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On Conductive Anodic Filament (CAF) Failures of Electronic Circuits Effect of Bias (up to 1000 V DC) on Conductive Anodic Filament (CAF) Failures of Electronic Circuits Ling Zou 16 July 2019 NPL Management Ltd - Commercial 1 Your Delegate Webinar Control Panel Open and close your panel Full screen view Submit text questions during or at the end 2 You can book your next webinar at https://www.npl.co.uk/electronic-and-magnetic-materials/electronics-reliability-webinars NPL Webinars – 2019 Electrical and Thermal Material Evaluation Using Power Cycling Testing For Power Electronic Applications 17th September Battery Metrology At NPL – Lithium Ion Cell Characterisation 12th November Book Your Place today http://www.npl.co.uk/science-technology/electronics-interconnection/webinars/ NPL Management Ltd - Commercial 3 Effect of Bias (up to 1000 V DC) on Conductive Anodic Filament (CAF) Failures of Electronic Circuits Ling Zou 16 July 2019 NPL Management Ltd - Commercial 4 You can book your next webinar at https://www.npl.co.uk/electronic-and-magnetic-materials/electronics-reliability-webinars About NPL … The UK’s national standards laboratory 36,000 m2 national • Founded in 1900 laboratory • World leading National Measurement Institute • 600+ specialists in Measurement Science • State-of-the-art standards facilities • 360+ laboratories • The heart of the UK’s National Measurement World leading measurement System to support business and society science building NPL Management Ltd - Commercial 5 NPL/EMM/Electronic Interconnects Research Areas NPL Management Ltd - Commercial 6 You can book your next webinar at https://www.npl.co.uk/electronic-and-magnetic-materials/electronics-reliability-webinars How we work: Bespoke Research and NMS . Bespoke 3rd party research and measurement • Mission extension consultancy and testing • Sn whisker behaviour • Replacement alloy testing • SIR & CAF testing • Condensation performance of components . National Measurement System – to develop capability – in collaboration with industry • Metrology for high temperature electronics • Coatings for harsh environments • High voltage SIR and CAF testing • Reliability of embedded components • Power cycling in low vacuum NPL Management Ltd - Commercial 7 How we work: Collaborative Research . Collaborative research • Multi-partner projects • Sn whisker mitigation • Condensation testing • UKRI (Innovate UK) • Recyclable electronic assemblies • Substituting Ag in electronic inks • High temperature interconnect materials • Protective coatings to operate at elevated temperatures • Cost effective high temperature substrates NPL Management Ltd - Commercial 8 You can book your next webinar at https://www.npl.co.uk/electronic-and-magnetic-materials/electronics-reliability-webinars How we work: Conditioning, Ageing, Stressing Conditioning, Ageing, Monitoring Analysis Stressing (before, during & after) . Thermal shock – air to air capability from -70 to . Mechanical shock testing - acceleration rate and 300oC, with programmable dwells and rates of shock pulse width accurately controlled and change of temperature of around 40oC per monitored using accelerometer and oscilloscope minute (typically used for fatigue life testing of . Hot mechanical shock testing – up to 250oC assemblies) . Shear testing of component attachments - . Temperature cycling – from -65 to 200oC, with degree of crack propagation and damage to programmable dwells and ramp rates of around solder joints or die attach, strength of the joint, 10oC per minute (typically used for fatigue life comparison of alloys, post thermal fatigue testing of assemblies) (typically used for testing joint formation with . Humidity bias testing – from 5 to 98% relative new platings, fluxes or finishes) humidity, -20 to 100oC with electrical bias to . Hot shear testing – up to 300oC 1000 V (typically used for electrochemical . Pull testing – up to 300oC reliability testing) . Solder joint reliability testing - low cycle fatigue, . Condensation testing – condensation using driven by the mismatch of the coefficients of custom platen to chill samples below dew point thermal expansion, solder joint cracking, of humidity chamber adhesive loss of glob tops and underfills, . Thermal ageing – up to 300oC delamination in multilayer boards and modules . Power cycling – multi-channel switching and . Reflow soldering - for sample build and monitoring of power devices using cooling simulated manufacturing conditioning platens to increase cycle time - Low Vacuum Capability NPL Management Ltd - Commercial 9 How we work: Monitoring Conditioning, Ageing, Monitoring Analysis Stressing (before, during & after) . Constant continuity monitoring – in-chamber monitoring of electrical continuity across up to 900 channels allowing simultaneous measurement for interrupts