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This article is an update of the Holden-Carano article originally published in the February 2013 issue of The PCB Magazine.
One of the most difficult printed circuit boards to adapt to Pb-free assembly processes is the high-layer count multilayer. Often, these multilayers have through-hole and hand-soldered components, and requirements for two or more rework cycles. The higher reflow temperatures and slower wetting of lead-free solders place an enormous strain on the laminate and copper-plated hole barrel. In many cases, the boards cannot be assembled reliably even with newer, higher thermal performance FR-4s.
One solution to this problem is to redesign the multilayer using current design rules and newer innovative fabrication technologies. This article will review four of these new and enabling technologies:
- Laser-drilled microvias;
- Routing BGA using channels;
- Contribution of new SMT connectors; and
- Layer assignment changes (architectures).
Microvias offer the most significant opportunity to reduce not only the layers and thicknesses of multilayers, but also their cost while improving their electrical performance and density. Several examples will illustrate these new opportunities. Since blind vias are surface phenomena, to get the maximum benefit from them, layer assignment for signal, ground and power need to be reviewed and alternative constructions considered. These blind vias, by reducing the number of through-holes, contribute to increase routing density that allows the lower layer usage. Finally, by replacing through-hole connectors with surface mount connectors, higher connector density and improved electrical performance can be realized.
The resulting new multilayers are not only thinner, cheaper, and easier to design, but are less costly and suitable for lead-free assembly.
Read the full article here.
Editor's Note: This article originally appeared in the April 2014 issue of The PCB Magazine.
Nolan Johnson, I-Connect007
Nolan Johnson hears from Alun Morgan, Technology Ambassador at Ventec, and Mark Goodwin, Ventec’s COO, about the benefits and risks posed by new PCB-oriented legislation in the U.S. and Europe. Faced with a rapidly consolidating industry, especially in the face of mounting pressure from the Russia-fueled energy crisis, government intervention is a welcome prospect—as long as legislators are committed to addressing the full scope of the issue, including the supply chain’s migration to Asia. Ventec is hopeful that, having been called on to educate government officials on the challenges facing the industry, they will help spur future legislative changes that will protect and grow the industry’s interests.
Pete Starkey, I-Connect007
Pete Starkey stops by the Aismalibar booth at electronica to hear from Uwe Lemke about the company’s plans to further expand its footprint in the Chinese PCB market and how evolving e-mobility constraints have propelled a growing demand for materials that can address electrical isolation and thermal conductivity concerns in high voltage battery systems. As always, Aismalibar is up to the task, having developed a new thin fluid coating technology that boosts the performance and reliability of any interface using the same foil-based technology that has long defined its impressive line of product offerings.
Pete Starkey, I-Connect007
Regardless of the potential distraction of the international football match between England and Wales in the World Cup competition, an enthusiastic crowd of PCB fans gathered in Meriden UK for the Institute of Circuit Technology Christmas Seminar, an eagerly-awaited networking opportunity that included a face-to-face industry welcome event and an outstanding technical programme. Guest speakers highlighted new technology in selective solder nozzles, flexible circuits, industry cooperation, and a greener future by recycling PCBs.