EIPC Summer Conference 2016, Day 2: Strategies to Maintain Profitability in the European PCB Industry

Estimated reading time: 23 minutes

Stepinski made the point that closed loop systems effectively gave an unlimited water supply, so there was no need for water conservation, and much higher flow rates could be used for improved rinsing. The strategy then became one of budgeting contamination as opposed to budgeting water usage.

By putting all of these principles into practice, Stepinski had achieved a reduction of 80–90% in direct operating costs for chemical process systems compared with a conventional process, and the site was the first PCB production facility in North America to have all of its permits waived. The wastewater system was automated to the point of requiring only 10 hours per week of total labour. Total capital expenditures for all the chemical recovery systems associated with this project was $1.4 million, and costs would be lower in a brownfield site where existing equipment could be repurposed.

The final technical session was entitled “Tooling and fabrication experience with advanced technologies,” and was moderated by Martyn Gaudion. His first presenter was Mehul Davé, CEO of Entelechy Global, who made a convincing case for outsourcing CAM engineering. (Curious about the origin of the company name, I googled it and learned that “entelechy” means “the realisation of potential.”)

Why outsource CAM? In every PCB fabrication facility, there was increasing pressure on the front-end engineering department, more part numbers, more quick-turn requirement, more quoting activity, a greater focus on high technology and a customer expectation of fast response—all driving the need for off-shift pre-engineering and engineering capability.

A whole range of functions could be successfully outsourced, including quote-data processing, pre-CAM, CAM and post-CAM, and not just for the simple jobs - the right partner could handle complex high layer count HDI designs with controlled impedance and buried components, as well as flex and flex-rigid. There were six key areas of impact: on-demand capacity, improved automation, faster turnaround, reduced cost, improved quality and the ability to build redundancy in critical areas. The biggest benefit was flexible capacity, reducing overtime or the need to hire off-shift engineers. Automation was the key to efficiency, quality and reliability, and outsourcing reduced the need for dedicated staff to develop, support, and update automation. The time zone difference between India and Europe or North America was a benefit in that jobs sent in the afternoon would effectively be engineered overnight and be ready to go into production the following morning. Outsourcing gave access to higher quality talent, without employee overhead expenses or vacation costs, and reduced infrastructure costs. Outsourcing required documentation and systematic standardised processes, with consequent improvement in quality. Furthermore, having an offshore team ensured that “tribal” knowledge no longer resided in one or two key individuals who could leave the company and take the know-how with them.

The ubiquitous Alun Morgan came forward again, this time as European representative and project facilitator for the High Density Packaging User Group (HDPUG), to report the results of the HDPUG PWB Back Drilling Project. He explained that controlled depth back drilling of plated through holes was increasingly used in high speed designs to remove redundant copper which caused attenuation losses and made it difficult for a digital receiver to ascertain whether the received signal was truly a logic “one” or a logic “zero.” The critical parameter was the length of the remaining copper via stub from the targeted inner layer pad. Stub length design rules were driven by electrical requirements, not necessarily based on PWB reliability data or fabrication capabilities, and there appeared to be an increasing number of reliability issues attributed to back-drilling. So the project had set out to quantify the relative reliability of back-drilled holes to PTH holes, in terms of drill depth, hole and pad size and pitch, and to develop test coupons and measurement methods.

Some interesting observations had been made, particularly that normal PTH vias failed before back-drilled vias under thermal cycling, and there appeared to be a counter-intuitive hierarchy of design failures, with shallow back-drilled vias failing before middle and deep back-drilled vias. Morgan reverted to old-fashioned teaching aids and drew pictures on a flip-chart in response to requests from the floor to explain the failure mechanism, which in the event actually appeared quite logical.

A programme of IST testing in cooperation with PWB Interconnect Solutions had quantified the relationships between reliability and design rules, and verified the interconnection failure modes. Whereas normal plated-through vias tended to fail in tensile stress by barrel cracking, back-drilling effectively removed one outer-layer anchor and transferred thermal cycling stresses from tensile in the barrel to shear at the barrel-to-inner-layer-pad interface, resulting in bending of the copper pad and eventual cracking of the internal foil.

A non-destructive test for stub-length measurement, based on time domain reflectometry, had been developed in cooperation with Introbotix. This gave repeatable results that correlated well with microsection data, and the technology was applicable to both low-volume probing and robotic high-volume probing.

An example of cooperation between academia and manufacturing industry was demonstrated in the presentation from Anjali Krishnanunni, a KTP Associate/Project Officer at Coventry University and currently based at Stevenage Circuits. She explained how Innovate UK, the UK's innovation agency supported Knowledge Transfer Partnerships (KTPs) to assist businesses in gaining a competitive edge through better use of knowledge and technology.Page 4 of 5

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