EIPC Winter Conference 2024, Day 2: A Closer Look at Global Trends

Estimated reading time: 9 minutes

The EIPC Winter Conference 2024 took place Jan. 30–31 at the IHK Academie in Villingen-Schwenningen, Germany. The keynote session and first-day conference proceedings are reported separately. Here is my review of the second day’s conference proceedings.

The opening session of the second day’s conference proceedings focused on global PCB trends and was introduced and moderated by Dr. Michele Stampanoni, vice president of strategic sales and business development at Cicor Group in Switzerland. He opened the session with Dr. Hayao Nakahara’s knowledgeable and enlightening video presentation on the IC substrates industry. I included a summary of this in my review of the keynote session, but for completeness I repeat my notes here:

Nakahara began by observing that 2023 was a disappointing year for semiconductor, but that recovery is expected, which is good news for IC substrate makers.The long-term perspective is bright, particularly in automotive and industrial applications. 

The statistics indicate that personal computers and smartphones consume more than 60% of semiconductor devices so that “when PC and smartphone sneeze, semiconductor catches cold,” which is what happened in the latter part of 2022 through the first half of 2023. He believed that for PCs, the longer term is not so bright, but because more powerful artificial-intelligence-based processors are coming, the prospects for IC substrates are more positive. Indeed, the capacity for manufacturing Ajinomoto build-up film (ABF) is being increased. He commented that tablet shipments show a similar trend to PCs but smartphone shipments have finally started to rise. 

In China, iPhone sales have been overtaken by Huawei whose Mate 60 Pro is powered by a chip that uses 7 nanometre technology, developed and fabricated in China, and an indication of China’s rise in IC capability which has prompted huge investment for high-end IC substrate manufacture in China.

Although total car shipments have remained fairly static at around 83-84 million units over the past several years, electric vehicle shipments have risen sharply, with China leading the world. The number of semiconductor devices per car is estimated to be between 150 and 200. Multiply by x1.5 for hybrid cars and by x2 for electric, taking the total to a possible 400 of which between 30 and 40 will be main processor chips needing advanced packaging. Advanced driver assistance systems and autonomous vehicles will require many more.

Against this background, Nakahara focused his presentation on IC substrates. He listed the world's top 25 PCB makers and highlighted 15 that make IC substrates, some of whom make only IC substrates. He estimated that in 2022, IC substrates accounted for 18.6% of the total worldwide PCB production valued at about $97 billion. His forecast for IC substrates was $18.5 million for 2024 and $22.2 million for 2025. 

He commented that IC substrate makers and hopefuls sense the future growth of semiconductor chips, $200 billion investment being made by Intel, AMD, NVIDIA, TSMC, Samsung, Micron and others, and have started to invest about $30 billion in the expansion of existing IC substrate manufacturing plants and building new plants. He went on to list IC substrate investments being made by Japanese, South Korean, Taiwanese, and Chinese manufacturers, together with the package types they were preparing to make. For flip-chip BGA, LGA, and PGA, the build-up conductor layers are fabricated by semi-additive processing using mainly Ajinomoto ABF dielectric film. Flip-chip CSP is fabricated using mainly BT dielectric. There is still a considerable amount of wire-bonding substrate made for analog and power devices. 

Nakahara’s closing slide was a photograph of Dr Hamid Azimi, captioned “Next Challenge: Glass Interposer.” Food for thought.

“Does China+1 actually work?” was the question that Manfred Huschka, from  Manfred Huschka Management Consulting (Shenzhen), set out to answer. He explained “China+1” as a supply-chain diversification strategy by which some multinational companies seek to reduce risk and minimise their dependence on China by exploring alternative manufacturing and sourcing options in countries such as Vietnam, Thailand, Mexico, India, and Malaysia, in addition to China. It began about 10 years ago as the cost of labour in China began to rise sharply. Some companies adopted the approach, while others remained unconvinced of its value.

Currently, because of geopolitical tensions and further increases in Chinese labour costs, there is a resurgence of interest in de-risking the supply chain 

However, Huschka observed that China has built a complete supply ecosystem, with entire industries and their own supply chains being based in specific regions, with established and well-trained workforces and a high standard of transport infrastructure. He commented that large planned investments are getting shifted to other countries, quoting the example of a major Chinese electronic components manufacturer announcing that a multimillion-dollar expansion earmarked for India was being transferred to Vietnam. U.S.- and Europe-based companies are investing in manufacturing plants for IC substrates in Malaysia. He listed dozens of PCB manufacturers and PCB equipment and material suppliers set up in Thailand. 

