Environmental Testing

Environmental Testing In C Charg harge e – TUV India P Ltd. Ltd. TUV Nord Group Germany

Environmental Testing What is & Why Environmental Testing?

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Reliability of Electronic product depends largely largely on the operating conditions conditions and environments that are encountered during the entire life of a product. It is therefore important that the product should perform satisfactorily under various environmental conditions and stresses Environmental Environ mental testing is intended to demonstrate with some degree of assurance that a product will w ill survive survive and perform under specified environmen environmental tal conditions Environmental Environ mental testing is a laboratory process wherein w herein an Electronic product is subjected to various environm e nvironmental ental conditions, and its performance checked against the design parameters and specifications

Environmental Testing What is & Why Environmental Testing? Evaluating an electronic product should not be limited to evaluating its performance and function but it is important to determine : 1. .

At what level can the performance be maintained and for how long? and its severity it encounters i.e. how is the Quality and Reliability of the product?  Quality defects occurring after a product is placed in the market not  only add to the cost but also affects reputation of the manufacturer  To avoid such damages ,Quality must be confirmed and ensured  before the Product is placed into the market  Environmental Testing not only confirms and ensures Quality and  Reliability but is also a indispensable prerequisite to  “ QUALITY ASSUARANCE” 

Environmental Testing Environmental Tests can be broadly classified into : •

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Climatic Environmental Tests: deal with temperature, humidity, pressure, etc deal with shock, vibration, etc Combined Environmental Tests: deal with a combination of the above two e.g. temperature + humidity + vibration

Environmental Testing

Environments and their effects High Temperature (Dry Heat) Principle Effects: Thermal Aging – oxidation, cracking, chemical reactions, softening, melting, sublimation, viscosity reduction, evaporation, expansion Imposes a particularly severe stress on most components and equipment since it can not only cause catastrophic failures such as melting of solders and burnout of solid state devices but also slow progressive deterioration of component performance levels due to chemical degradation effect. • • • • • • • • •

Variation/drift in R, L, C, Tan d, Dielectric constant values Overheating of wound components (e.g. Transformers) & electromechanical components Variation in Circuit Stability Softening /Swelling of Insulations Jamming of moving parts due to expansion Loss of viscosity of lubricants Alterations in the operating/release margins of relays, magnetically or thermally activated devices Change in Material dimensions Deterioration of surface finishes

Environments and their effects Low Temperature (Cold) Principle Effects: Embrittlement, Ice formation, Increased Viscosity & Solidification, Loss of Mechanical Strength ,Physical Contraction, Examples of some problems that could occur are: • Embrittles and lowers flexibility of rubbers and plastics (e.g. Seals of capacitors, panel gaskets, etc.) • ar a on r n , , , an , e ec r c cons an , va ues • Change in performance of wound and electromechanical components • Freezing of moisture : insulation failures • Variation in Circuit Stability • Increased wear of moving parts due to contraction or loss of mechanical strength, stiffening of shock/vibration mounts Increase in viscosity of lubricants • Condensation / freezing of water (cooling medium) • Deterioration of surface finish •

Environments and their effects Humidity (Damp Heat) Principle Effects: Moisture absorption or adsorption, Swelling, Loss of Mechanical strength, Chemical reactions (e.g. corrosion, electrolysis), Increased conductivity of insulations, Examples of some problems that could occur are: • Electrical Shorts, fogging of optical surfaces, changes in thermal transfer • • • • •

Swelling of seals and gaskets ( low humidity causes brittleness) Formation of surface films on metallic parts causing leakage paths and degradation of insulation and dielectric properties Failure of wound components Mechanical failures , cracking etc. Deterioration of surface finish (corrosion)

Environments and their effects Pressure (Altitude) Principle Effects: High Pressure: Compression, deformation Low Pressure: Expansion, Reduced electric strength of air,corona and ozone formation, reduced cooling Examples of some problems that could occur are: • Mechanical Failures ; seals , gaskets (rupture of capacitor seals) • Affects electronics used in aeronautics • Component parameter drift causing unreliable performance • Overheating due to reduced heat transfer • Evaporation of lubricants • Failure of hermetic seals

Environments and their effects Dust and Sand Principle Effects: Abrasion and erosion, Seizure, Clogging, reduced thermal conductivity, electrostatic effects Examples of some problems that could occur are: • Marring and abrasion of surface finishes increasing friction and temperature rise • on am na on o u r can s • Clogging of filters / pipes • Electrical failures due to conductive dust • Explosion/fire due to explosive dust • Overheating due to reduced heat sinking causing drift in electrical / electronic parameters Physical interference with mating parts ( mechanical alignment) • Interference with optical characteristics. •

