Review Materials Enabled Designs: The Materials Engineering Perspective to Product Design and Manufacturing

Most of electronics assembly is achieved in non-mechanical bonding processes: lamination, plating, soldering, underfill, encapsulation, and so on. Even mechanical joining — such as board-to-board connectors — is based in one or more material-based interconnect. I promised a review of a materials-focused text in the blog post, New Materials for an Evolving Industry, and Michael Pfeifer's text delivers the well-rounded, prototype-to-production viewpoint of materials usage we were looking for.

Pfeifer’s new text book, Materials Enabled Designs: The Materials Engineering Perspective to Product Design and Manufacturing, published by Butterworth-Heinemann, an imprint of Elsevier, covers design, materials, manufacturing processes, reliability, quality and process control, yield, and cost management with materials as the focus. Engineers should “better understand the risks and rewards associated with…materials used in a product; the manufacturing processes used to produce the product; and the suppliers of materials, components, and subassemblies used in a product,” Pfeifer asserts.

The book also has sections focused on total product design practices and smart operating procedures, which requires most companies to specify components without strict controls over all materials used. Pfeifer offers these tips:
“Start with materials that offer a high probability of success. Do not consider the entire world of materials, components, and subassemblies for use in a product. Work out all details of a strategic custom component or subassembly before using a low-cost supplier. Consolidate materials within and across product platforms. Develop design guidelines. Include a budget for materials engineering support.”

Flow charts and matrices throughout the chapters are visual prompts to readers, asking them to consider product design with discipline and constructive creativity.

While a large portion of the text is devoted to material properties and materials science, the theme throughout is about perspective. The reader should emerge with a stronger background in properties of solders, surface finishes, etc., and — more importantly — with a concept of the role materials play in a product’s success, from design to sourcing to manufacturing and test. As Pfeifer states, poor understanding of materials science can lead to “delayed product launch, field failures, poor customer satisfaction, and poor sales.” He encourages “understanding the relationship between the properties of a material, its compositions, its microscopic structures, and how it was processed.” For example, a high-volume assembly may be dense and small with high computing power, but if the solder specified is easily degraded by the print process, frequent downtime at the printer will kill expected yields. Materials ignorance can be costly.

The text is available from Elsevier. Pfeifer is president of Industrial Metallurgists LLC. He wrote the book based on materials compiled for a Manufacturing and Design Engineering (MaDE) program course at Northwestern University.

Meredith Courtemanche, managing editor

PCB Design for Manufacturing: Soup to Nuts

Sunstone Circuits and National Instruments announced a collaboration this week, with National Instruments joining Sunstone’s “ECOsystem design environment” for PCB design. Sunstone is aiming for a design approach that brings customers from disparate CAD files, mechanical layouts, bills of materials (BOMs), and the like into one sleek supply chain that integrates module design, parts ordering, physical planning, and more.

National Instruments adds a new gear to the machine. Customers using NI Multisim and NI Ultiboard can order prototype PCBs via the Sunstone ECOsystem, and Sunstone is hoping more off-the-shelf hardware providers will follow suit. Electronics assemblers are stretched to the limit for resources and resource management, Terry Heilman, president and CEO of Sunstone, explained, and automating the process, eliminating human error and time-wasting activities, is the way to bring PCB design and prototyping into manageable and valuable work schedules. The full news story about National and Sunstone’s collaboration is available on smtonline.com.

Small design problems snowball, classically, causing massive problems at the manufacturing stage. Design for manufacture (DfM) is one of the most important tools prototype/new product designers can use to stay on time and on budget. Consider a disconnect between mechanical and electrical design. At the design phase, with DfM, component height tolerances are established and the finished assembly fits properly in its case when manufactured. Without DfM, one component may be too tall for the PCB’s case, for example. A new component must be substituted, BOMs changed, new parts ordered, etc.

By adding National Instruments to the ECOsystem, Sunstone is amassing companies that specialize in certain areas — National for PCB assemblies, Digi-Key for component sourcing, Screaming Circuits for PCB build — and properly networking them to serve the electronics designer and manufacturer most efficiently and transparently. Fewer people and less time, less waste, lower investment are all goals for the ECOsystem users.

