EIPC Winter Conference 14 & 15 February, Milan
Conference Day 2
After the papers of Day 1 the delegates were hosted at a reception and plant tour of Elga Europe at their nearby production facility.
Georgio Favini, CEO, explained that Elga was founded in 1973 and had had three important joint ventures in its history, firstly with Lea Ronal then Tokyo Ohka and currently with Eternal. Favini explained that Elga Europe is the European leader in dry film photoresist for PCB fabrication being the only remaining European producer and having a capacity of 15 million Sqm/Year.
The dry film production process was then described in detail and the delegates were treated to a comprehensive plant tour seeing all the stages of manufacturing through mixing, coating, drying, in-line inspection, testing and slitting. The delegates were very appreciative of the hospitality shown by Elga Europe and felt privileged to have been shown around such an impressive facility by such knowledgeable staff.
The delegates then went back to downtown Milan for a gastronomic dinner in the very chic deli/restaurant “Eataly”.
Suitably refreshed after the excellent networking dinner the delegates took their places for day 2 of the programme.
The opening session entitled “New developments in PCB Technology, DFM and Cost Effective Supply Chain management” was chaired by EIPC Board Member Michele Stampanoni, who introduced the first speaker Robrecht Belis of Elsyca Belis introduced a PCB plating performance simulation system allowing plating layer thickness distribution prognosis before the start of production. Belis explained that the PCB plating process is very sensitive to panel size, pattern, holes, plating infrastructure and the electrolyte. The system developed characterises the plating process using infrastructure and electrolyte data and then utilises the specific circuit design to build a simulation of plating distribution. Belis went on to describe how design modifications, copper balancing and layout optimisation can then be performed prior to production starting. Belis concluded with a case study carried out at EuroCircuits where he demonstrated the resulting optimised layout, time savings and better quality deposition uniformity over manual techniques.
Roland Valentini of Gardien Group was next to present on the topic of “The Impact on supply chain management, final PCB yield and profitability”. Valentini started his presentation from the premise that there had been a major change in the Industry from analogue to digital and that this had brought new challenges for manufacturing and test. He further argued that traceability is going to be one of the key requirements to fulfil in high reliance markets, identifying the sectors as automotive, space, aerospace and military, medical, industrial, network and 5G base stations, mobile communications and home automation. Valentini went on to describe the Gardien managed supply chain process whereby the supply chain between the purchasing manager and the PCB fabricator is kept as lean as possible with non-added value steps being eliminated. The presentation concluded with a Chinese PCB sourcing example with the potential to effectively double the number of potential PCB suppliers and a description of the Gardien test service to the PCB industry to improve quality, reliability and total productivity.
The last paper of the session was presented by Markku Markku Jämsä of Aspocomp. The topic of the presentation was “Thermal Management in PCBs, Options for Designers” and took the delegates on an interesting journey through different methods of PCB cooling, focussing on thermal vias, metal back and embedded copper coin techniques. Jämsä then proceeded to show examples of the technologies before sharing detailed benchmark data of the various options showing advantages and disadvantages of each. The presentation closed with a glimpse of possible future cooling possibilities including mechanically drilled copper filled thermal vias, high conductivity coin materials (>>>500 W/mK), 3D printed complex embedded cooling elements and active cooling.
The last session of the conference “New soldering Technology, Quality assurance and Durability testing” was chaired by EIPC Board Member John Fix of Taiyo America. The first paper entitled “The current state of the Solder Limits” was presented by Crystal VanderPan of UL, US. Vanderpan started with an explanation of the UL PCB Program background and explained that the purpose of the program was to reduce risk. Solder Limits were explained as reflecting the maximum temperatures and times of the assembly soldering process and defined as any component assembly time spent over 100°C or MOT (Maximum Operating Temperature), whichever is greater. It was noted that Solder Limits can be a single time and temperature or multiple times and temperatures (Multiple Solder Limits – MSL) and that solder limits do not apply if hand soldering. Vanderpan went on to explain that Solder Limits are a critical parameter for the PCB and are characterized as part of the recognition process with thermal stress testing used for evaluation of solder limits. The presentation continued with the information that traditional solder float test is not representative of SMT solder operations and that three standard reflow profiles are available to test, namely T230C, T245C and T260C and that collaboration between OEM, assembler and PCB fab continues to find the most appropriate standardized solder limits/assembly profile. Vanderpan summarised saying that solder limits represent the soldering process the PCB is exposed to during component assembly, that the term solder limits can be changed to assembly profile and that PCBs tested with multiple solder limits diminish the risks to end product consumers.
