJet™ - moderate cost

SynJet® and Fan Lifetime Comparison

At 60°C SynJet lifetime is

more than double a fan

[13]

48 hours of Dust Exposure

Fan stopped working after

40 hours SynJet remains in service

SynJet operation remained unaffected.

Thermal resistance before test: 0.91 °C/W

Thermal resistance with dust on heat sink: 0.99 °C/W

[14]

Dust Settlement

Fan blades experience too

high friction from Dust.

Dust will enter bearings

SynJet keeps working

[15]

Heat Sink Fins

Especially fibers foul heat

sink fins in fan setup

Periodic air action scrubbs

fins

[16]

Dust Testing

T ambient

Delta T Theta Delta T Theta

[C] [C/W] [C] [C/W]

CPU 25.79 1.03 25.15 1.01

Chipset 22.93 2.08 21.92 2.07

AfterBefore

24.87 C 22.82 C

Nuventix uses custom dust chamber for

quick design verifications.

Certified test facilities are used for IEC

/ANSI tests.

[17]

Dedicated in-house Reliability Facilities

Two walk-in temperature chambers with 100 square feet each, operating up to 95 °C

A one-thousand-piece active actuator test system designed for testing up to 125 °C.

Thermal cycling chamber

Humidity chamber

Altitude chamber

HAST temperature and humidity chamber

UV weathering chamber

Drop and shock tester

Dust exposure chamber

Two walk-in temperature chambers with 100

square feet each, operating up to 95 °C

A one-thousand-piece active actuator test system

designed for testing up to 125 °C

Thermal cycling chamber

Humidity chamber

Altitude chamber

HAST temperature and humidity chamber

UV weathering chamber

Drop and shock tester

Dust exposure chamber

[18]

Temperature and Humidity

Examples of SynJet test conditions are:

Operational at 70 °C / 90 % r.h. for 32 days [pass]

Non-operational and operational at 85 °C / 85 % r.h. for 3,300 hours [pass]

Espec LHU-113 Espec ETH-33

[19]

2 Walk-in Chambers, temperature controlled

[20] Nuventix Confidential

Shock and Vibration

Vibration Sine Sweep .15G @ 10Hz to

5G@60Hz, 5G 60-150Hz at 1 min/octave,

20 sweeps (1:18:08 per axis).

Vibration Sine Sweep .15G @ 10Hz to

5G@60Hz, 5G 60-600Hz at 1 min/octave, 1

sweeps (5:58 per axis).

Vibration Random 0.03g^2/Hz 5-500Hz, 20

minutes an axis. 3.85 Grms

Shock Pulses Half Sine 45G 11ms 6 shocks

in 6 directions, total 36 shocks

27 devices were tested in all three orientations

each. No failures.

Professional Testing

Lab, Round Rock,

TX

profile(t)

R1 Response:

Peak = 44.519 gn

C1 Control:

Peak = 44.960 gn

27-15 -12 -8 -4 0 4 8 12 16 20 24

100

-100

-90

-75

-60

-45

-30

-15

0

15

30

45

60

75

90

Time (Milliseconds)

gn

[21]

Highly Accelerated Life Testing

Combination Step Stress Method to find failure modes and weakest links.

Uses vibration and thermal stress.

[22]

Sample Reliability Tests and Results

Dust

48 hours of IEC dust testing showed no impact on performance

Low Temperature

-40 ˚C operational, 87 units, 3,200 hours, no failures [416, 417, 418]

-40 ˚C, storage, 11 units, 3,200 hours, no failures [432]

Thermal Cycling

-40 ˚C - +105 ˚C, thermal cycling, 200 cycles, 60 units, no failures [375 – 380]

Humidity testing:

85 ˚C / 85% r.h., operational, 20 samples, 3,250 hours, no failures [395, 396]

Cyclic condensing humidity test, 22 samples, 200 cycles between +50 ˚C / >95% r.h. and +5 ˚C / 5% r.h., such that condensation occurred,

no failures. [429, 430]

Powert Cycling

112 chip coolers were cycled for 15,000 power cycles at room temperature, followed by 15,000 cycles at 85 °C (15 sec on/off), no failures

[23]

Sample Reliability Tests and Results, continued

Lifetime

540 samples at 105 °C (brief periods of 95 °C) ambient operating for 3,300

hours, no failures (establishes a minimum of 100k hours of L10 at 85 °C with

>90% confidence) [393, 394, 409, 410]. Note: 75 units continued testing in operation at 85 C ,

no planned end date (ca. 2000 hours as of now).

Cyclic Ice/Freeze Test:

21 samples, 100 cycles between +25 ˚C / 95% r.h. and –10 ˚C / u.c.r.h. such

that units freeze in humidity and powering units on after 20 minutes of

freezing, no failures. [437]

Shock and vibration testing: [387 – 392]

Bump Test: 1,000 shocks, half sine wave, 25 G, 10 ms, each of 6 directions

5 to 150 Hz sine sweeping, 2 G, 5 sweeps each of 3 axes

20 minute dwell, 5G at max resonance, each of 3 axes

Random vibration, 2.2 grms, 20 minutes each of 3 axes

No failures.

HAST, 123 C, 96% r.h., 2 atm.

3 FlexCool40 units tested for 60 hours (non-operational), pass

[24]

Field Reliability Data

8,000 SynJets operating in one case since 8/25/2010

4,355 calendar hours under use conditions

Lifetime prediction L10 > 255k hours and counting

[25]

Reliability Block Diagram

Hot Component Other

b c

= a + b + c

One can further split the diagram into the parts of the components etc.

Cooling Solution

a

System Failure Rate:

[26]

Reliability Block Diagram, redundant components

Cooling Solution

Hot component Other

b c

= 1/(1/ a + 1/ a)+ b + c

= ½ a + b + c

Adding a component to the system usually lowers system reliability,

Cooling Solution

a

a

[27]

Effect of Adding Cooling Components to a System

Hot Component Other

b c

= a + b + c

Cooling Solution

a

System life time is always

Limited by the shortest life

time of any critical

component

[28]

Typical LED Light System Reliability Block Diagram

(50 °C ambient, simplified)

SynJet Cooling

SynJet

= 11.5

ppm

LED

component

at 80 °C

= 34.4

ppm

System = 45.9 ppm

LED

component

at 125 °C

= 164

ppm

Natural Convection

System = 163.5 ppm

L10 = 14,000 hr

Fan Cooling

Fan

= 66 ppm

LED

component

at 80 °C

= 34.4

ppm

System = 100.2 ppm

L10 = 23,000 hr

L10 = 50,000 hr