He queried how successful those factories would be, because the market is not there except for IC substrates. Existing overcapacities in China have already resulted in dumping prices, and he remarked that, despite government subsidies, Thai PCB companies face an uncertain future. Compared with China, there is a shortage of general operators and engineers, and their attitude to work is different. There are water supply and infrastructure issues. If main factories in China suffer from lack of orders, how much business are they willing to transfer to their subsidiaries abroad? 

Huschka considered that the trend to build factories outside of China will continue, although it will be a long road to success and will cost a lot more than initially planned. In the long term, the additional capacity will cause only a small dip in China’s global PCB share and China will remain the leading PCB production producer, but with an increasing emphasis on value-added products. His advice is to continue to work with your current suppliers.

Rico Schlüter from RS-PCB Solutions in Belgium moderated the session on high-speed PCBs, and his first presenter was Herman Reischer, MD of Polar Instruments in Austria. He described the evolution of Delta-L methodology for measurement of PCB insertion loss since its original introduction by Intel, who had compared the accuracy and efficiency of different characterisation methods. They had been seeking a simple way to determine loss without complex de-embedding algorithms, and results from Delta-L have been shown to be accurate and consistent with those from established Thru-Reflect-Line and Smart Fixture De-embedding methods. 

Emphasising the importance of reference planes and the errors that could result from not de-embedding via effects, he introduced the Two-Line Delta-L method for direct through-measurement of insertion loss with examples of test panel design and footprint geometry. 

He illustrated software for generating Delta-L 4.0 test coupons with structures of 10-inch lines and 5-inch lines that allow the relationship between “Effective Er” and frequency to be determined and showed photographs of an actual test probe and a vector network analyser for insertion loss measurement, designed to enable PCB fabricators to make accurate and repeatable measurement of Delta-L 4.0 values.

Théo Morel, from Circuit Foil in Luxembourg, explored new challenges in the development of the next generation of ultra-flat ED copper foils for high-speed digital and radio-frequency applications. 

After a brief overview of the principal stages of foil manufacture—electroplating followed by the sequence of nodulation, passivation and silane-treatment finishing, processes—he reviewed the skin effect. The higher the frequency, the more tendency for the signal to be carried in the outer layer of the conductor, and the rougher the surface, the greater the insertion loss. So, to minimise insertion loss, the solution was ultra-low-profile foil. Morel showed photomicrographs of foils at five stages of development of the nodular “treatment” process with progressive reduction of nodule size, through “nano-nodule” to “nodule-free.” He then demonstrated how optimisation of the drum surface and the use of levelling additives in the electrolyte reduced roughness in the base foil at the primary electroplating stage. Other additives were used to control grain size and grain orientation, both of which influenced electrical conductivity. The effects of roughness and conductivity on loss could be simulated by finite element modelling. 

A new treatment has been developed which enables the same insertion-loss performance as no-profile copper foils to be achieved at frequencies up to 56GHz.

In conclusion, Morel made it clear that all of the component layers of the foil— microstructure, roughness, nodular treatment, passivation, and silane treatment— must be considered and optimized in the development of next-generation materials and that the optimization must be conducted in co-development with next-generation resin and prepreg materials.

The final presentation in the high-speed PCB session was given by Sanghwan Lee, senior engineer in the rigid materials development team at Doosan Corporation Electro-materials in South Korea, on advanced materials for high solder reliability. 

He remarked that the implementation of compact designs requires the use of ultra-thin substrates and high-reliability non-glass-fibre materials with low thermal expansion and low-loss properties. And the requirement for such materials is increasing.

He summarised the important structural characteristics of copper-clad laminates, particularly those key factors that determined dielectric loss and conductor loss, and demonstated the relationship between signal loss and frequency. From a mechanical point of view, he demonstrated the effects of resin content, glass transition temperature, and z-axis thermal expansion coefficient on reliability at higher operating temperatures, particularly in stacked-via configurations. Resin chemistry has a significant effect on physical and electrical properties, and he compared the benefits and limitations of a range of currently-used materials.

