EIPC Winter Conference Review: A Focus on Miniaturization

Estimated reading time: 9 minutes

The theme of the first technical session of EIPC’s Winter Conference in Aix-en-Provence on Feb. 3 was “Miniaturisation and fine-line PCB production: From design to manufacturing.” The session was moderated by EIPC Vice President Thomas Michels, CEO of ILFA in Germany. The theme of the conference is “Driving the Future: Innovation, Energy, and Sustainability in PCB Technology.”

The opening presentation came from applications engineering specialist Dr. Roland Steim of Dyconex in Switzerland, who described how the company has addressed the challenges of miniaturisation and fine-line PCB production.

The general trend for more functionality and smaller size, and the need for efficient signal transmission in high-frequency and high-speed communication, has led to requirements for increasing layer count and/or increasing density of lines, spaces, vias and pads, together with more precise trace edges and smooth surfaces. Dr Steim said successful miniaturisation is not only about lines and spaces but includes consideration of thinner flex and rigid materials, improved bend-zone technologies for flex materials, fine-line production technologies and better registration, as well as a review of solder masks and surface finishes.

Examples of how material thickness can be reduced include using flexible resin-coated copper and thinner polyimide layers in flex constructions, as well as incorporating an additional conductor layer in the build-up. Bend radii could be reduced by pre-routing, depth routing, or laser ablation, depending on design complexity.

Dyconex has addressed the demand for finer lines by adopting additive technology. Their SAP process enables 80 micron pads on 110 micron pitch, with 8 micron lines and spaces, and two lines between pads.

Steim gave several examples of applications of fine-line circuits: cables, inductive positioning sensor coils, increased pixel density imaging, packaging for flip chip, and photonic ICs.   

Challenges in fine-line PCB production include seed-layer adhesion, inspection, and repair. Surface finishes have a significant influence on bending performance, with the brittle nickel in ENIG giving the worst results and nickel-free finishes being preferred. But perhaps the biggest challenges includes the need for investment in equipment, and increasingly fragile products demanding higher clean-room and production standards.

Dyconex achieved success on multiple projects in series production by addressing the sum of many challenges and has continued, together with their customers, on an ongoing learning curve to push the limits further.

Henk Berkel, senior application engineer at Multek in the Netherlands, discussed how new technologies are pushing interconnects to the next level of integration. He put a perspective on the current situation by referencing an overview of myriad integration options from Fraunhofer, who saw system integration as key to helping manufacturing companies to remain competitive in high-wage countries and defend their market leadership.  

Berkel commented that although certain “mature” integrated technologies, such as embedded resistors and capacitors, remained a small niche market, embedded copper coin technologies for thermal management have now become mainstream, especially in Massive MIMO applications in 5G and future wireless networks.

He sees artificial intelligence as a new world, remarking that AI data centres are extremely power hungry—up to 350 megawatts and more—before exploring the  complexity of NVIDIA devices and considering system densities and power consumptions. He believes that the surging demand for artificial intelligence and machine learning could lead to power losses that, from a cooling perspective, would be prohibitively expensive to manage. 

Looking ahead, he considered that although the incorporation of decoupling capacitors and MOSFETs directly into a single PCB substrate would significantly streamline design and reduce cost, the thermal and cooling implications require careful analysis, particularly with regard to manufacturing, cost, and system reliability.

Berkel described new packaging concepts such as CoWoP assembly (chip on wafer on platform PCB), where chip-plus-interposer is bonded directly onto an advanced platform PCB, using mSAP processing to embed the RDL interposer into the substrate-like PCB.

His final topic was humanoid robot technology, where many small electromotors need control and space is limited, and he listed key components and potential suppliers. There are many areas requiring specialist PCBs in the controller, perception, and sensing planes: main controller, coprocessor, vision processing unit, visual module, audio processing unit, inertial measurement unit, force/torque sensing unit, tactile sensor unit, and LiDAR control unit.

In closing, he said, “Innovation happens with a speed as never seen before, and tomorrow this presentation might need already additions!”

The theme of the afternoon session, moderated by EIPC Vice President Emma Hudson, was “PCB manufacturing process automation and new flex circuit solutions.”

The first presentation, “Achieving Strategic Autonomy in PCB Fabrication,” was given by Alex Stepinski, CEO of Smart Factory Design in Poland.

Having previously designed six OEM PCB fabs and currently designing two more, plus two merchant-market fabs in design and two more projects in investment planning, Stepinski was well placed to provide meaningful advice.

He recognised two categories for PCB fab investment: strategic and competitive, and observed that 50% of new Western fabs are built as strategic cost centres for OEMs, whereas Asian fabs are typically designed to be globally competitive.

