National Physical Laboratory

Improving Electronic Reliability - Through Product & Process Qualification at NPL - Downloads of past webinars - 2013

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Cleanliness Assessment Using Solvent Extract and Ionic Extraction to Improve Reliability
Tuesday 3 December 2013

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 touches on many important measurement topics: Test methods and test samples required for testing  |  International specifications  |  Correct sampling procedures  |  Typical results and common product failures  |  Listing of NPL related reports



Guide to Temperature Profiling for Wave, Reflow and Selective Soldering
Tuesday 29 October 2013

The Electronics Interconnection Group regularly conducts temperature profiling during their process studies and, in the past, produced one of the first temperature profiling guides. This was supported with a study into the impact of thermocouple positioning with each of the major profiling system providers.

Today, the use of temperature measurement and control for lead-free assembly is even more important due to the small margin for error associated with some components during soldering. An increased reflow temperature increases the degree of board and package warpage leading to many process defects. Profiling is also important with curing adhesives, coatings and underfill to prevent voids. Understanding the correct procedures for profiling is a key knowledge that every engineer should possess.

This webinar touches on many important measurement topics: Soldering process and the need for profiling  |  Thermocouple types and profile systems  |  Mounting thermocouples for best response  |  Soldering defects due to poor profiling  |  Typical profiles for wave, selective and reflow



Environmental Robustness: Measuring Performance Coatings and High Temperature Interconnects
Tuesday 3 September 2013

This webinar touches on two important measurement topics: evaluation of coating protection and measuring the performance of high temperature interconnects. Ranges of coating materials are now available with varied properties that can be selected for specific applications. The webinar discusses how the protection can be measured using SIR testing. The results highlight the importance of coverage. Another key performance indication is the adhesion strength of the coating to the substrate, and a newly developed test method is discussed, and where the adhesion challenges lie. Finally, measuring the whisker mitigation potential by coatings is presented.

There increasingly is a desire to place electronics in high temperature environments, down well applications for example. Sintered silver joints once formed with their high melting point offer an attractive solution to the interconnect issue. To date sintered silver is not offered as an interconnect solution for surface mount assembly, but has found applications in high power semiconductors. Measuring the mechanical performance and the fatigue properties of these interconnects is discussed.

This webinar covers: Coating protection and barrier properties  |  Coating coverage  |  Coating adhesion  |  Coating whisker mitigation  |  Sintered silver interconnect assembly processes  |  Sintered joint performance



Functionalisation and Applications of Nanomaterials for Electronic Applications
Monday 8 July 2013

In recent years Nanomaterials have attracted increasing amounts of attention based on their novel electronic, mechanical, chemical and quantum confinement effects. In particular, carbon nanomaterials such as fullerenes, nanotubes and graphene have been the focus of intense attention due to their exceptional electronic and mechanical properties. However, aside from the diverse suite of highly attractive properties of these materials it has become increasingly apparent that in order to successfully utilise these materials in real-world technological applications novel integration strategies between the nano and the macroscopic world will be critical to their application. In order to do this, the chemical functionalisation and thus compatibilisation of nanomaterials has been identified as a principle strategy towards this goal.

In this webinar, we introduce research concerning carbon nanotubes and their chemical functionalisation in order to facilitate self-assembly with nanoparticle materials. This strategy is highlighted as a viable means to directly control the assembly of hybrid nanomaterials. This is followed by the presentation of research concerning graphene and graphene oxide and the strategies of doping and chemical functionalisation in the context of electronic devices and mechanical composites. Following the enormous interest in 1D and 2D carbon nanomaterials, alternative materials have received much attention on account their electronic, mechanical and optical properties. The surface functionalisation of these novel nanotube and nanosheet materials is introduced and discussed in the context of their utilisation as electronic devices and their application as substrates, dopant, dielectric, and barrier layers for electronic devices.

This webinar covers: Perspective on Nanomaterials  |  Carbon Nanomaterials  |  Functionalisation and Application of Carbon Nanomaterials in Electronics  |  Inorganic Nanotube and Nanosheet Materials  |  Application and Metrology Considerations for Nanomaterials



Through Hole Reliability for High Aspect via Holes
Tuesday 11 June 2013

This webinar discusses the results of NPL's work on multilayer PCB reliability with particular emphasis on a range of factors that can reduce the time to failure after assembly. These include via proximity, laminate materials, exclusion of non-functional pads, surface finish, PCB thickness, reflow profiles, micro-vias and z-axis thermal expansion. Details of an intercomparison between thermal cycling and interconnection stress testing are also given.

This webinar covers: PCB multilayer via reliability  |  PCB board materials  |  Non-functional pads, via aspect ratios  |  Interconnection stress testing and thermal cycling  |  Intermittent via location



Reuse of Electronic Products
Wednesday 15 May 2013

This webinar discusses the ReUSE (Reuseable, Unzippable, Sustainable Electronics) project, an innovative printed electronics solution to increase the recyclability of electronic assemblies. The project partners (NPL, GEM Group and In2Tec) designed, developed and tested a series of unzippable polymeric layers which, while withstanding prolonged thermal cycling and damp heat stressing, allow the assemblies to be easily separated at end-of-life into their constituent parts, after immersion in hot water. The project demonstrated a 90% recyclable inverter circuit for an electroluminescent lamp.

This webinar covers: Printed circuit assembly recycling  |  Fitness for purpose testing of printed electronics assemblies  |  Reuseable, Unzippable, Sustainable Electronics



BGA Reliability - The Effects of Solder Joint Voiding and Uneven Stand-Off Height
Tuesday 30 April 2013

This webinar covers work undertaken at NPL on BGA reliability. The effect of voiding in BGA solder joints has been investigated and details of the project results are discussed. The effect of uneven solder joint stand-off height due to pop-corning in components has also been studied. Its effect on solder joint reliability has been measured and details of the project outcome are given.

This webinar covers: BGA voiding  |  Uneven BGA stand off height  |  BGA reliability  |  Thermal cycling and reliability



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



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

Last Updated: 26 Jan 2015
Created: 28 Mar 2012

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