Editorial

Citation

Goosey, M. (2008), "Editorial", Circuit World, Vol. 34 No. 4. https://doi.org/10.1108/cw.2008.21734daa.001

Editorial

Article Type: Editorial From: Circuit World, Volume 34, Issue 4

In this final issue of Circuit World’s (CWs) Volume 34, there are seven papers covering a wide range of topics that will hopefully be of interest. There is no focussed theme for the issue, but rather an eclectic collection of papers that highlights the many interesting facets of interconnect research and technology covered by the journal.

Regular readers will be familiar with the various pieces of European legislation, such as the RoHS Directive, that have impacted the PCB industry in recent years. The move to lead-free assembly has been mandated for many electronic products since 2006 and thus it might be assumed that the circuit board-related issues around the conversion to lead-free have long been resolved. While it is true that producers had little choice but to meet the requirements of the legislation deadline by converting their assembly processes to lead-free, there are still many issues that need to be addressed and which require further study. Work is, therefore, still being undertaken to broaden our understanding of the implications of converting to lead-free. This is clearly evidenced by the content of some of the papers included in this issue. For example, the paper by George Milad discusses circuit board solderable finish choices in the context of the move to lead-free and it is interesting to see how certain finishes that did not gain wide acceptance with lead-based solders are now receiving renewed interest for lead-free applications. Also on the subject of lead-free, Bo-In Noh and Seung-Boo Jung compare the electromigration performance of different solder alloys on printed circuit boards and they specifically compare the performance of a lead-free SAC alloy with the traditional tin-lead alloy. Again, the results make interesting reading and highlight the importance of gaining a fuller understanding of the implications of using new sets of materials.

Having worked its way through the issues of RoHS compliance, one might be forgiven for thinking that the PCB industry was now fully compliant with the current legislation. While this may partly be true, there is growing concern about the potential impact of the REACH Regulation, especially as it might bring about the demise of certain key substances used in the formulation of process chemistries and materials used in circuit board fabrication. The IPC recently (July 2008) published a report on REACH readiness in the PCB industry and one worrying finding was that there was “a distressing lack of understanding throughout the industry on the impact and scope of REACH”. There are also questions about how the RoHS Directive might evolve in the future within the broader context of the REACH Regulation and its list of substances of very high concern. Kate Geraghty has previously published a paper on the REACH Regulation in this journal and I am pleased that she has provided us with a new paper that details the present situation in the context of our industry. There is clearly a need for more information and help.

I am also pleased that we have been able to include a paper prepared by Joe Fjelstad, a well-known figure in the PCB industry and a member of the CW Editorial Advisory Board. Joe has provided a paper detailing the materials and choices that have to be made when producing flexible circuits. The subject of flexible circuits is often overlooked because of the dominance of rigid printed circuits and it is therefore good to be able to include such a paper. For those readers who wish to learn more about this fascinating sector of the interconnect industry, Joe has recently produced a third edition of his book on flexible circuit technology, and electronic copies can be downloaded free of charge from: www.flexiblecircuittechnology.com/third.php

Also on the subject of flexible circuits, this issue has a paper detailing the novel and innovative work undertaken by Babak Parviz and his colleagues at the University of Washington. This very interesting paper details the use of self-assembly at the micron-scale, as an attractive candidate for the integration of various functions onto unconventional substrates and for building high-performance flexible circuits. The work reported details their work in building functional parts such as transistors and light emitting diodes and their integration onto flexible plastic templates.

Flexible substrates also feature in the paper by Nurdan Sankir, which describes work on the selective deposition of conductive polymers onto flexible substrates and the tailoring of electrical resistivity by a post-deposition treatment. This novel approach has demonstrated the promising performances of polymer resistors made using this simple and low-cost fabrication method. It should be possible to integrate such devices into more complicated electronic structures, thereby enabling disposable electronic devices to be fabricated on mechanically flexible substrates.

The move to higher operating frequencies has been inexorable in recent years and circuit board designers have been increasingly forced to extract enhanced performance from high-speed transmission lines on FR4 and related substrate materials. Consequently, this has generated a need for a practical and robust test technique for loss that can be deployed on the shop floor. In the paper from Intel and Polar Instruments one such method, based on a technique known as root impulse energy testing, is detailed. The technique is easily deployed and offers repeatable, reliable discrimination between PCBs fabricated with a range of varying base material loss characteristics.

Finally, I am pleased to announce that, this summer, CW received its first Thomson Reuters (formerly ISI) impact factor. The 2007 impact factor was 0.292. Additionally, CW is now included in the Journal Citation Reports. This is great news for the journal and we hope to build on this important development in forthcoming volumes.

I hope you enjoy reading this issue of CW and, as always, I welcome your comments, feedback and suggestions. Please feel free to contact me at: m.goosey@lboro.ac.uk

Martin Goosey