FLEX CIRCUIT DESIGN Ensuring First-Time Success in Rigid-Flex PCB Layout For designers of products such as wearables, where every cubic millimeter of space within the enclosure is used, and two or more PCBs must be folded into place in final assembly, flex is becoming a popular choice for more than just a replacement for cable. One flex section can replace a cable plus two connectors, offering cost savings on top of the space benefits. by Robert Huxel
HIGH-SPEED DESIGN Designing PCBs for DDR Busses The DDR bus is one of the widest commercial high-speed busses, if not the widest. Designing the bus comes with a set of challenges that can be intimidating to designers new to the bus. In the first of a series on DDR, the author looks at bus concept basics. by Nitin Bhagwath
ZIW RECAP Zuken Conference Transforms PCB Design Landscape End-to-end design takes center stage at Zuken’s annual users conference. by Chelsey Drysdale
BASE MATERIALS Avoiding Self-Limitation in PCB Materials Specification Designers tend to focus on electrical performance of base materials, while the fabricator must somehow make it work. Could understanding the full scope of the tradeoffs unchain users from basing decisions on dielectric performance alone? by Roy Akber
STRIPLINE MODELING Electrical and Design Parameters Optimization of Transmission Lines in Computer Systems Computer system designers currently use a host of international standards, GOST 21552-84 Computer Equipment, International Electrotechnical Commission (IEC) publications, as well as their own guidelines for developing specific types of computer equipment employed for the analysis and synthesis of transmission line parameter control. Here, an approach is described for using the simulation tools to improve data exchange reliability through the use of the transmission lines, including on multilayer printed circuit boards. by S.A. Sorokin and S.M. Chudinov, Ph.D.
EMS TOP 50 Blurred Lines Another year, another Foxconn display of utter dominance in contract manufacturing. But in what was in many respects a relatively quiet year, there was much more happening under the radar. A look back at the major trends of 2015, including the race to India by the world’s largest EMS/ODM companies. by Mike Buetow
PCB INSPECTION Industrial CT (X-Ray) Scanning: A Substitute for Microsectioning? The problems with microsections are legion, starting with the fact they are destructive, and represent a point along a trace that might not be representative of other points along the trace. Could x-ray have value for measuring trace parameters? by Douglas G. Brooks, Ph.D.
APEX EXPO RECAP Shop Talk At IPC Apex Expo in March, the introduction of a shop floor communications specification was the talk of the annual trade show, overshadowing – and not by a little – the relative paucity of new equipment and materials making their worldwide debuts. by Mike Buetow and Chelsey Drysdale
FACTORY MANAGEMENT Energy Reduction in the Electronics Facility Most electronics manufacturing factories have many opportunities when trying to reduce energy use. Moreover, certain capital improvements have short returns on investment and meet the overall goal of reducing energy consumption and lowering operating costs. by Scott Mazur
PI-DC ANALYSIS DC Analysis of PDN: Essential for the Digital Designer DC analysis of a power delivery network, commonly referred to as IR drop, DC power integrity, or PI-DC, answers fundamental questions that every digital (or analog) designer should have. Optimizing the PDN can save precious design real estate and layers, resulting in lower cost with increased performance and reliability. by Jeff Loyer
BTC DESIGN Via-in-Pad Design Considerations for Bottom Terminated Components on Printed Circuit Board Assemblies With their small component body footprint and minimal PCB area requirements, physical designers are keen to incorporate small footprint QFNs to meet a variety of voltage/power regulation, logic controller and clocking needs. Methods for filled thermal via design points to ensure a planar surface upon which to solder the component to the thermal pad – including solder mask via tenting, encroached vias, and via-in-pad plated over – bring manufacturability trade-offs, reliability, and cost impacts. A new alternative using QFNs with open thermal via-in-pad (VIP) structures uses conventional PCB through-hole via technology that is not plugged nor filled in any manner, ensures proper via sizes/pitch/counts/locations are achieved, and incorporates custom solder mask window patterns overtop copper thermal pad areas. by Matt Kelly, Mark Jeanson and Mitch Ferrill
THERMAL MODELING Empirical Confirmation of Via Temperatures Current doesn’t determine the temperature of a via; rather, it is the temperature of the associated traces. If the traces are sized correctly for the current level, much smaller and fewer vias are required to transition between trace layers than has been previously believed. In practical terms, designers can have much greater flexibility in freeing routing channels underneath the traces on their boards. by Douglas Brooks
SIGNAL INTEGRITY Insertion Loss Modeling Lessons from a study that attempted to correlate measured insertion loss to that modeled with an Intel-proprietary 2D modeler and a commercially available tool using a collection of coupons representing a range of materials and vendors. by Jeff Loyer
THERMAL OVERLOAD Empirical Results of Fusing Tests Trace thermal overload situations can be grouped into two broad categories. But even slight current overloads result in unpredictably long fusing times – sometimes hours. by Douglas G. Brooks, Ph.D.
SMT ASSEMBLY Creative Technological Solutions for Complex PCBs What the optimal assembly solution for a 2-mil-thick flexible PCB is, and other mysteries. by Arbel Nissan
SHOW RECAP Machines in Munich The biennial Productronica trade show – the industry’s largest outside Japan – was filled with new machines, if not necessarily new technologies. by Mike Buetow
