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Krishnanunni discussed current and future issues in PCB technology from the viewpoints of the designer, the fabricator and the assembler. Fine pitch component packaging demanded improved routability and higher interconnection density, using finer conductor geometries whilst keeping layer count to a minimum by cost-effective any-layer via-in-pad design rules. For maximising assembly yield, a critical factor was precision of solder paste application, and this was heavily influenced by the effect of PCB and solder mask topography on the consistency of contact between PCB feature and stencil. Established PCB fabrication techniques were approaching their capability limits and new methodologies were required. These were being explored in the Pitch Perfect KTP, a project with the objective of developing an ultra-high-density-interconnection fabrication technology compatible with a broad range of substrate materials, with low-cost interstitial vias and the potential for 25-micron lines and spaces, using low-impact surface modification techniques to minimise surface morphology. Although at the present stage of the project, IP considerations prevented her from disclosing practical details of process procedures, the technology would integrate straightforwardly with current process infrastructure, incurring minimal additional capital expenditure, and would be compliant with appropriate IPC standards.
Final presentation of the day came from Stuart Dalrymple, senior project manager at C-Tech Innovation, who reported the outcome of the REPRIME project, which had carried out research into the application of ultrasonics to replace poisons and explosives used in industrial metal finishing processes.
The project was funded by the UK Home Office, who wanted to find a technology-based instead of legislative solution to the perceived threat of chemicals held in relatively insecure conditions in small-to-medium companies being misappropriated and used to support terrorist activities. The objectives of the REPRIME project had been to overcome barriers to the adoption of cyanide-free technology, to demonstrate cyanide-free zinc and zinc-nickel plating on an industrial scale, to extend the work to cyanide-free copper, gold and silver plating, to reduce hydrogen peroxide use in the printed circuit industry and to ensure that the technology could be easily and cheaply retrofitted to existing equipment.
Referring to previous collaboration in the Susonence project, an EU Eco-Innovation Initiative, which had demonstrated that ultrasonics could be successfully used to replace chromic acid in the etching of ABS polymers, to improve the efficiencies of barrel plating in general metal finishing, and de-smear and copper etching processes in PCB manufacture. Dalrymple described how the use of ultrasonics had enhanced the deposition rate of cyanide-free zinc electroplating plating chemistries and improved coverage and distribution on complex shapes. It had also been shown that ultrasonics enabled the use of reduced concentrations of hydrogen peroxide in etchant solutions used in PCB manufacturing, and gave improved bath life with reduced frequency of replenishment and no adverse effect on downstream processing. The REPRIME project had been successfully completed, and was being rolled out to industry with continuing support from the Home Office, the Surface Engineering Association and the Institute of Circuit Technology.
In his closing remarks, Alun Morgan thanked the moderators and speakers for their contribution to an interesting, interactive and entertaining conference and networking experience, and delegates for their attention and involvement. He acknowledged the generous support of the sponsors, Viking, Isola, Polar and Ventec, and extended particular thanks to Kirsten Smit-Westenberg and Sonja Derhaag for their impeccable organisation and management of yet another highly successful EIPC event.
Click here for the slide show of the event. Read about Day 1 here.
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