© 2004 - 2007
2010
– 2010
Preventing The Terrible Wearables: Designing Robust Wearable Electronics
Cheryl Tulkoff, ASQ...
© 2004 - 2007
2010
Sound Familiar?
© 2004 - 2007
2010
Wearable Electronics are hot, hot, hot!
© 2004 - 2007
2010
Sensing is a Major Component in that Growth!
http://www.statista.com/statistics/259640/global-revenu...
© 2004 - 2007
2010
Wearable Tech is Everywhere…..
© 2004 - 2007
2010
Wearing the Cure
o29.1 million people in the US with diabetes
o350,000 using wearable insulin pumps...
© 2004 - 2007
2010
o“Another month, another bad experience with regard to reliability of wearable tech – this time with ...
© 2004 - 2007
2010
oSweat
oDocumented in blogs that Apple iPOD Nano’s have shorted out due to sweat
oStrain relief
oW...
© 2004 - 2007
2010
Terrible Wearables: Hall of Shame
oContacts rubbing skin raw
oHeat & sweat
ohttp://www.n3rdabl3.co...
© 2004 - 2007
2010
Terrible Wearables: Hall of Shame
oFitbit Recalls Force Activity- Tracking Wristband Due to Risk of ...
© 2004 - 2007
2010
o“Sunscreen melted my Nook”
oA tiny warning on the can reads it can damage some fabrics materials or...
© 2004 - 2007
2010
oHabit-forming wearable that will shock you! Literally…..
oFailure waiting to happen???
Pavlok: Is ...
© 2004 - 2007
2010
On Understanding the Use Environment
© 2004 - 2007
2010
oReliability is the measure of a product’s ability to
o…perform the specified function
o…at the cus...
© 2004 - 2007
2010
oWikipedia: “…miniature electronic devices that are worn by the bearer under, with or on top of cloth...
© 2004 - 2007
2010
oWhat is ‘Next Generation’ Technology?
oMaterials or designs currently being used, but not widely ad...
© 2004 - 2007
2010
oWhy is knowing about ‘Next Generation’ Technologies important?
oThese are the technologies that you...
© 2004 - 2007
2010
oOne of the most common drivers for failure is inappropriate adoption of new technologies
oThe path ...
© 2004 - 2007
2010
oMarket studies and mobile phone markets can skew reality of market adoption
oAnnual sales of >100 m...
© 2004 - 2007
2010
oEmbedded components
oUltra-small components (i.e., 01005 capacitors)
oNew substrate materials
oPo...
© 2004 - 2007
2010
Ensuring Wearable Electronics Reliability
oDfR at Concept / Block-Diagram Stage
oSpecification crea...
© 2004 - 2007
2010
Bringing it All Together
oTwo key specifications important to capture at concept/contract stage that...
© 2004 - 2007
2010
Reliability Goals
oIdentify and document two metrics
oDesired lifetime
oProduct performance
oDesi...
© 2004 - 2007
2010
oWhat is the desired lifetime of wearable electronics?
oRough equivalents: Clothes, shoes, watches, ...
© 2004 - 2007
2010
Product Performance: Warranty Returns
oConsumer Electronics
o5-25%
oLow Volume, Non Hi-Reliability...
© 2004 - 2007
2010
Product Performance: Survivability
oSome companies set reliability goals based on survivability
oOf...
© 2004 - 2007
2010
oTemperature Cycling
oTmax, Tmin, dwell, ramp times
oSustained Temperature
oT and exposure time
o...
© 2004 - 2007
2010
oUsually, the first approach is to use standards
oHowever, existing standards do not work well with ...
© 2004 - 2007
2010
oMaximum temperatures likely not a significant concern
oTypically far below ratings
Field Environme...
© 2004 - 2007
2010
oVibration
oNot typically affiliated with human body, but outliers can occur (especially with tools,...
© 2004 - 200107
o Bending (Cyclic / Overstress)
o Often considered one of the biggest risks in regards to
wearables
o ...
© 2004 - 2007
2010
Corrosion: Handling / Sweat
oComposition of dissolved salts in water
oCan include other biological ...
© 2004 - 200107
Handling / Sweat (cont.)
0
20
40
60
80
100
120
140
160
Raw stock After Cleaning Handling (offic...
© 2004 - 2007
2010
oIssue of exposure to water & rain must be addressed for wearable electronics to survive
oSome cell ...