Comparing labour rates between China and the U.S., his experience was that to fill one direct labour position in China requires 2.3 heads on a 24/7 basis, at a base rate of $4–5 per hour. In the U.S., to fill one direct labour position requires at least five heads on a 24/7 basis, at a base rate of $18–24 per hour. So, the U.S. fab has the burden of training and administration of 2.5 times as many people at four times the base rate. Added to this, off-shift is very difficult to find, and even if available, requires significant premiums, resulting in the effective base rate rising to five to eight times the cost in China. Europe generally has lower or equal rates to U.S. sites, but higher overhead per head.

For PCBs, the bill-of-materials is historically 5–20% of the selling price, and complex fabrication costs are usually more driven by the bill-of-process and yields. Laminate and prepreg are primarily manufactured in Asia and are subject to tariffs and logistics costs to reach Europe. Stepinski suggested focusing on bill-of-process optimisation and building complex products to minimise this indirect bill-of-materials effect.  

In a greenfield situation, with all else equal, labour and bill-of-materials differences have resulted in prices 5 to 10 times higher than in Asia. Reducing this difference could only come from higher capital-asset and labour productivity. Stepinski’s experience is that cost reduction is best achieved by detailed planning of process efficiency, labour efficiency, and product-mix optimisation, with digital-twin simulation of the full fabrication process and real-product due diligence, before committing to bricks and mortar.

The brownfield challenge is much more complex, and first-principles implementations are hard to realise if established organisational structures require major change to support a new model. Moreover, first-principles approaches often increase costs in brownfields due to heightened interface requirements to legacy software and product-handling schemas. Changes typically need to be implemented by an overall project manager with competency in all silos being optimised, and never from within a given silo. 

Stepinski outlined the structure of high-capex/low-opex models being implemented, with a focus on first-principles process design and aimed at high return-on-investment and increased growth. He is an advocate of autonomous work cells for single-piece flow, together with the use of CAM-based digital twins to centralise all recipe decision-making. He observed that integrating PCB fabrication and PCB assembly could yield significant synergies by eliminating costs associated with the interface. 

He quoted performance results from Western first-principles projects: a 50-panel per hour high-mix double-sided production in the U.S. at 60% lower opex than Asia and three-year full-capex ROI, and a 390-panel per hour 8-layer production in the U.S. at 45% lower opex than Asia and three-year full-capex ROI.

Defence and aerospace and AI server cards are product areas currently being targeted to achieve growth in the U.S. Stepinski commented that the AI server fab market is forecast to grow from $3 billion in 2024 to $27 billion in 2027.  

How long is a flexible circuit? Markus Voeltz, director of business development in Europe for CEE PCB in China, gave us a hint in his presentation titled, “Superlong FPC: enabler of new battery technologies for e-mobility and energy storage.”

Voeltz detailed some of the new demands being placed upon batteries and their management systems as e-mobility becomes increasingly prevalent, with onboard voltages of 400–800 in series production, and up to 1,500 in development. He explained that, as an enabler of new battery technologies, the flexible printed circuit (FPC) being established as the standard for wiring due to its weight, tolerance compensation, component capability, and improved assembly.

Rising voltages and higher operating temperatures, and the need to transfer power as well as data signals, imposed additional constraints on the FPC in terms of the temperature and ageing resistance of materials, together with robust design features and layout requirements such as heavy copper, increased conductor spacing, and additional EMC shielding. Effectively, e-mobility creates entirely new requirements for printed circuits, and FPCs offer a meaningful alternative to cables and busbars.

Reliability and safety are serious considerations. In terms of fire hazard, Voeltz emphasised that electric cars do not burn more frequently than combustion engines but fires appear more spectacular, require complex fire-fighting, and they attract media attention. Technical power components and battery management systems require increased attention in design.

Voeltz summarised the functions of the FPC in e-mobility applications: contacting the cells directly or by means of nickel tabs through welding, acting as a carrier for temperature sensors, and providing highly accurate overload protection via surface-mounted fuses. The goal is one FPC per battery block.

Reviewing the manufacturing and assembly processes at CEE’s factories in China, which are largely roll-to-roll for FPCs, enabling lengths of up to 2,500 mm, he explained the dimensional compensation techniques they employ to maintain registration tolerances.

His concluding statement was that the market for batteries and their management continues to grow: fast, complex, and technically sophisticated.

Following the technical session, delegates departed the conference and boarded coaches which took them on a half-hour journey to Cadarache for a privileged visit to the ITER project, currently under construction. After security clearance, and wearing hard hats, hi-vis jackets, and safety glasses, the EIPC group had a guided tour of the assembly hall and construction site.

ITER, the International Thermonuclear Experimental Reactor, is one of the most ambitious energy projects in the world today, where 34 nations are collaborating to build the world's largest tokamak, a magnetic fusion device that has been designed to prove the feasibility of fusion as a large-scale and carbon-free source of energy, based on the same principle that powers our sun and stars.

Back to Aix-en-Provence for a splendid conference dinner and networking opportunity at La Rotonde, then a good night’s sleep ready for an early start to the second conference day.