EIPC Summer Conference 2019, Day 1

Estimated reading time: 14 minutes

The first part of the session concluded with a paper prepared by Frank van den Bosch of Ucamco, which was presented by André Bodegom of Adeon Technologies BV. The presentation covered direct imaging (DI) applications and began with a look at the development of DI technology from 2005 to the present day. Bodegom described the features of the Ledia 6 System, which utilises a broad multi-wavelength optical system ranging from 350–440 nm to diffuse the energy optimally throughout the resist or solder mask.

The Ledia 6 System allows users to finetune each wavelength’s power individually for optimal results on or each material. Examples of the results were shown with 50-µm solder mask dams without undercut. Bodegom described further details of the autofocus, image-head calibration, and alignment system for registration accuracy. Next, he explained Ledia’s Dynamic Process Format (DPF) Interface for Serialization and Image Stamping (DISI) System for generating on-the-fly board serialization and variable image stamps at the time of exposure as a method to ensure unique PCB identification and traceability. The presentation closed with an overview of automation options for inner and outer layers and solder mask.

After a short coffee break, the session continued with Jan Pedersen of Elmatica presenting on how a broker’s communication can solve technical issues. He started with an overview of Elmatica from its founding in 1971 to its position today as a digital supply chain partner. Pedersen displayed a chart mapping required knowledge of processes and technologies, showing the positioning of the customer and two example PCB factories where the broker was able to bridge the technical knowledge of the PCB factories whilst exceeding the process knowledge of the customer. Through three case studies, he demonstrated how communication and process knowledge solved the issues of via opens and bow and twist and offered a depth-milled semi-flex solution. I was delighted and proud to have been named as the person who suggested the depth-milling solution to Elmatica! Pedersen closed with words from one customer: “With your involvement, we always find a solution and end up with delivery.”

Next, we heard from EIPC Vice President Emma Hudson of Gen3 Systems who delivered her paper “Ionic Contamination: So, What Has Changed?” She explained why we should care about ionic contamination and described the pros and cons of common ionic contamination test methods. Then, Hudson addressed how the introduction of IPC J-STD-001G Amendment 1 had replaced the 1.56 μg/cm² of NaCl equivalency requirement, which was established in the 1970s, with an objective evidence requirement to qualify that the contamination left on the PCBA is acceptable and monitor that qualified contamination levels are not exceeded during production. So far, so good.

However, Hudson then pointed out that other IPC requirements, such as the IPC-6012 Automotive Addendum, still include a 1.56 μg/cm² of NaCl equivalence before solder mask application. The IPC-6012DA-WAM1 Automotive Applications Addendum to IPC-6012D also has a 0.75 μg/cm² of NaCl equivalence before solder mask application with no scientific justification for the number selected—just that it’s “better” than 1.56 μg/cm². Despite the inconsistencies arising, Hudson argued the merits of the new approach and described the process by which objective evidence is obtained before concluding that PCB manufacturers should expect to start hearing more about this from their customers as the changes come down the supply chain.

The last paper of the session, “From PCB to Assembly: Performance of New Coatings Applied Along the Production Chain,” was delivered by Sven Kramer of Peters. Following an introduction to the Peters Group, Kramer focussed on liquid photoimageable solder mask (LPISM), coatings supporting effective thermal management, and protective/conformal coatings for enhancing reliability and lifespan. He showed that the application methods of LPISM have regional differences leading to challenges in compliance with a specified maximum thickness on the top of tracks and a specified minimum thickness at the track corners.

Then, Kramer showed a combination of a printed heatsink and a printed thermal interface paste were used to level surface roughness, displace air, and thereby create an optimum connection to the cooling element to support heat transfer and heat dissipation from the assembly side to the cooling side. He also covered conformal coatings which are used to enhance reliability and lifespan.

Further, Kramer showed differences between micro-encapsulation and conformal-film/coat, along with various stress factors affecting electronic assemblies. He ended with the message that successfully working in the field of high-end coatings for electronics requires considerably more effort and investment in technology than ever before.

Afternoon Sessions

After lunch, EIPC Board Member Michele Stampanoni of Cicor Group introduced the next session on “New Material and Coating Technologies.” Steve Woods of Sun Chemical presented the first paper of the session and covered developments in advanced LPISM for high-temperature and DI applications. He also described the development of a solder mask designed to meet the higher temperature thermal cycling tests for the automotive industry.

The development process utilised variants of existing resin technology whilst maintaining pigment levels/colour density of standard solder mask in producing a product that could be applied by screen print, curtain coat, and spray methods and that was suitable for exposure on DI and conventional exposure light sources. The thermal cycling requirements of two automotive Tier 1 suppliers were described and the test results of the most stringent of these being 2,000 cycles of a 15-minute dwell time. In addition, Woods demonstrated that the product developed was able to meet the requirement without failures (40°C to +170°C). He continued by showing positive test results for moisture and insulation resistance and electrochemical corrosion as well. His final remarks emphasised that laminate selection and ink film thickness control were critical for success.

Frank Louwet of Agfa-Gevaert took the podium next to present his paper “Be Flexible, Go Digital: Deeper Insights into the Benefits of Inkjet Solder Mask for PCB Production.” After an introduction to Agfa-Gevaert, he charted the development of ink application technologies from screen printing to laser DI and additive inkjet printing. Louwet emphasised the importance of 100% additive and digital technologies with the key benefits of printing solder mask only where necessary leading to cost-efficient solder mask deposition, no solder mask in vias, prevention of solder bridges between closely spaced solder pads (dam printing), resistance against electrical breakdown, and solder mask thickness.

Louwet also demonstrated the reduction in process steps by using inkjet for solder mask application and the significant reduction in the process ecological footprint compared to conventional technologies. He described how variable thickness, coverage and jetting performances, and surface quality are achieved before detailing the physical and electrical requirements. Louwet concluded with a summary of inkjet benefits, including solder mask being applied in the amount needed only on the desired areas and the high reliability and excellent jetting performance while meeting today’s demanding PCB requirements.

Staying with the inkjet printing theme, but this time from the equipment side, the next speaker was Joost Valeton of Meyer Burger NV. First, he introduced Meyer Burger as a leading global technology company specializing in innovative systems and processes. Valeton showed the various industries where inkjet systems are used before focusing on PCB technologies and the benefits of being environmentally friendly by reducing process steps along with waste and material usage.

Valeton then described the equipment solutions offered by Meyer Burger and explained that the key features of software integration and small drop size from the printheads (2.5 pL) plus drop flow-out compensation and advanced resolution control for accurate feature size produced the highest quality solder mask printing. He showed visual examples contrasting performance with other systems. Valeton ended with the technical details that 50-μm line/space features are achievable and that experience shows a >96% availability and printing of up to 60 sides/hour.

Page 2 of 3

• < Previous Page
• Next Page >