© 2004 - 2007
2010
oExposure to ultraviolet (UV) is typically not sufficient to induce degradation in electronic materia...
© 2004 - 2007
2010
oOf Cities listed, Phoenix has highest avg annual exposure. Note: Model is isolated to UV. Humidity i...
© 2004 - 2007
2010
oWasher / Dryer
oCleaning fluids
oMud / Dust / Water
Other Challenging Environments for Wearables
© 2004 - 2007
2010
Environment (Best Practice)
oUse standards when…
oCertain aspects of your environment are common
o...
© 2004 - 2007
2010
oWearable electronics are an exciting revolution in our engagement with ourselves and the world aroun...
© 2004 - 2007
2010
Presenter Biography
oCheryl has over 20 years of experience in electronics manufacturing focusing on...
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Preventing the Terrible Wearables: Designing Robust Wearable Electronics

Wearable electronics offer both significant opportunities and significant challenges to the design community. To ensure reliable and safe products, designers must be aware of new device packaging constraints, environmental conditions like sweat, UV & temperature exposure, tumble & drop, bending and torque, and the inevitable water immersion. Wearable electronics are an exciting revolution in our engagement with ourselves and the world around us However, there are clear risks -Wearables use new technology that hasn’t been fully characterized -They’ll be placed in environments not fully considered by the designers
Published on: Mar 4, 2016
Published in: Technology      
Source: www.slideshare.net


Transcripts - Preventing the Terrible Wearables: Designing Robust Wearable Electronics

  • 1. © 2004 - 2007 2010 – 2010 Preventing The Terrible Wearables: Designing Robust Wearable Electronics Cheryl Tulkoff, ASQ CRE Senior Member of the Technical Staff ctulkoff@dfrsolutions.com November 2014
  • 2. © 2004 - 2007 2010 Sound Familiar?
  • 3. © 2004 - 2007 2010 Wearable Electronics are hot, hot, hot!
  • 4. © 2004 - 2007 2010 Sensing is a Major Component in that Growth! http://www.statista.com/statistics/259640/global-revenue-from-mems-motion- sensors-in-wearable-fitness-devices/
  • 5. © 2004 - 2007 2010 Wearable Tech is Everywhere…..
  • 6. © 2004 - 2007 2010 Wearing the Cure o29.1 million people in the US with diabetes o350,000 using wearable insulin pumps oLux Research: clinical wearable devices should surpass their consumer counterparts in revenue by 2020 Beauty and Wearable Tech: Miss Idaho Proudly Displays Her Insulin Pump Medtronic's MiniMed Paradigm Revel Insulin pump senses blood sugar in real time
  • 7. © 2004 - 2007 2010 o“Another month, another bad experience with regard to reliability of wearable tech – this time with the Fitbit Flex. When the silicon wristband was only about a month old, it started coming apart…..” o“Did you try turning it off, and then on again? How about charging it?” o“After the first time you go through that dance, you realize it will never ever work. The failure mode is 100% catastrophic from the point of view of the user.” But “Reliability is Letting Wearable Tech Down” http://wearabletechwatch.net/2013/09/06/reliability-is-letting-wearable-tech- down/ http://forums.jawbone.com/t5/SUGGESTIONS/Is-the-UP24-Reliable-now/td- p/79393
  • 8. © 2004 - 2007 2010 oSweat oDocumented in blogs that Apple iPOD Nano’s have shorted out due to sweat oStrain relief oWearable on clothing, attached by a cord to power device, failed prematurely due to a lack of strain relief oPlasticizer oFirst-generation of Amazon Kindle wiring insulation cracked/crumbled due to the use of non-optimized plasticizer formulation oCyclic Fatigue oInitial video game controllers experienced fatigue of solder joints on components attached to the backside of the push buttons How Have Wearable Consumer Electronics Failed?