Next the conference to welcomed Robert Boguski of Datest, US, whose paper was entitled “New Developments in Digital Computed Tomography (CT) for Nondestructive Failure Analysis of PCBFs and PCBAs”. Boguski began by contrasting two-dimensional x-ray projection images with two-dimensional vertical-slice computed tomography (CT) images explaining that through CT data reconstruction spatial dimensions of all features can be calculated and digitally rendered into a true volume representation. This representation can then be visualised as the entire volume or an individual sliced view of interest. He further explained that the X-ray penetration information in 3D space is divided into small cube units, voxel pixels, the value of each element being a function of the chemical composition and density of the material in the element; consequently, each small cube is full of features such as defects, boundaries and material properties. Boguski explained Datest’s 225kV microfocus CT setup and showed some very impressive visualisations of objects as diverse as a tangerine, a hard drive and an electric screwdriver. It was of course, however, the detailed visualisation of PCB and PCBA features that most interested and impressed the audience. The presentation concluded with a summary that CT can be a useful inspection technique and that NDT (Non-Destructive Testing) will be integral to the next evolution of manufacturing technologies, in PCB manufacturing as well as many other industries
Dr. Lei Wang of Heraeus Deutschland spoke next on the topic of the Development of a High Reliability No Clean Solder Paste. The presentation began by describing the cleaning of solder paste residues as a complicated and high cost process, the motivation of the development was therefore to find a no-clean solution overcoming traditional concerns of future reliability risk. Wang went on to describe the technical challenge of using an activator to enable wetting whilst not making the assembly susceptible to later SIR (Surface Insulation Resistance) failures explaining that finding the appropriate balance was the key to success. The results of the newly developed DP3 solder paste were presented for a variety of surface finishes and processes, all demonstrating good results. The presentation ended with a summary of reliability, solderability and workability data.
Next the delegates heard from Michiel de Monchy of MacDermid-Alpha whose paper was entitled “Principles of Silver sintering and the importance of PCB finishes”. De Monchy began by explaining the principles of silver sintering, describing it as a process of atomic diffusion whereby at a temperature below the melting point, the atoms in the powder particles diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. The advantages as an alternative to soldering as a die attach were described as superior electrical and thermal conductivity and therefore higher reliability, the demand for which was being fuelled by growth in electromobility – silver was described as the ideal die attach solution. The Alpha® Argomax® – Advanced Bonding Technology Based on Silver Sintering process was then described in detail along with results obtained with a variety of surface finishes. De Monchy concluded with a prediction that silver sintering as a die attach finish to the substrate will grow significantly in the near future.
The last paper of the conference was presented by Hermann Reischer of Polar Instruments, Austria whose presentation was entitled “New automated Controlled Impedance Tester Reischer began with a comprehensive explanation of the need for controlled impedance testing and a detailed description of test methods and procedures. The case for increasing test volumes, tighter tolerances, improved gauge R&R, unattended testing and the elimination of human influence on measurement was then made with reference also to improved traceability. Reischer further explained the design challenges presented with developing an automated test solution and described the development of a rotating differential probe head that was able to adapt to different test coupon formats whilst applying a constant probe pressure. The presentation closed with an impressive visual demonstration of the automated test equipment utilising a custom-built tray containing 30 test coupons.
After the closing panel discussion I brought the conference to a close commenting on how delighted I was as a metallurgist to have had so much high quality content in my field of expertise. I thanked the sponsors, with a special mention of Elga Europe for their kind hospitality, the session chairs, the speakers and EIPC Technical Director Tarja Rapala and the programme team for their excellent and valuable contributions to the conference. Sincere thanks were also given to EIPC Executive Director Kirsten Smit-Westenberg and EIPC Project Manager Carol Pelzers for their diligent and detailed attention to detail ensuring our continued success. I noted that our much-loved reporter and journalist Pete Starkey was “hors de combat” after a fall earlier in the week and wished him well for a speedy and full recovery. In closing I invited the delegates to join us for the next EIPC conference to be held in Leoben, Austria June 13 & 14 which will include a factory visit to AT&S.
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