THERMAL MANAGEMENT Trace Current/Temperature Relationships Remember the current carrying capacity charts in IPC-D-275? Those charts that were impossible to read without an eye loupe, and of questionable validity to boot? It’s long past time that designers had a clear, comprehensive understanding of why traces heat up with current. A look at the basic physics, plus an explanation and evaluation of the current carrying chart data from the IPC standards. When optimizing board area to take into account thermal effects, thermal simulation tools appear the best way to go. by Douglas G. Brooks, Ph.D. and Johannes Adam, Ph.D.
PCB DESIGN Rigid-Flex PCB Design for an Innovative Helmet-Mounted Display To create a prototype binocular holographic waveguide visor display, an Air Force pilot, a cutting-edge high-speed design and HDI boards were used to significantly decrease cost, volume and weight of the traditional helmet-mounted displays. by Dr. Dave Cowl
QUALITY CONTROL PCB Fabrication Processes and their Effects on Fine Copper Barrel Cracks A preliminary survey of PCBs that failed thermal shock qualification showed a cracking incidence rate of approximately 15% across multiple suppliers. These results led the investigators to question that if cracks were present, under what manufacturing conditions could the cracks be mitigated or eliminated. by Edward Arthur, Charles Busa, Melissa Durfee, Chad Gibson and Wade Goldman
EMS TOP 50 EMS in Overdrive The absence of major changes to the annual list of the world’s largest contract assemblers should not obscure a few definitive trends behind the scenes, namely automotive and Apple. by Mike Buetow
IPC APEX RECAP Going Vertical The annual IPC trade show was bigger and more built up than ever, which had the (unintended) net effect of making attendance look like it was down. Still, the show had its share of innovations – albeit primarily on the assembly side – that made the trip to San Diego worthwhile. by Mike Buetow
CONFORMAL COATINGS IPC-CC-830B vs. the ‘Real World’ A variety of commercially available, internationally qualified conformal coatings were applied in varying thicknesses to SIR coupons by dip, spray and selective-spray, then subjected to thermal shock. The results demonstrated that the flat FR-4 test board used for IPC-CC-830 qualification does not adequately stress conformal coatings during thermal shock testing, leaving open the question whether the standard is sufficient for simulating actual use environments. by Carolyn Taylor and Phil Kinner
QUALITY CONTROL Color for PCB Control Some colors are so standardized that changing them serves no purpose and could indeed be counterproductive or even dangerous. Likewise, printed circuit boards are always green – except when they are not. by Robert Sergio Simon
CAD PREDICTIONS #1 The Design Tool Challenge: More Functionality, but Easier to Use Board designers want tools that enable sophisticated analysis and features like MCAD-ECAD and rigid-flex but without requiring an advanced degree to use them. by Hemant Shah
CAD PREDICTIONS #2 The 3 Challenges Facing the Future of PCB Design Changing demographics is driving demand for system-oriented tools. What we can also expect in the short-term are tools that accommodate more "part-time" users as the number of dedicated PCB designers declines. by David Wiens
CAD PREDICTIONS #3 Breaking the Silos Architectural validation and modular design are driving designers to more product- and team-centric approaches. by Bob Potock
RESIDUES How Clean is Clean Enough? A test matrix investigated 12 ionic contaminants in five concentrations to assess the electrical response under controlled heat and humidity conditions. The study used the limits per J-STD-001 for surface insulation resistance. The tests determined at what level of contamination and spacing the ionic/organic residue has a failing effect on surface insulation resistance. by Terry Munson, Paco Solis, Nick Munson, Steve Ring and Evan Briscoe
COMPONENT SELECTION 01005: Size Does Matter Designing PCBs with 01005 components involves tighter constraints in regard to component spacing, layout, and other related considerations, as well as access to higher levels of automation at assembly. by Arbel Nissan
FLEX DESIGN Designing Flex Circuits for Wearable Electronics The human body has very few flat, rigid surfaces, and standard PCBs don’t easily conform to its various contours. This is where flexible circuitry really shines. But while flex circuits are able to conform to the many twists and turns of a human body, they still have limitations. by Mark Finstad
PACKAGING Cost/Benefit Tradeoffs of Capacitor Part Size vs. Manufacturing Efficiency Passives continue to eat up 70% of the board area. How smaller part sizes require less solder and can eliminate parasitic inductance. by Chris Reynolds
COMPONENT PROCESSING Embedded Passive Technology Materials, Design and Process EPT can simplify assembly and test processes and reduce the actual cost, especially when using 0201 packages or lead-free processes. A summary of resistor material selection, evaluations and duplication of a complex digital design. by Hikmat Chammas
