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Printed Circuit & Design Fab Circuits Assembly
November 2019
November 2019 • VOL. 36 • NO. 11
First Person
No dice for “chiplets.”
Mike Buetow
Money Matters
Guessing the next big thing.
Peter Bigelow

Talking to the vendor.
Greg Papandrew

Tech Talk
Additive manufacturing adds up.
Simon Fried
Automation isn’t just for the West.
Alun Morgan
Put down that 1080 glass now!
Bill Hargin
Coating components.
Bob Willis
New criteria for voiding and fill percentage.
David Bernard, Ph.D.
Total test coverage at the assembly level.
Andrew Vo
Needed: Solder joint forensic scientist.
Robert Boguski
November 2019 • VOL. 36 • NO. 11
After three decades in ECAD sales, some things haven’t changed at North America’s largest VAR.
by Mike Buetow

The Portland-based software company
is resolving return loss problems, one call at a time.
by Chelsey Drysdale

A study of the transfer efficiency and repeatability of several aperture designs for 0402, 0201 and 01005 discretes, and 0.4 and 0.5mm BGAs under lab and production conditions using multiple solder pastes.
by Chrys Shea, Jennifer Fijalkowski, Raymond Whittier, Michael Butler, Edward Nauss and Dean Fiato

Squeegee force is one of the many key factors required to achieve a good solder print, yet it interacts directly with the PCB support. A study of the effects of board support style on print stability and repeatability.
by Miguel Arroyo Colomer

IN the Digital Edition
The latest happenings among the IPC Designers Council chapters.

ON PCB CHAT (pcbchat.com)

All-Silicon Die Connection
SMT Solder Paste Printing
New ECAD SI/PI Tools
Reliability and DfM
Testing PCB Assemblies
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    Caveat Lector
    Mike Buetow Editor in Chief Image
    No Dice on ‘Chiplets’

    hen I first started in electronics back in 1991, through-hole was still dominant and SMT was just taking hold. It wasn’t long after, however, when we began hearing about multichip modules, or MCMs. Conferences sprung up, publishers dedicated entire issues to the subject, and trade groups started writing standards.

    And then … not much. MCMs never became the dominant packaging style some analysts predicted.

    But will they?

    When the Semiconductor Industry Association ceased its roadmapping activities, a host of organizations, including IEEE, SEMI, ASME and others, jumped in. Last month, they launched the second edition of the Heterogeneous Integration Roadmap. Heterogeneous integration refers to the integration of separately manufactured components into a higher-level assembly (SiP) that, in the aggregate, provides enhanced functionality and improved operating characteristics.

    Around the World
    PCD&F People
    Jamie Crichton Image
    FTG named Jamie Crichton vice president and CFO. He has extensive experience in finance leadership roles within the aerospace and defense sector, including Nanowave Technologies, Raytheon and Spar Aerospace.
    Nordcad Systems named Allan Norgaard senior application engineer.
    PCD&F Briefs
    Chunghwa Precision Test Tech will recruit 1,000 new employees for its new R&D headquarters to promote development of its ICT equipment.
    Around the World
    Altair Acquires PCB CAD Tool Developer Polliwog
    TROY, MI – Altair in October acquired EDA software developer Polliwog Co. for $11 million in cash, subject to customary working capital adjustments, and an aggregate of 473,752 shares of stock valued at about $48,000.

    Altair develops PLM, modeling and simulation tools primarily for the high-performance computing sector. Polliwog expands Altair’s portfolio for system-level engineering to the PCB design and analysis market. The products include a PCB modeler, simulation solvers and design verification tools. Polliwog’s customers include Samsung and LG Electronics.

    “The PollEx Modeler shares Altair’s open system philosophy and integrates easily into customer environments that use any of the leading PCB design tools and deliver innovative and practical solutions, a perfect fit for what we call simulation-driven design,” said James Scapa, chairman, chief executive and founder, Altair. “Polliwog’s powerful PCB modeler and design verification tools allow EDA engineers at small and enterprise customers to collaborate at never-before-seen levels and greatly expands our HyperWorks solution portfolio.”