Environments and their effects Corrosive Atmosphere (Salt Mist /Fog) Principle Effects: Chemical reactions (e.g. corrosion, electrolysis), surface deterioration, increased conductivity and contact resistance Examples of some problems that could occur are: • Increased wear • Mechanical failures due to corrosion of metal parts • Electrical failures: degrades insulation, produces conductive coatings ( failure of wound components, pcbs.) • Deterioration of surface finish: blistering of paint

Environments and their effects Vibration Principle Effects: Mechanical stress, fatigue, resonance Vibration results in dynamic deflections of and within materials causing structural fatigue ,mechanical wear of structures ,assemblies and parts and disruption of normal functions and performance. Examples of some problems that could occur are: • • • • • • • • • • • • •

Chafed wiring (leading to short circuits) Loose fasteners/components rea age o component ea s / mount ngs Intermittent electrical contacts Electrical shorts Deformed seals and mechanical parts Failed components Optical/mechanical misalignment Cracked &/or broken structures (PCBs) Particles & failed component lodged in circuitry or mechanisms Excessive electrical noise Excessive acoustic noise Deterioration of surface finish

Environments and their effects Shock (Mechanical) Principle Effects: Mechanical stress, fatigue, resonance Shock test is performed to provide a degree of confidence that the product can physically and functionally withstand the shocks encountered in handling, transportation and operating environment. Types of Shock tests: Bump, Drop/Topple, Impact Examples of some problems that could occur are: • • • • • • • • • •

a e w r ng ea ng o s or c rcu s Loose fasteners/components Breakage of component leads / mountings Intermittent electrical contacts Electrical shorts Deformed seals and mechanical parts Failed components Optical/mechanical misalignment Cracked &/or broken structures (PCBs) Particles & failed component lodged in circuitry or mechanisms

Environments and their effects

Environment Factors & Failures

Environmental Tests 1. 2. 3. 4. 5. . 7. 8. 9. 10. 11.

Dry Heat Cold Damp Heat (Humidity) Steady State & Cyclic Salt Spray Low Pressure (Altitude) Vibration Sine and Random Impact Shock and Bump Free fall ,Drop and Topple Mould growth Ingress Protection

Environmental Test Procedure A Environmental test will normally comprise of the following operations:

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Pre-conditioning Initial examination and measurements

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Conditioning Recovery Final examination and measurements

Environmental Test Procedure Data required to conduct a environmental test: • Preconditioning : (if applicable) severity and duration [@ambient / other temperature] • •

Initial Examination & Measurements: Visual ,parameters to be measured ,functional checks to be carried out Conditioning : Severity :- e.g. Temp. ,% humidity, vibration- frequency, amplitude etc. -

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Condition of test item:- with / without - electrical power/load Monitoring:- parameters to be monitored during the conditioning Recovery: in hours (if applicable) Final Examination & Measurements: Visual, parameters to be measured, functional checks to be carried out –  -during the test -at the end of the test while product is in the test chamber -or after recovery @ room ambient

Environmental Test Standards International • • • •

International Electrotechnical Commission (IEC) :IEC 60068 series European : EN 60068 series US Military: MIL-STD-810 ,MIL-STD-202,MIL-STD-750,MIL-STD-883 Japan : JIS C0010 series

Indian • Domestic : IS 9000 series (Bureau of India Standards) • Defence : JSS 55555 , JSS 50101 • Railway : RDSO •

Telecom : QM 333

Environmental Test Standards

Environmental Test Standards

Environmental Test Standards

Equipment for Environmental Tests Applicable standard: IEC 60068 For Climatic Tests: Environmental Test Chambers For Mechanical : Vibration test systems Impact test apparatus Bump test machine Ingress Protection : Dust Chamber Ingress test fingers Water spray/immersion test setup

Environmental Test Facilities in India

Environmental Test Facility should be Accreditted by NABL (comply with the ISO 17025 standard) •

Electronic Regional Test Labs/Electronic Test and Devp. Centres

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ERDA Vadodara ARAI Pune VRDE Ahmednagar (DRDO lab)

Thanks For further information contact: K M Deshmukh In Charge - Product Certification Auditor Ex / IEC Ex Certification TUV India P Ltd Pune [email protected]