Improving Electronic Reliability - Through Product & Process Qualification at NPL - Download videos of past webinars
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The Attraction of Sn Tin Whiskers
Wednesday 6 March 2013
The propensity of Sn whiskers to cause electrical shorts is well documented and has caused problems in a wide range of industry sectors. Work at the National Physical Laboratory has characterised two factors which may affect the likelihood of a whisker short occurring: electrical field strength and contact pressure.
Tin whiskers are attracted to electrodes of opposite polarity due to the electrostatic field generated. The nature and degree of the attraction force will be discussed and videos of the movement of whiskers under electrostatic attraction will be shown. Shorting is also more likely to occur when pressure is applied to a whisker in contact with a conducting surface, making it likely to conduct at a lower voltage than it otherwise would have. The electrical resistance of whiskers is also discussed.
This webinar covers: Electrostatic attraction of Sn whiskers | Increased shorting due to contact pressure | Voltage breakdown of whisker contacts | Electrical resistance of whiskers
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Benefits of Using Nitrogen During Soldering and Determining PPM Levels
Thursday 14 February 2013
Lead-free solder alloys that have replace eutectic tin-lead require higher soldering temperatures or are less solderable or both. However, raising soldering temperatures by that amount can lead to problems for components and to increased oxidation. The use of nitrogen then becomes a important question for industry.
It is likely that soldering will be carried out with a lower superheat - the difference between liquidus and soldering temperature - than is now standard. This lower superheat and the poorer solderability will reduce the process window and make using an inerted process more important. It is critical to determine how much inerting is needed. In the absence of production data, wetting balance studies can be used to compare the solderability of lead-free alloys and eutectic tin-lead solder as a function of superheat. The solders reported cover the near eutectic alloys - Sn/Pb, Sn/Ag/Cu, Sn/Ag/Bi, Sn/Cu and Sn/Zn. Residual oxygen levels were varied between 10 ppm and air and the superheat varied between 20 and 60 °C. The data can be compared with previous work using copper wires and coupons.
This webinar covers: Benefits of nitrogen in soldering | Processes using nitrogen | Changes in solderability based on temperature | How nitrogen benefits the process | What levels of nitrogen provide benefit
CAF Conductive Anodic Filaments - How To Avoid Failure
Tuesday 22 January 2013
Conductive Anodic Filamentation (CAF) is a subsurface failure mode for woven glass-reinforced laminate (FR4) materials, in which a copper salt filament grows and results in a consequential electrical short between plated through-hole (PTH) walls or adjacent copper planes. In this webinar we cover FR4 laminates, in the form of high PTH density multi-layer test circuits, exposed to different manufacturing conditions and studied for resistance to CAF initiation and growth. CAF performance was assessed using high temperature and humidity conditions to promote failures, with a voltage applied across adjacent vias. By application of a range of voltages and via geometries the basis for a performance map for laminates was obtained for use in materials comparison. The changes due to exposure of laminates to lead-free temperatures and other processing steps were then examined using the technique, and a number of important recommendations made regarding minimising the possibility of CAF initiation and growth. A new approach to characterise CAF processes has been developed using a Simulated Test Vehicle (STV). The STV, can be easily built under controlled condition in the laboratory using different glass fibres and resin power to investigating effect of different variables on CAF separately. The advantage of STV is described and examples of material studies that can be undertaken presented.
This webinar covers: What is CAF? | How does failure occur? | Testing techniques | Testing performance | Failure modes | Design and its impact on CAF
Practical Applications for Nano Electronics
Wednesday 10 October 2012
The extraordinary properties exhibited by metallic carbon nanotubes, which arise from their perfect self-organised crystal structure, make these materials attractive candidates for electrical interconnects. This webinar looks at methodologies that being developed for implementation of CNT interconnect systems, synthesised at low temperature, in accordance with the ITRS roadmap. Another key aspect for industrial take-up is the development of dependable tests of performance and reliability, which due to the unique material properties will require innovative metrology. The challenges in this area are presented and the possible solutions discussed, which will include electromechanical measurements.
