PCB Technical Publications
Product Development Efficiency Through ECAD-MCAD Collaboration
Collaboration between mechanical designers (using MCAD tools) and PCB designers (using ECAD tools) is becoming a priority for many product development teams. Allowing the PCB designer and mechanical designers to view layouts, suggest and approve/reject changes, and view this information on their own tool is a large step forward in advancing this collaboration, with the ultimate goals being shorter design time with fewer re-spins. And, that makes for a healthy bottom line.
Distributed Autorouting Using XtremeAR
Learn about XtremeAR process flow for faster autorouting of PCBs by connecting multiple workstations working together, real-time, on the same design. This process can be used as the ultimate team design environment. Faster results can lead design teams to try different routing options to find the optimum route strategy. This paper covers system setup, the required environmental variables and the necessary licenses to start the XtremeAR session. It also describes the strategies for session controls through the XtremeAR client Manager, XtremeAR recording/playback & the performance analysis for XtremeAR session.
TeamPCB: The Next Paradigm Change Begins
Everyone in the electronics industry is looking for ways to increase productivity, reduce costs and shorten time-to-market. Processes have been reviewed and tweaked over and over, and serial methods of round-the-clock and round-the-world design of large boards has become popular again. Since PCB software vendors heralded design reuse and variants tools in the early-to-mid 1990's breakthrough methodology adjustments or paradigm changes that can enable dramatic productivity improvements have not been unveiled. It seems as if just keeping up with new manufacturing technology and high-speed requirements has kept EDA vendors fully occupied-until now. The Systems Design Division of Mentor Graphics delivers TeamPCB and a series of other new products this year.
TeamPCB is available as an add-on option for Board Station and Expedition PCB , running on Windows and Unix platforms.
Simultaneous Design Technology: A Revolution
New software technology has been developed that enables effective parallel design of a circuit board. This technology enables multiple designers, processes and heterogeneous tools to work on the same design database simultaneously and achieve significant gains in design productivity. But, unlike classical divide - and conquer methods that break down a design into pieces and operate on them independently, this new technology enables concurrent progress on a common database, automatically synchronizing changes and resolving conflicts - a first in the EDA industry. This paper focuses on the methods and applications of new parallel design technology that offers a novel paradigm for circuit board design. Topics include:
- Review of design problems and concurrent methods
- Parallel design architecture
Applying the parallel design technology to:
- Layout
- Autorouting
- Circuit and Board Design
- System Design
Propagation Times and Critical Length: How They Interrelate
Signal propagation speed is directly related to the relative dielectric coefficient of the material(s) surrounding the signal trace. Traces are considered short, from a reflection standpoint, if the signal can travel to the end of the trace and return to the driver in a time period shorter than the rise time of the signal. Long traces are those where the round trip propagation time is longer than the rise time. In our industry, the critical length, the length where we need to consider using transmission line design and termination techniques, is generally considered to be the length where the round trip propagation time of the trace equals the rise time of the signal.
High-Speed Design: The Benefits of Analysis-Driven Routing
"Analysis-driven routing helps you create more robust designs by optimizing layout …which ultimately speeds your time to market."
Most printed circuit board (PCB) designers do not like the aesthetic results of an autorouter and believe that if they were given enough time they could do a better job themselves. However, today’s complex designs and reduced cycle type demand the use of automation wherever possible. New industry developments require the engineering team to make use of true, multifaced, analysis-driven system design in order to compete in a constantly changing environment. This paper provides a brief history of high-speed routing, and demonstrates why traditional and constraint-driven routing systems are too time-consuming for today’s fast-paced design life cycles. Issues arising from delay and crosstalk routing, placement and termination impacts, differential pairs, and decoupling capacitor breakout routing are discussed. Physical and electrical views are provided to illustrate the numerous examples.
Optimizing Test Coverage - Recommended Design Rules for an X-ray and In-circuit Test Strategy
Today's complex and high node count printed circuit (PC) boards can be difficult to test. To accurately detect, diagnose and repair their manufacturing faults, several manufacturers test these PC boards with multiple types of test systems. This multiple test style environment combines two or more different types of PC board testers. Currently one strategy combines automatic x-ray inspection with a modification of traditional in-circuit testing.
