National Physical Laboratory

Improving Electronic Reliability - Through Product & Process Qualification at NPL - Downloads of past webinars - 2017

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Condensation Failure & Improved Testing for Electronic Assemblies
Tuesday 14 November 2017

NPL has developed a new test method to control the rate of condensation on to printed board assemblies during environmental testing. The method provided considerable improvements on existing industry standard tests and NPL's Electronics Interconnection Group is currently running a multi-partner project to refine the test and fine criteria. This webinar provides an overview of the test methods and some results from other NPL SIR assessment projects in Europe.

Topics covered:  Review of existing test methods  |  Disadvantages of industry procedures  |  NPL condensation test benefits  |  Results of selected production trials

Electrical Metrology for Flexible and Printed Electronics
Tuesday 12 September 2017

The printed electronics market doubled from 2014 to 2015 and a similar growth has been predicted for 2016. To ensure high yield and reduced wastage, the development of metrology to evaluate the electrical properties and quality of printed devices is required. This method will need to be high speed and therefore non-contact in order to keep up with the manufacturing process. In this presentation, along with a discussion on metrology options for the printed electronics community, we discussed the development of our solution for high speed, non-contact electrical metrology of printed electronics.

Topics covered:  Introduction to us of printed electronics  |  Practical applications  |  Non-contact measurements of sheet resistivity  |  Comparison with alternative metrology options  |  Sensor optimisation for wide range of ink technologies

Electrical Performance of Organic Substrate Materials and Coatings Aged at High Temperature
Tuesday 11 July 2017

In this presentation, we discussed the evaluation of the performance of substrate materials and coatings to determine their suitability for operation in high temperature environments.

PCB materials with Surface Insulation Resistance (SIR) test patterns were aged at 250 °C for over 2,000 hours. During this test, the SIR and capacitance was monitored both along the surface and throughout the board at various locations. The effect on the ageing process on the dielectric breakdown strength of high temperature ageing on PCB materials and efficacy of protective coatings has been evaluated and is discussed. Optical inspection of micro-sections gave information regarding the oxygen permeation through the materials during the ageing process.

Topics covered:  Substrates materials  |  High temperature environments  |  Surface insulation and capacitor measurement  |  Impact of high temperature on coating materials  |  Microsection analysis

UV Inspection and Thickness Measurement of Conformal Coatings
Tuesday 9 May 2017

The lifetime and reliability of electronics made to operate in harsh environments can be enhanced by conformal coatings applications. These polymer based coatings provide a barrier to air-borne contaminants from the operating environment, thus preventing attack from moisture, aggressive chemicals, salt sprays, etc. The protection of discrete components mounted on PCBs, such as resistors, capacitors, packages and passive components, can be achieved by the application of conformal coating using methods such as dipping, selective robot coating, spraying and brushing.

Conformal coating should completely cover the assembly and provide a good cover of sharp edges and other contours. There are, however, no reliable non-destructive methods for monitoring the coating thicknesses on common problem areas on PCBs. We will discuss a novel, non-destructive, UV inspection system, capable of measuring the conformal coating thicknesses on step edges of components.

Topics covered:  Conformal coatings for the protection of electronic circuits - a brief introduction  | Common conformal coatings and application methods  |  Common issues with conformal coatings  | A review of common methods for conformal coating thickness measurements  |  Using UV tracers for monitoring conformal coating thicknesses  |  The theory behind UV tracers for thickness monitoring  | Experimental methods and materials  |  Equipment design  |  Results and discussions  |  Conclusions and future work

Techniques for the Characterisation of Printed Electrodes and Sensor Materials
Tuesday 14 March 2017

The ability to characterise printed electrode and sensor materials is important in both determining the best formulations for the intended purpose and also to understand the fabrication process which can lead to differing electrode responses. A range of techniques have been used at NPL to characterise printed inks in order to understand material behaviour and manufacturing variables. The combination of all these techniques allows sensor and electrode materials to be characterised and modified according to specific needs. The techniques described are based on:

  • Electrochemical Techniques, including:
    • Electrochemical Impedance Spectroscopy (EIS)
    • Cyclic Voltammetry (CV)
  • Surface Characterisation Techniques, including:
    • Scanning Electron Microscopy (SEM)
    • 3D Microscopy and Contact Angle measurements

Characterisation of High Temperature Component Interconnect Materials
Tuesday 10 January 2017

The UK's National Physical Laboratory (NPL) is being partnered with several end-users to better characterise alternatives for high temperature component interconnect to operate above 200 °C. Currently, for electronic assemblies to operate at high temperature, they must use a high lead solder or expensive gold based solder. NPL has been part of a consortia to successfully develop innovative materials specifically designed to offer a Pb-free cost-effective alternative.

This presentation summarised the work undertaken by the authors to develop and better understand this new family of electrical interconnection materials, including updated long-term reliability data. The project brought together a materials supplier (GEM – Gwent Electronic Materials), an end-user (MSL - Microsemi) and a technology research organisation (NPL) to jointly develop, test and implement in production, the solution based on silver-loaded silicone materials. This presentation focused on the testing and materials evaluation undertaken at NPL to determine the long term performance of these alternative materials, including high temperature ageing up to 300 °C, thermal cycling and damp heat testing. Details of the shear strength and electrical performance of interconnects between the substrates and components during the test regimes are given. The manufacturing process is outlined, including details of the test vehicles utilised. The processing temperature for the conductive adhesive is 250 °C, which offers additional advantages in potential improvements in component and substrate reliability compared to soldered solutions, which would typically be processed at temperatures above 300 °C.

Topics covered:  High temperature materials and applications  |  Development of materials for HT  | Reliability results from two projects  |  Long-term high temperature storage and mechanical testing  | Design issues and process failure s |  Future requirements and testing

Last Updated: 21 Jan 2019
Created: 11 Jan 2017


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