This webinar covers: Properties of CNTs | Adhesion of CNTs to surfaces | Wetting of CNTs with solder | Conditioning of CNTs in order to improve adhesion | Reliability testing of CNTs | Health and safety: what are the risks?
Review of Life Cycle Analysis (LCA) Modelling in the Development of RoHS & WEEE
Wednesday 15 August 2012
Over the past 10 years, several environmental impact and life-cycle assessments (LCA) have been carried out to assess the material substitutions that have occurred after the introduction of the RoHS legislation. By taking a retrospective view, it has been shown that in many cases there is not a significant environmental improvement in the substitution of lead, and for certain factors lead-free solders have more damaging impacts. This webinar reviews the findings from a number of environmental assessments, and evaluates the need for a full life life-cycle approach to be taken before legislation committing industries to costly materials substitution is put in place.
This webinar covers: Metal cycles and issues with silver, bismuth and other elements | Uncertainty in leachate and toxicology measurements | Outcomes from LCA studies | Impact of lead-free on global warming potentials
Practical Applications for Printed Electronics
Tuesday 3 July 2012
Printed electronics has received much press in recent times but is a technology with many advocates and few current applications. Whilst printed devices on low cost substrates may be the future, printed flexible interconnect is viable today. However, market penetration is being handicapped by lack of consumer confidence in fitness for purpose. This webinar discusses how printed electronics can be used for reliable, flexible interconnect on thermoplastic substrates.
This webinar covers: Using printed electronics today | Potential application areas for printed electronics in the shorter term
Reliability of printed interconnect | Printed electronics and recycling
Effectiveness of Baking to Remove Moisture from Between PCB Ground Planes
Thursday 7 June 2012
With the introduction of Pb-free solders there has been in increase processing temperatures such that boards will have a greater risk of delamination in the reflow stage. To abate this risk, boards and components are baked prior to working to remove the internal moisture content. The flow of moisture is governed by the diffusion equation and moisture ingress and removal from ground planes has been experimentally investigated and modelled. Results show that moisture removal is often unfeasible and that in certain situations a baking regime may actually increase local moisture content under a ground plane.
This webinar covers: Capacitance measurements of moisture content | Moisture ingression under ground planes | Diffusion modelling | Plated and non-plated through holes | Effect of hole density | Effect of temperature on diffusion coefficient | Storage considerations | Listing of NPL related reports
Assessment of Re-terminated RoHS Components for SnPb Applications
Wednesday 9 May 2012
There has long been concern in some market sectors that tin finish on PCBs and component terminations can lead to product or system failure due to tin whiskers. This failure mode has been seen in the field and in many reliability experiments. Changing the solderable finish on components after supply has long been seen as a solution to tin being the most widely available finish but what is the impact and reliability of the re-termination process?
This webinar covers: NPL project overview | Characterising components before and after re-termination | Optical and SAM assessment of components | Thermal cycling of test assemblies | Mechanical and microsection analysis
Impact of Copper Dissolution in Lead-Free Manufacture with Different Alloys
Wednesday 4 April 2012
Copper dissolution from PCBs in molten solder always occurs but with the introduction of lead-free alloys the dissolution rate increased. This was due to the higher process temperatures and that the alloys were higher tin content, hence the copper was more soluble. Factors affecting the dissolution rate include alloy composition, temperature, copper type, flow speed of the solder and the structure of the exposed copper. Selective soldering with typically higher solder temperatures are of particular concern with erosion around the knee of the PTH.
This webinar covers: Dissolution process and the formation of the IMC | Impact of using different alloys | How to measure dissolution rates | Copper dissolution, what do you look for? | Listing of NPL related reports | Monitoring dissolution during fabrication and assembly in the following processes: Rework solder fountain; Selective soldering processes; Wave soldering; PCB solder levelling; Manual soldering / de-soldering; Reflow soldering
Using Mechanical Testing to Diagnose Design, Product & Process Failures
Tuesday 21 February 2012
Often when a product fails in the field or in the assembly process you need to use mechanical testing to demonstrate the cause or where corrective action has improved the weakness in the process. Microsections, shear testing, dye and pry and temperature cycling are just a few of methods than can be used, but which is best and will convince management and your design team that no more failures will occur?
