PCB007 Magazine

PCB-May2018

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48 PCB007 MAGAZINE I MAY 2018 it Surface Contamination Testing because we are not really talking about cleanliness, but to control contamination levels of the solderable surface. The smaller the solderable pads we have, the more we need to control the contam- ination level. And with increased variations in complexity and miniaturization, we may need product-related acceptability levels instead of a rigid standard level for all technologies. This is a hot topic where the industry is in a need of an urgent development. While waiting for a better solution, my automotive addendum group have found a compromise that combines current test methods in a way that gives im - proved reliability and better control. We also see a development of new methods using non- solvent solutions that we believe will improve contamination testing in the near future. Moisture Sensitivity Levels (MSL) for PCB One direction of the velocity of PCB technol- ogy is increased complexity and density. With this increased complexity of the PCB, con- trolled humidity inside the boards is vital to avoid delamination and product failure. How do we control the moisture level inside the PCB and for how long can the PCB be kept in the assembly shop floor environment before the moisture level becomes a problem? Certainly, this depends on the base material's moisture absorption rate, and some materials like poly- imides do absorb moisture at a rate that re- quires control. Moisture sensitivity levels have been in use for components a long time, as described in J- STD001 but not for the PCB. Based on Elmatica´s internal MSL recommendation, I suggested at the 2017 IPC meeting and followed up this year with the result that the committee developing IPC-1601 will further develop and implement to the next revision of the standard. I believe this will be a valuable guide for users of PCBs with high moisture absorption levels. Specifications—More Important Than Ever Hand in hand with changes in the technolo- gy we must have precise specifications. Anoth- er unpaid job of mine (but a true pleasure and very exciting) is to chair CircuitData. The other day, I received a PCB specification requiring me to follow IPC-610 Class 3, and with only fractions of a sufficient PCB specification. So, a time-consuming communication began. Hopefully, we will be able to deliver what the customer needs, but insufficient specifications make the process longer and more difficult. To succeed with increased PCB options and complexity, a detailed and correct PCB specifi- cation is a must. The future is a digital specifi- cation file such as the open source CircuitData file in combination with an intelligent produc- tion file such as IPC-2581. Such files give much more information than the good old Gerber. The Future We cannot talk about the velocity of PCB technology without mentioning 3D printed cir- cuits. I am following this from the sideline. 3D circuits including components will surely one day be a disruptive technology to the standard PCB, as we know it today with components soldered. That will be a new ballgame! Even 3D circuits in the early stage of their life cycle, with the current PCB technology as I see it, will in the near future keep on following the same track towards miniaturization. What I call micro PCBs are today touching BGA sub- strate manufacturing and we need a term and a set of typical features that describes this group. I also believe we will see an increased level of embedded technologies and complexity of mixed materials that will again challenge orga- nizations like IPC to be up front with the de- velopment of standards. The changes we have seen over the last 10−15 years, unfortunately, have not been reflected by the standards at the same rate. The only way to improve the pro- cess of developing standards that meet the ve- locity of PCB technology is to participate. Don't let the technology outrun you. Join in and take part in the exciting future of printed circuits. PCB007 Jan Pedersen is senior technical advisor with Elmatica.

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