  • 9. © 2004 - 2007 2010 Terrible Wearables: Hall of Shame oContacts rubbing skin raw oHeat & sweat ohttp://www.n3rdabl3.co.uk/2014/07/lg-g-watch- charging-points-cause-injury-users/ http://wearabletechwatch.net o“In taking blood pressure readings, the Withings blood pressure monitor failed every time (but one), all at the same point”
  • 10. © 2004 - 2007 2010 Terrible Wearables: Hall of Shame oFitbit Recalls Force Activity- Tracking Wristband Due to Risk of Skin Irritation oComplaints of itchy, irritated wrists oAllergic contact dermatitis oEither the nickel that's in the stainless steel part of the device oOr adhesives or other materials used in the strap
  • 11. © 2004 - 2007 2010 o“Sunscreen melted my Nook” oA tiny warning on the can reads it can damage some fabrics materials or surfaces. ohttp://bcove.me/hh5yfn26 Terrible Wearables: Hall of Shame
  • 12. © 2004 - 2007 2010 oHabit-forming wearable that will shock you! Literally….. oFailure waiting to happen??? Pavlok: Is This a Wearable Device for You?
  • 13. © 2004 - 2007 2010 On Understanding the Use Environment
  • 14. © 2004 - 2007 2010 oReliability is the measure of a product’s ability to o…perform the specified function o…at the customer (with their use environment) o…over the desired lifetime oTo ensure reliability, we have to think about oWhat is the product supposed to do? oWhere is going to be used? oHow long should it last? What is Reliability?
  • 15. © 2004 - 2007 2010 oWikipedia: “…miniature electronic devices that are worn by the bearer under, with or on top of clothing.” oThat’s It?! oAlternative Definition oTechnology attached to the human body or clothing that allows the wearer to monitor, engage with, and control devices, themselves, or their social network What are Wearable Electronics?
  • 16. © 2004 - 2007 2010 oWhat is ‘Next Generation’ Technology? oMaterials or designs currently being used, but not widely adopted (especially among hi reliability manufacturers) oCarbon nanotubes are not ‘Next Generation’ oNot used in electronic applications oBall grid array (BGA) is not ‘Next Generation’ oWidely adopted Wearable Electronics Use Next Generation Technology Carbon Nanotube Array for Tissue Regen. & Wound Repair
  • 17. © 2004 - 2007 2010 oWhy is knowing about ‘Next Generation’ Technologies important? oThese are the technologies that you or your supply chain will use to improve your product oCheaper, Faster, Stronger, ‘Environmentally-Friendly’, etc. oHowever… Next Generation Technology (cont.)
  • 18. © 2004 - 2007 2010 oOne of the most common drivers for failure is inappropriate adoption of new technologies oThe path from consumer (high volume, short lifetime) to high reliability is not always clear oObtaining relevant information can be difficult oInformation is often segmented oFocus on opportunity, not risks oSources are either marketing mush or confusing, scientific studies oWhere is the practical advice? Reliability and Next Gen Technologies
  • 19. © 2004 - 2007 2010 oMarket studies and mobile phone markets can skew reality of market adoption oAnnual sales of >100 million may be due to one or two customers oMobile phone requirements may not match the needs of wearable electronics oMarket studies exclusively focused on volume oMore relevant may be number of customers oExample: 0201 capacitors Next Gen Technologies: The Reality
  • 20. © 2004 - 2007 2010 oEmbedded components oUltra-small components (i.e., 01005 capacitors) oNew substrate materials oPolyethersulfone, polyethylene terephthalate (PET), polyethylene napthalate (PEN) oPolyimide is not a next gen technology oPrinted connections oSilver inks, copper inks, nanosolders, conductive polymers oOrganic displays oPower Via Supercapacitors Examples of Next Gen Technologies in Wearables
  • 21. © 2004 - 2007 2010 Ensuring Wearable Electronics Reliability oDfR at Concept / Block-Diagram Stage oSpecification creation oPart Selection oDerating and uprating oDesign for Manufacturability oReliability is only as good as what you make oWearout Mechanisms and Physics of Failure oPredicting degradation in today’s electronics
  • 22. © 2004 - 2007 2010 Bringing it All Together oTwo key specifications important to capture at concept/contract stage that influence reliability Reliability expectations Use environment Appropriate Material Selection