Recently, I was part of a team that launched SMT’s newest sister publication, PVWorld. We launched the Website on schedule, not without any bumps and baubles and retracing our steps. The element that kept work flowing was a close interaction with the website designers, content managers, and other online gurus that instructed us and knew how to resolve every issue that came up. Can it work? Can the new product introduction (NPI) supply chain progress smoothly like a well-oiled machine? It may not happen every time — certain parts are not available through certain distributors, last-minute changes from above may push designers back a step or two, freak snowstorms may hold up a delivery truck on its way to the EMS provider — some wrenches in the gears cannot be helped. But the ECOsystem concept represents an ideal that Sunstone is pushed toward achieving, adding partners at a fast clip, including the most recent National. The ECOsystem works like a consortium product, with all companies contributing toward the goal of DfM.

Meredith Courtemanche, managing editor

PCB Designers Wielding Power

PCB design doesn’t occur on the SMT assembly line, but good design is the foundation of every process step, from proper screen printing to optimized pick-and-place. With a good design, not only is the board easy to test, it also passes those tests. This week, Mentor Graphics released HyperLynx PI, a design software program aimed at improving power integrity on the PCB. Power has become a major issue, due to environmental concerns with power sapping, due to device heat and operating time challenges with the rise of mobile devices, due to miniaturization, densification, the list goes on. Noise, voltage drop along traces, current density variation, and other problems occur. John Isaac, Systems Design Division, Mentor Graphics, gives the example of 5-V components. In the past, all ICs on a given PCB ran at 5 V. Today, with densification, higher performance, and miniaturization, a board with all 5-V ICs would be disastrous. Some use 1.2 V, even 0.9 V, and multiple ICs on a board will have multiple power requirements. With all 5-V components, 0.3 V of noise is no issue. Change to 1.2 V, and suddenly 0.3-V noise is disrupting operation. If each power net had its own layer in the circuit board, the result would be a Stone Age design, thick and cumbersome. To keep our devices power-sipping, remote, handheld, economical, etc., PCB designers need to optimize power nets.

When a board has several voltage requirements and a limited layer stack, power nets will be “jigsawed” together on shared planes. “PCB designers can be slammed with more than 30 power distribution networks, requiring split power planes, networks arranged like jigsaw puzzle pieces, and still the requirement to keep nets around their respective ICs and connected to the power inputs,” Isaac explained. The HyperLynx PI tool was created for designers to evaluate and mesh these power requirements, reducing the need for decoupling capacitators, shortening design times and eliminating respins, and improving signal integrity.

HyperLynx PI post-route DC drop: a view of the voltage plane highlighted in the board viewer, along with the results (color map) of the DC voltage drop along that plane.

Two common problems can be discovered and resolved with power integrity analysis: DC voltage drop and current density issues. The HyperLynx PI tool illustrates power distribution networks in such a way that either of these design setbacks is easily found and dealt with. For DC voltage drop, ICs placed a certain distance from the power source are not getting their required voltage. Voltage planes are irregular and full of holes, Isaac notes, and a 1.3 V power source on the bottom left side of the PCB, for example, might go through a 1.2 V power distribution network and lose enough current to fall below the tolerances (typically ±10% for the 1.2-V IC on the right side of the board. The under-voltage condition can cause a variety of IC errors from bit errors to complete failure. Designers can use HyperLynx PI’s color-key map of the board to determine where too little power is getting through, and adjust the bill of materials (BOM), PCB layout, or other elements to improve the design.

HyperLynx 3D current density plot: a 3D plot of the current density on a plane. Areas of high current density can lead to board damage, disconnected power, and possibly fires.

With current density problems, bottlenecks and hot spots are created by concentrating the flow of power too much in one area of the board. When ICs switch or perform various functions, they create a huge current draw, exposing these density problems. Noise and resonance are created by the current, disrupting optimal operation. Designers might solve this through AC analysis, which leads to layout changes, dropping a via into another layer of the circuit board, or adding decoupling capacitors. In HyperLynx PI, designers can again use a color-key map to identify problem areas then try out different solutions, or combinations of solutions. These can be brainstorming sessions, worked out before physical design even begins. Just as good design can be the foundation of good assembly and test, good PCB planning is the foundation of smart, optimized physical board layouts.

Mentor Graphics made the HyperLynx PI tool to cooperate with its signal integrity analysis software suite, HyperLynx SI, recognizing the heightened importance of power in the modern PCB. “Signal and power integrity should be part of the design from the beginning,” Isaac said. The goal of PCB designers should be minimizing layer count, keeping a lid on costs, speeding time-to-market through reduced design time and prototyping, and giving a board the highest possible reliability from the start by managing tolerances and limits. HyperLynx PI was designed to meet all of these goals, and also to be used by typical layout designers and electronic engineers, rather than just power integrity specialists. For more about the tool, see our coverage of the product release, read Mentor Graphics Debuts Power Integrity Analysis.

Meredith Courtemanche, managing editor