This strategy changes the test department's overall test paradigm, and has significant impacts on design for testability guidelines for these complex, high node count PC boards. New guidelines need to be established to ensure efficient testing of PC boards with automatic x-ray systems, while also preserving in-circuit requirements that persist. These design guidelines can also assist in providing for selective access removal in cases where automatic x-ray systems provide efficient testing capability.
This paper proposes, examines and summarizes new design for testability guidelines for a combined x-ray/in-circuit testing environment. The paper reviews and updates rules to help test and design engineers provide high-yield processes for x-ray inspection and in-circuit test of PC boards. It also presents guidelines which take advantage of this combined test strategy to reduce required in-circuit probing accessibility, redundancy of test across test systems, and maximizing test efficiency while lowering per unit cost of test.
HDI's Beneficial Influence on High-Frequency Signal Integrity: Part 1
Microvias or High-Density Interconnect (HDI) printed circuits are now being designed in ever increasing quantities. HDI brings some interesting new solutions to age-old signal integrity (SI) and density concerns, and concerns that will grow as rise-times continue to drop.
This article focuses on four major areas of SI concerns: 1) Noise (including Noise-reflections, Noise-crosstalk, and Noise-simultaneous switching), 2) Electro-Magnetic Interference (EMI), 3) Interconnect Delays and 4) Decoupling.
In each case, HDI offers improvements and alternatives, but it is not a panacea. A couple of 'cautions are listed that can be a major obstacle to HDI implementation; fortunately, these caveats are not SI-based. Important to SI are the materials used in HDI. Although not the focus of this article, the selected materials, the dimensional stack-up, and the PCB design rules will influence SI and electrical performance (impedance, crosstalk and signal conditioning). Miniaturization provided by HDI will be a major contributor to SI performance.
In PART 2 of this article, the HDI wiring of three fine pitch BGAs and CSP are highlighted. These are typical of the growing use of fine-pitch components. The three are: 1) 676 I/O, 1.00 mm pitch BGA, 2) 384 I/O, 0.8 mm pitch BGA and 3) 218 I/O, 0.65 mm pitch microBGA.
Finally, the SI example is also a case study in cost reduction. The 'before' and 'after' conditions are reviewed to emphasize the cost reduction and "time-to-market" advantages of HDI technology.
The Developing Technologies of Integrated Optical Waveguides in Printed Circuits
High Density Interconnect (HDI) printed circuits are now being designed in ever-increasing quantities for very high speed applications. The challenge of opto-electronics and integration of photonics into the printed circuit has started to take off. In the next seven years, expectations are that photonic PCBs will grow to a $2.5 billion industry.
This paper looks at the issues, materials and current processes being researched to create this integrated Opto-Electronic Circuit Board by European, Japanese and North American organizations. In addition to reviewing the global players in polymer photonics, this paper will review the current programs of three of the six groups globally:
- EOBC-OptoFoil (Univ. of Ulm, Fraunhafer Inst, Daimler-Chrysler, Siemens)
- NTT
- PolyGuide (Dupont, HP)
- University of Texas
- TOPCat (NIST, 3M, Goodyear)
- JIEP
How to Get Started in HDI with Microvias
Electronics continue to become denser, smaller and more complex. The drive to produce more hand-held applications is obvious, but "Mother Nature" is playing a big role in determining the other drivers. As chip signal rise-times continue to decrease (due to smaller gate geometries) the resulting signals are more susceptible to interconnect parasitics. Signal Integrity (SI) improves with miniaturization. All these smaller size factors are drivers for HDI with microvias.
Integrated Circuit increases in total gates has required more pins, as well as finer pin pitch. Over 2000 pins on a 1.0 mm pitch BGA is not unusual, as is 296 pins on a 0.65 mm pitch device. The faster rise-times, as well as the need for SI, require an increasing number of power and ground pins. Consequently, this drives the need for more layers in multilayers. Again, this drives the need for HDI with microvias.
This paper goes over the STEPS in deciding if you need HDI-microvias and how to START. Included is HDI Standards, design trade-offs, materials selection, fabricator selection and Benchmarking, test vehicles, HDI reliability, electrical performance, and CAD features for HDI.