  • 23. © 2004 - 2007 2010 Reliability Goals oIdentify and document two metrics oDesired lifetime oProduct performance oDesired lifetime oDefined as when the customer will be satisfied oShould be actively used in development of part and product qualification oProduct performance oReturns during the warranty period oSurvivability over lifetime at a set confidence level oMTBF or MTTF calculation should be primarily an administrative or marketing exercise (response to customer demands)
  • 24. © 2004 - 2007 2010 oWhat is the desired lifetime of wearable electronics? oRough equivalents: Clothes, shoes, watches, glasses, cell phones oClothes: ?? oShoes: 3 months to 5 years (600 miles) oWatches: 3 to 20 years oGlasses: 2 to 5 years oCell phones: 12 to 36 months oWith a new technology, there is an opportunity to influence expectations Desired Lifetime and Wearable Electronics
  • 25. © 2004 - 2007 2010 Product Performance: Warranty Returns oConsumer Electronics o5-25% oLow Volume, Non Hi-Reliability o1 to 2% oIndustrial Controls o500 to 2000 ppm (1st Year) oAutomotive o1 to 5% (Electrical, 1st Year) oCan also be reported as problems per 100 vehicles
  • 26. © 2004 - 2007 2010 Product Performance: Survivability oSome companies set reliability goals based on survivability oOften bounded by confidence levels oExample: 95% reliability with 90% confidence over 15 years oAdvantages oHelps set bounds on test time and sample size oDoes not assume a failure rate behavior (decreasing, increasing, steady-state)
  • 27. © 2004 - 2007 2010 oTemperature Cycling oTmax, Tmin, dwell, ramp times oSustained Temperature oT and exposure time oHumidity oControlled, condensation oCorrosion oSalt, corrosive gases (Cl2, etc.), UV oPower cycling oDuty cycles, power dissipation oElectrical Loads oVoltage, current, current density oStatic and transient oElectrical Noise oMechanical Bending (Static and Cyclic) oBoard-level strain oRandom Vibration oPSD, exposure time, kurtosis oHarmonic Vibration oG and frequency oMechanical shock oG, wave form, # of events Identify and Quantify Failure Inducing Loads
  • 28. © 2004 - 2007 2010 oUsually, the first approach is to use standards oHowever, existing standards do not work well with wearable electronics oMore geared towards permanent installations Identify Environment: Standards IPC SM785 MIL HDBK310
  • 29. © 2004 - 2007 2010 oMaximum temperatures likely not a significant concern oTypically far below ratings Field Environment: Body & Outdoor Temperatures oHowever, very cold temperatures (below -20C) could be a challenge oEspecially in combination with a mechanical load
  • 30. © 2004 - 2007 2010 oVibration oNot typically affiliated with human body, but outliers can occur (especially with tools, transportation) oExamples: Jackhammer, reciprocating saw oHave induced failures in rigid medical devices oMechanical Shock oDrop loads can reach 1500g for mobile phone (some OEMs evaluate up to 10,000g) oLikely to be lower for lighter wearables, but could be repeated (i.e., affiliated with shoes) Field Environment: Mechanical
  • 31. © 2004 - 200107 o Bending (Cyclic / Overstress) o Often considered one of the biggest risks in regards to wearables o Certain human movements that induce bending (flexing of the knee) can occur over 1,000/day o Case Study o There is indication that next-gen substrate materials experience a change in electrical properties after exposure to bending o Can be exacerbated by elevated temperature Field Environment: Mechanical (cont.)
  • 32. © 2004 - 2007 2010 Corrosion: Handling / Sweat oComposition of dissolved salts in water oCan include other biological molecules. oMain constituents, after the solvent (water), oChloride, sodium, potassium, calcium, magnesium, lactate, and urea. oChloride and sodium dominate. oTo a lesser but highly variable extent, iron, copper, urocanate (and the parent molecule histidine), and other metals, proteins, and enzymes are also present. oThe main concern regarding sweat is as a source of chloride
  • 33. © 2004 - 200107 Handling / Sweat (cont.) 0 20 40 60 80 100 120 140 160 Raw stock After Cleaning Handling (office) Handling (exercise) Handling (brow) Type of Exposure Contamination Extracted (μg) Chloride Sodium Potassium Calcium Magnesium Lactic acid 5 Handling (after wiping brow) 0.00 46.61 0.39 0.00 0.36 1.20 0.14 4 Handling (after exercise) 0.00 25.63 0.39 0.00 0.41 0.92 0.09 3 Handling (office environment) 0.00 14.35 0.49 0.00 0.41 1.30 0.10 2 After polish and clean 0.00 0.47 0.45 0.00 0.21 1.07 0.09 1 Raw stock aluminum 0.00 2.14 0.43 0.00 0.26 1.00 0.07 SO4 (μg/in2) PO4 (μg/in2) NO3 (μg/in2) Br (μg/in2) NO2 (μg/in2) Cl (μg/in2) F (μg/in2) ID