He looked at the impact of material warpage during the assembly process, particularly when there were differences between between main boards and interposers that could lead to cracking of solder joints, and he showed examples of the layer construction of various automotive control units and data communication systems. Solder joint cracking resulting from warpage and CTE mismatch issues can be mitigated by the incorporation of stress-relaxation outer layers in the multilayer construction to relieve physical stress on the joints. Lee described the properties of a special low-modulus prepreg available from Doosan, together with cross-sections of typical builds and the results of reliability testing.  

Lee considered the attributes and limitations of resin-coated copper when used as a basis for HDI multilayer builds in terms of finished thickness, reliability, laser drillability, fineness of lines and spaces, and dimensional stability. Resin-coated copper scored over woven-glass reinforced laminate in all areas except dimensional stability. A 10-layer construction based on a laminate core with four resin-coated-copper build-up layers on each side, patterned by mSAP with 30-micron lines and spaces, had been successfully evaluated as a smartphone main board by a leading manufacturer.

The session on printable technology was moderated by Johan Pellicaan, sales manager with MacDermid Alpha in the Netherlands. He introduced Celia Wenzler, director of PCB technology at Notion Systems in Germany whose topic was “What is inkjet?” and whose presentation broadly covered the subject from the generation of individual droplets to final applications in functional printing.

“What can inkjet do?” Nominating three elemental areas—the ink, print head, and final application to the substrate—she considered the details of each. She explained that if all these components are coordinated, final properties can be controlled and adjusted to offer an enormous range of functional applications. There were examples in the fields of electronics, optics, active layers, resists, adhesives, and encapsulants, together with the manufacture of three-dimensional precision components. 

She explored the capability of inkjet to create new and advanced solder mask features, compared with conventional techniques, and demonstrated some examples of the added value that could be realised. Her list of attributes included: matte or glossy effects, branding and the incorporation of legend, 3D features such as printing walls, distancers, barrier walls, mechanical supporting structures, encapsulation, and individualisation.  

She used a specially designed test pattern to demonstrate the capability of inkjet to apply different thicknesses in different areas, and to produce lines as fine as 40 microns. By printing walls or barrier dams around component footprints, the flow-out of underfill, conformal coating, and glob-top coating processes could be contained. 

Print-strategy data could be processed to incorporate copper-image information as well as solder-mask-image information, with filters that enabled a customised output controlling which copper or laminate surfaces were coated and which were free of solder mask, together with what ink drop density to apply. Significant savings in ink consumption could be made by placing solder mask exactly where and at what thickness it was required.

Continuing the inkjet theme, Milena Fritz, CEO of SAT in Germany, discussed current applications and future opportunities for on-demand inkjet printing in PCB and other industries. She emphasised the benefits of the additive process, both for solder mask and for flexible coverlay, particularly its higher flexibility in placing the ink only where it was needed. Being a digital imaging system, inkjet offered better flexibility in its ability to change the image data immediately before printing, as well as being eco-friendly with less pollution and no waste material. It also offers cost savings in production time and energy consumption. 

The inkjet process does have some physical limitations, one of which is capillary effects at the edges of etched copper features, which she illustrated with a video. She discussed raster resolution in terms of drop size and pitch between successive drops, and showed how flow-out could be controlled by part-curing on-the-fly with a UV lamp attached to the print head. Typical print strategy for covering larger areas was to first define the edges by printing barriers, then coat the areas needing more ink, before finally filling-in everywhere the design required. She showed photographs illustrating the results.

Applications of inkjet printing in PCB manufacture included etch resist, plating resist, solder mask, legend, and direct metal ink printing. She also showed examples of metal engraving, stencil cutting, and flexible circuit coverlay. 

The closing session featured a new introduction to the conference programme: a “Quick Fire Walk In” moderated by Alun Morgan, with a panel comprised of Thomas Michels, Kunal Shah, Alex Stepinski, and Celia Wenzler.  

Panel members responded to a range of questions including challenges facing PCB producers in Europe, access to finance for new technology in Europe, the energy cost disadvantage of European PCB producers versus the rest of the world, sustainability and cost benefits of nickel-free gold processes, capability, economic and sustainability benefits of the additive process, key challenges in qualifying and ramping-up additive printing, key drivers for zero-liquid-waste systems and how are they better than existing waste treatment systems. 

In his closing remarks, Morgan remarked upon the outstanding success of the conference and thanked everyone who had participated, with special credit to Tarja Rapala-Virtanen for coordinating the program and to Kirsten Smit-Westenberg and Carol Pelzers for their professional organization and management of the event. 

And once again I offer my personal thanks to Alun Morgan for providing superb photographs.