This webinar covers: Test methods and samples required for testing | International specifications | Correct sampling procedures | Typical results and common product failures | Listing of NPL related reports
Characterisation of Solder Joints, Test Methods & Typical Failure Modes
Tuesday 24 January 2012
Solder joints are reliable in electronic assemblies provided they are designed correctly; the solder volume is controlled along with the correct selection of alloy and mating faces. Considerable testing has been conducted over the years by NPL to help define actual reliability data and modelling of solder joints. This expertise allows the EI team to define the best test methods to prove a product is fit for purpose.
This webinar covers: Test methods and test samples required | International specifications | Correct sampling procedures | Typical results and common product failures | Listing of NPL related reports
Cleanliness Assessment Using Solvent Extract & Ionic Extraction to Improve Reliability
Thursday 24 November 2011
Setting the correct cleanliness levels for electronics to prevent premature failure is extremely important, particularly in safety critical applications. Accurate determination of cleanliness to existing standards and the need to quantify contamination types has become more important in printed board manufacture and prior to conformal coating. Different measurement systems and techniques exist and can be used for clean and no clean processes to monitor your company's performance and potential process improvement.
This webinar covers: Test methods and test samples required for testing | International specifications | Correct sampling procedures | Typical results and common product failures | Listing of NPL related reports
Using Surface Insulation Resistance (SIR) to Qualify Production Processes & Materials
Tuesday 8 November 2011
Surface Insulation Resistance (SIR) is a long established technique for qualifying materials and processes in electronic assembly. SIR can be used to set up or monitor the reliability of an assembly process which may include solder paste and liquid fluxes in combination with conformal coating or with a clean or no clean process. The test method may also be used for other applications to improve long term product reliability.
This webinar covers: Test methods and test assemblies | International specifications | Test procedures and materials required to conduct the test | Typical results and common failure modes | Listing of NPL related reports
How to Test & Qualify Packages with Scanning Acoustic Microscopy (SAM)
Thursday 27 October 2011
Scanning Acoustic Microscopy (SAM) is a technique often used to examine electronic components for damage potentially caused by popcorning during soldering. It is a common failure analysis procedure which allows engineers to pinpoint the weaknesses of parts or demonstrate failure modes. SAM can also be used and this webinar shows you how it can assist your process engineers.
This webinar covers: Test methods and components required during testing | International specifications | Typical results and common failures found | Listing of NPL related reports
Solderability Assessment – Testing, Ageing & Practical Impact on Assembly Yield
Tuesday 11 October 2011
There are different techniques that can be used for solderability assessment; however, the wetting balance is the one scientific test which provides absolute results which can be compared with printed board assembly yields. Direct measurement of wetting is ideal for measuring changes in solderability on components and printed boards but there are other ways you can use this technique to improve yields and reduce costs.
This webinar covers: Test methods and PCB/component requirements for testing | International specifications | Typical test results and common failures found | Impact of ageing samples | Listing of NPL related reports
X-Ray Fluorescence Testing Results with Laboratory & Handheld Systems
Thursday 8 September 2011
RoHS raised the need to test materials and components for compliance with banded substances like lead in electronic assemblies. However, there are misunderstandings on how to test parts, the readings obtained and interpretation of meaningful results. The EI team have had direct experience with laboratory and handheld systems and utilise their experience in testing customers' products for compliance.
This webinar covers: Theory of XRF and test methods | PCB/components requirements for testing | International specifications
Typical test results and common test failures | Listing of NPL related reports
Tin Whiskers Evaluation Techniques & Benefits of Conformal Coating
Wednesday 22 June 2011
A considerable amount of resources have been invested worldwide into understanding how tin whiskers grow and the potential for failures in electronics. Over the last few years the EI team have undertaken many projects for customers on testing products, but more recently created a test vehicle which allows the assessment of materials and other processes like conformal coating as a possible mitigator to whisker failure.
This webinar covers: Theory of operation and test methods | Material or samples for evaluation | Specifications or codes of practice | Typical test results and common test failures | Listing of NPL related reports