of >100 micro-seconds . Electrical monitoring – in-chamber monitoring using programmable multichannel switching systems for resistance and capacitance . Surface insulation resistance (SIR) – in-chamber leakage current detection, approaching pA, and resistance values, monitored continuously over test periods up to 1500+ hours . Conductive anodic filament (CAF) testing – in-chamber monitoring of printed circuit boards for leakage current due to conductive salts forming . Solvent extract conductivity - using a mixture of isopropanol and water to remove soluble contaminants providing a measure of the ionic contamination . Solderability testing - performed on solder pads or component terminations . Tin whisker propensity – electrical monitoring of tin whisker growth, measuring wetting force and time . Adhesion testing – coating adhesion measurement using pneumatic or customised pull testing NPL Management Ltd - Commercial 10 You can book your next webinar at https://www.npl.co.uk/electronic-and-magnetic-materials/electronics-reliability-webinars How we work: Analysis Conditioning, Ageing, Monitoring Analysis Stressing (before, during & after) . Micro-sectioning - High quality polished micrographs . Fourier-transform infrared spectroscopy with for various investigations, including crack detection and microscope capability - used to identify organic and grain structure analysis polymeric materials, using infrared light to scan test . Optical microscopy and image analysis – a variety of samples and observe chemical properties high resolution optical imaging and measurements . Electrochemical impedance spectroscopy - used for the systems characterisation of electrochemical systems and to . Scanning electron microscopy - for analysis of surfaces investigate mechanisms in electro-deposition, electro- with complex topography with a magnification of over x dissolution, corrosion studies and the study of 100,000, used to locate tin whiskers, examine biosensors intermetallic layers, investigate crack failure modes and . Surface Profiling – 3D micro coordinate and surface general failure analysis roughness using contact and non-contact methods . FIB (Focused Ion Beam) . Surface energy – drop shape analyser for measuring . Scanning acoustic microscopy - uses ultrasonic waves surface free energy reflecting or transmitting at material interfaces to study . Electrokinetic analyser - automated surface zeta buried solid interfaces of dissimilar materials and non- potential analysis of solids destructive detection of features such as bonded . Thermal analysis interfaces, delaminated interface, voids and cracks • Differential scanning calorimetry (DSC) - rapid . X-ray florescence - used to determine the atomic technique that measures the heat flow associated with content of material, screening for ROHS compliance, material transitions as a function of temp. and time thickness measurements and validation of solder • Dynamic mechanical analysis (DMA) - a versatile content technique used for characterising time, temp. and . Energy dispersive X-ray spectra – electron frequency dependent mechanical behaviour microscopes for image and elemental analysis • Thermo mechanical analysis (TMA) - used for . X-ray radiography – nano-focus X-ray inspection measuring dimensional changes in a material as a function of time, temperature and the applied force NPL Management Ltd - Commercial 11 Introduction . Why electrochemical reliability is important? . What are the main causes for electrochemical failures? . How to use the Insulation Resistance (IR) technique to monitor CAF failures at higher test voltages. Test design and results of CAF failures under different biases up to 1000 Vdc will be presented. Conclusions on the effect of bias on CAF formation. Potential new collaborative research project for CAF propensity up to 1000Vdc. 12 NPL Management Ltd - Commercial 12 You can book your next webinar at https://www.npl.co.uk/electronic-and-magnetic-materials/electronics-reliability-webinars Electrochemical Reliability . Achieving high reliability in service is the key issue in today’s high-density electronic circuits. Electrochemical reliability becomes more critical, as electronic circuits move to increased packaging densities, and also operated at higher voltages and in harsher environments (hotter/damper/ condensing). Electrochemical reliability failures are mainly caused by contaminants and bias under damper conditions, facilitating the electrochemical corrosion process that results in a loss of continuity/short circuits. 13 NPL Management Ltd - Commercial 13 Electrochemical Reliability . For powered circuit failures, voltage bias is one of the main driving forces . The corrosion process is initiated and accelerated by the voltage bias. Electrochemical failures are very sensitive to
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