  • 34. © 2004 - 2007 2010 oIssue of exposure to water & rain must be addressed for wearable electronics to survive oSome cell phone manufacturers coat the product with either a conformal coating or a superhydrophobic coating to protect the electronics Rain & Water Immersion Challenges
  • 35. © 2004 - 2007 2010 oExposure to ultraviolet (UV) is typically not sufficient to induce degradation in electronic materials oHowever, a combination of temperature, moisture, and UV can break polymeric chains oExact combination, and specific portion of the UV spectrum, is not always well characterized oIt has been documented that stress corrosion cracking has been caused by sunscreen lotion Corrosion: UV Exposure
  • 36. © 2004 - 2007 2010 oOf Cities listed, Phoenix has highest avg annual exposure. Note: Model is isolated to UV. Humidity is not included. UV Exposure Annual UV Energy Calculations by City City Latitude Average Total Energy at 340nm (W*hr/m^2/nm) Average Annual Total Radiant Dose at 340nm (kJ/m^2/nm) Singapore 1 426 1532 Paris, France 48 499 1796 Sao Paulo, Brazil 22 553 1991 Tokyo, Japan 35 570 2053 Guatemala 14 648 2334 Miami, FL 25 661 2380 New York NY 40 661 2381 Barcelona, Spain 41 662 2382 Brasilia, Brazil 15 662 2383 Melbourne, Australia 37 708 2549 Buenos Aires, Argentina 34 727 2618 Baghdad, Iraq 33 732 2634 Minneapolis, MN 44 735 2647 Townsville, Australia 19 743 2673 Madrid, Spain 40 748 2694 LA, CA 34 767 2761 Phoenix, AZ 33 869 3129 http://www.drb-mattech.co.uk/uv%20map.html Annual UV Intensity – Global Picture
  • 37. © 2004 - 2007 2010 oWasher / Dryer oCleaning fluids oMud / Dust / Water Other Challenging Environments for Wearables
  • 38. © 2004 - 2007 2010 Environment (Best Practice) oUse standards when… oCertain aspects of your environment are common oNo access to use environment oMeasure when… oCertain aspects of your environment are unique oStrong relationship with customer oDo not mistake test specifications for the actual use environment oCommon mistake with mechanical loads
  • 39. © 2004 - 2007 2010 oWearable electronics are an exciting revolution in our engagement with ourselves and the world around us oHowever, there are clear risks oWearables use new technology that hasn’t been fully characterized oThey’ll be placed in environments not fully considered by the designers oResults if wearable manufacturers don’t use industry best practices &physics of failure to qualify their technology: oUnexpected failures oDelays in product launch oAdvisory notices (medical tech) Conclusions
  • 40. © 2004 - 2007 2010 Presenter Biography oCheryl has over 20 years of experience in electronics manufacturing focusing on failure analysis and reliability. She is passionate about applying her unique background to enable her clients to maximize and accelerate product design and development while saving time, managing resources, and improving customer satisfaction. oThroughout her career, Cheryl has had extensive training experience and is a published author and a senior member of both ASQ and IEEE. She views teaching as a two-way process that enables her to impart her knowledge on to others as well as reinforce her own understanding and ability to explain complex concepts through student interaction. A passionate advocate of continued learning, Cheryl has taught electronics workshops that introduced her to numerous fascinating companies, people, and cultures. oCheryl has served as chairman of the IEEE Central Texas Women in Engineering and IEEE Accelerated Stress Testing and Reliability sections and is an ASQ Certified Reliability Engineer, an SMTA Speaker of Distinction and serves on ASQ, IPC and iNEMI committees. oCheryl earned her Bachelor of Mechanical Engineering degree from Georgia Tech and is currently a student in the UT Austin Masters of Science in Technology Commercialization (MSTC) program. She was drawn to the MSTC program as an avenue that will allow her to acquire relevant and current business skills which, combined with her technical background, will serve as a springboard enabling her clients to succeed in introducing reliable, blockbuster products tailored to the best market segment. oIn her free time, Cheryl loves to run! She’s had the good fortune to run everything from 5k’s to 100 milers including the Boston Marathon, the Tahoe Triple (three marathons in 3 days) and the nonstop Rocky Raccoon 100 miler. She also enjoys travel and has visited 46 US states and over 20 countries around the world. Cheryl combines these two passions in what she calls “running tourism” which lets her quickly get her bearings and see the sights in new places.

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