Central Texas Electronics Association Electronics Design & Manufacturing Symposium February 22, 2011 IMPROVING SYSTEM RELIABILITY WITH SYNJET COOLING

Transcription

1 Central Texas Electronics Association Electronics Design & Manufacturing Symposium February 22, 2011 IMPROVING SYSTEM RELIABILITY WITH SYNJET COOLING Markus Schwickert [1]

2 SynJet (Synthetic Jet) Operating Principle Synthetic Jet Entrained Air Oscillating Diaphragm Nozzle Heatsink Vortices Entrained Air Cavity 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 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 [2] Flash Video Link:

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 [3]

4 SynJet Cooler and Heatsink Solutions Approximate Lumens Cooled Downlights ZFlow 100 Downlight 120 ZFlow 100 Downligh t 140 Downlights Removable Designs ZFlow 65 CoolTwist Spotlights ZFlow 50 MR16 Style ZFlow 65 Spotlight 21W ZFlow 75 Spotlight 31W ZFlow 75 Spotlight 34W ZFlow 75 Spotlight 38W Par Style ZFlow 65 Par20 ZFlow 65 Par25 ZFlow 65 Par30 Linear lights XFlow 30 [4]

5 SynJet Linear Cooler Solutions SynJet XFlow 30 Cooler 40W LED Module Lumens (Approx.) Max Thermal Wattage Cooled (Approx.) ~ W Solution Length 110 mm Solution Width 50 mm Solution Height 30 mm [5]

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 [6]

7 SynJet Thermal Solution SynJet Thermal Solution SynJet ZFlow 75 with 31W Heatsink SynJet Housing SynJet FlexCool Engine Heatsink 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. [7]

8 [8]

9 SynJet Case Studies Rural Lighting [9]

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. [10]

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%) [11]

12 Life, Hours (L10) SynJet and Fan Lifetime Comparison L10 Comparison Chart Sleeve Bearing - low cost Single Ball Bearing - moderate cost Double Ball Bearing - higher cost SynJet - moderate cost At 60 C SynJet lifetime is more than double a fan [12] Temperature, C

13 48 hours of Dust Exposure Fan stopped working after 40 hours SynJet remains in service SynJet operation remained unaffected. Thermal resistance before test: Thermal resistance with dust on heat sink: 0.91 C/W 0.99 C/W [13]

14 Dust Settlement Fan blades experience too high friction from Dust. Dust will enter bearings SynJet keeps working [14]

15 Heat Sink Fins Especially fibers foul heat sink fins in fan setup Periodic air action scrubbs fins [15]

16 Dust Testing Nuventix uses custom dust chamber for quick design verifications. Certified test facilities are used for IEC /ANSI tests. Before After T ambient C C Delta T Theta Delta T Theta [C] [C/W] [C] [C/W] CPU Chipset [16]

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 HAST temperature temperature and and humidity humidity chamber chamber UV weathering chamber UV weathering chamber Drop and shock tester Drop and shock tester Dust exposure chamber Dust exposure chamber [17]

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 [18]

19 [19] 2 Walk-in Chambers, temperature controlled

20 Shock and Vibration Vibration Sine 10Hz to 5G@60Hz, 5G Hz at 1 min/octave, 20 sweeps (1:18:08 per axis). Vibration Sine 10Hz to 5G@60Hz, 5G Hz at 1 min/octave, 1 sweeps (5:58 per axis). Vibration Random 0.03g^2/Hz 5-500Hz, 20 minutes an axis 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. gn [20] Nuventix Confidential Professional Testing Lab, Round Rock, TX

21 Highly Accelerated Life Testing Combination Step Stress Method to find failure modes and weakest links. Uses vibration and thermal stress. [21]

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 C, thermal cycling, 200 cycles, 60 units, no failures [ ] 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 [22]

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 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: [ ] 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 [23]

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 [24]

25 Reliability Block Diagram System Failure Rate: = a + b + c a b c Cooling Solution Hot Component Other One can further split the diagram into the parts of the components etc. [25]

26 Reliability Block Diagram, redundant components a Cooling Solution a b Hot component c Other Cooling Solution = 1/(1/ a + 1/ a )+ b + c = ½ a + b + c Adding a component to the system usually lowers system reliability, [26]

27 Effect of Adding Cooling Components to a System = a + b + c System life time is always Limited by the shortest life time of any critical component Cooling Solution Hot Component Other [27] a b c

28 Typical LED Light System Reliability Block Diagram Natural Convection LED component at 125 C = 164 ppm (50 C ambient, simplified) System = ppm L10 = 14,000 hr Fan Cooling Fan = 66 ppm LED component at 80 C = 34.4 ppm System = ppm L10 = 23,000 hr [28] SynJet Cooling SynJet = 11.5 ppm LED component at 80 C = 34.4 ppm System = 45.9 ppm L10 = 50,000 hr