EIPC 50th Anniversary Conference Day 1: The Past, the Present and the Future, Pt. 1

Estimated reading time: 16 minutes

The final keynote presentation came from Roger Massey, technology strategy and strategic marketing manager at Atotech, with a perspective on the changing shape of the HDI market.

He explained that HDI PCBs had evolved through three generations: originally subtractive technology with lines and spaces down to 60 microns, through any-layer technology with lines and spaces down to 40 microns, to modified semi-additive technology to achieve lines and spaces of less than 30 microns. Commenting that technology roadmaps, of which there were many, had historically served as useful educated guesses to indicate future interconnection density requirements, their predictions had largely been blown away by recent market developments in mobile devices. Handsets were becoming thinner and although screen sizes were increasing, there was less space available for the PCBs because larger batteries had to be accommodated. This was driving a technology shift towards smaller form factors and designs and pushing the HDI market for increased interconnection density by miniaturization of holes, pads and conductors to improve connection to the next system level, typically either an IC substrate or some form of direct chip attach, as well as the need to maximise electrical performance, reduce latency and increase signal speeds.

Sub-30-micron lines and spaces could not be achieved with panel plating techniques and needed modified semi-additive processing (mSAP) or advanced modified semi-additive processing (aMSAP). Copper foils as thin as 2 microns were required, with improved surface treatments to enable more efficient laser drilling of ultra-small microvias, and new lasers with picosecond and femtosecond pulses to minimise heat damage whilst achieving maximum via density.

Chemical process suppliers were developing innovative solutions to meet the current and future market needs. These included surface preparation and multilayer bonding treatments, small via desmear and high throw electroless copper for small microvias, copper plating electrolytes capable of via filling and pattern plating simultaneously, photoresist strippers and etchants capable of working with sub-30-micron lines and spaces, and final finishes to ensure solder joint reliability and electrical performance with smaller pad sizes.

Massey’s closing comment was: “The next five years are going to be very challenging—we as an industry can deal with that!”

EIPC vice-president Emma Hudson moderated Session 2, entitled European PCB History and Future, and invited Paul Waldner, managing director at Multiline International Europa and a former EIPC chairman, to look back over the past 50 years with a brief history of printed circuit board manufacturing in Europe.

Apologising that he had only been in the industry for 44 years, having started as a designer in the days of taped artwork, Waldner looked back even further, to the original invention of the printed circuit by the Austrian engineer Paul Eisler while working in England around 1936, and tracked the development of the technology and the European industry since that time, with a long list of notable names and events along the way. His presentation triggered many memories from elder statesmen of the industry who sat in the audience, especially when his old photographs challenged delegates to identify names, faces and occasions.

The decision to form EIPC had been made at the 1968 Electronica show, with the objective of representing the European industry’s needs in terms of culture, work ethics, technology and social-work interfaces. EIPC’s role grew to provide education and training to the industry, networking at all levels. and collaboration with standardisation bodies in the development of IEC standards. The first Printed Circuit World Conference was held in London in 1978, a joint effort between EIPC, ICT, IPC and JPCA.

By 1980, Europe’s printed circuit production had reached about $1.3 billion. By 2000, sales had grown to a peak of about $6.5 billion, and since then there had been a steady decline until about 2015 when sales levelled off at approximately $2.8 billion per year. Presently, HDI, flex and flex-rigid PCBs comprised 30% of European PCB production, and there were signs that output might begin increasing along with general world demand growth for PCBs in areas of low production quantities like medical, military, avionics, industrial and in high value circuitry utilising high speed materials and flex-rigid constructions.

Whereas Paul Waldner had looked back, industry analyst and strategist Hans Friedrichkeit looked ahead at technology drivers for the printed circuit boards of tomorrow. “Do you remember 2008 or the millennium? No problem! But what will our world look like in 2028?”

Friedrichkeit used many video illustrations to exemplify what was to come: “We live in a time of disruptive innovation in which existing technologies are quickly supplanted. Twenty-five years ago, the mobile phone made communication possible anytime, anywhere. Eleven years ago, the iPhone opened the smartphone era. The convergence of language, image and data with countless apps became reality. Nine years ago, Tesla launched E-Mobility with its Roadster. Currently the first fuel cell vehicles and even bicycles are on the road.”

About advanced driver assistance systems, he continued: “We will quickly get used to autonomous parking, traffic jam assistants and autonomous driving on motorways. The first driverless robotic taxis are in trial operation and in about seven years we will be able to drive autonomously to the front door.” He cited Mercedes’ Smart concept car, the Smart Vision EQ Fortwo, demonstrated at CES 2018, with no steering wheel, no pedals and operated by smartphone, as offering a new vision of urban mobility and efficient local public transport. Further in the future was an intelligent vehicle chassis with a detachable passenger pod that could be lifted and transported by a drone and placed down on another chassis in a distant urban location. “The future will be even more exciting and is coming faster than expected!”

The next presentation, from Pavel Gentschev, chief technical officer at Lackwerke Peters, discussed possibilities and experiences in achieving thermal management improvements with specialised coatings on printed circuit boards.

The U.S. Air Force Avionics Integrity Program had identified temperature as the principal cause of failure in its electronic systems, accounting for 55% of all failures investigated, and attributed to density of components, high power components and applications in areas with high ambient temperatures.

So how to manage the heat? Gentschev reviewed the theoretical principles of heat conduction and heat dissipation, thermal impedance and the significance of interfaces. He discussed how thermal interface materials could improve heat coupling and heat transition and how low-shear-modulus formulations could also help with thermal-mechanical decoupling at interfaces between materials with different thermal expansion characteristics.

He listed the limitations of thermal greases, thermal foils and gap pad materials, showed examples of printed thermal interface materials that could be screen printed by the PCB fabricator in layer thicknesses of 30 to 150 microns, and summarised the characteristics and selection criteria for thermal interface pastes. And whereas traditionally heat-sinks were bonded-on as separate components, it was practicable to use heat-sink pastes to print them directly onto the surface of the PCB, and if necessary to use them in combination with printed thermal interface pastes. He showed several application examples and the results of comparative thermographic measurements.

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