    Altair pursued Polliwog as part of a strategy to expand from its foundation of mechanical simulation software into areas of systems simulation and electromagnetics. Polliwog’s PCB solvers and verification tools extend these capabilities, the firm added. – MB

    Around the World
    UP Media Group Announces 15% Spike in PCB West Conference Registration
    ATLANTA, GAConference attendance for PCB West 2019 was up 15% year-over-year, UP Media Group Inc. announced. Show organizers said the surge was tied to the now four-day conference, coupled with steady demand for the longer-form training sessions.

    PCB West, the largest conference and exhibition for PCB design, fabrication and assembly in the Silicon Valley, featured 59 presentations, a third of which were at least 3.5 hours in length. “It started with the record number of abstracts submitted, which gave us the opportunity to be more selective than ever,” said Mike Buetow, conference chairman. “Conference speakers were quick to notice the increase in attendance in their presentations.”

    The free sessions, which are not included in the conference registration, were also extremely popular, he added.

    Around the World
    Nano Dimension Presents Production-Grade Printed Capacitors for PCBs
    NESS ZIONA, ISRAELNano Dimension has developed 3-D printed capacitors using its DragonFly additive manufacturing system. These capacitors are embedded in the body of the additively manufactured PCBs, saving space and eliminating the need for assembly.

    Such capacitors are primarily used to filter electrical noise and ripple voltage for a wide range of applications, including RF transmission lines, audio processing, radio reception and power circuit conditioning.

    In internal testing, repeatability results show less than 1% variance, the company said. The technology uses the same dielectric and metal traces as in the additively manufactured PCB yielding capacitors with a capacitance range from 0.1nF to 3.2nF. The results are based on over 260 tests with 30 different additively manufactured capacitor dimensions.

    By integrating capacitors using additive manufacturing, the entire capacitor and PCB are printed as a single job. This cuts fabrication time and avoids many challenges imposed by traditional production techniques, Nano Dimension said. – CD

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    Around the World
    CA People
    Critical Manufacturing named Dave Trail vice president, Electronics segment. He has more than 25 years’ experience in electronics manufacturing equipment, processes and MES software.
    Justin Rohloff
    Kurtz Ersa named Justin Rohloff field service engineer. He has 13 years’ experience at Rockwell Automation as a process engineer technician.
    Karl Pfluke
    KIC hired Karl Pfluke as regional sales manager for Eastern US and Canada. He has a degree in manufacturing engineering and is SMT process engineer certified.
    MacDermid Alpha Electronics named Steve Williamson senior district sales manager.
    Mercury Systems named Scott Mazur senior principal quality systems engineer.
    Around the World
    Keynote, Mentor Teams Tackle Challenges Big and Small at SMTAI
    ROSEMOUNT, IL SMTA International kicked off in the Chicago suburbs in late September with a dazzling keynote and an innovative session on leadership.

    The keynote was a story of humility and doggedness. Adam Steltzner, Ph.D., the JPL engineer who led development of the Mars Curiosity rover, juxtaposed the development of that machine against his own background, which took him from high-school dropout and hippy musician to finishing first in his class in engineering at University of California, Davis. “Curiosity is our species’ superpower,” he told a rapt SRO audience. His team had to resolve all kinds of challenges with heat, weight and foreign matter to deposit the one-ton rover on the surface of Mars. Steltzner’s 45-minute narration was both self-deprecating and highly personal.

    A day earlier, the Women’s Leadership Program spent a half-day tackling the often-thorny situations newly minted engineers and aspiring managers must navigate. Women make up about 20% of the roughly 100,000 bachelor’s degrees awarded in engineering in the US, but despite the title, the program was applicable to any less experienced employee.

    Around the World
    CA Briefs

    Apple is reportedly planning to invest $1 billion to expand its local manufacturing in India.

    Aqueous Technologies appointed Restronics exclusive manufacturer’s representative in Northern California.

    Astronautics purchased a Takaya APT-1600FD-A flying probe tester.

    Compal is relocating production of US-bound notebooks to Taiwan from China.

    Electrolube held the grand opening of its 8,800 sq. m. manufacturing facility in Zhuji, Zhejiang province, China.

    EPFL scientists announced the creation of the world’s first robotic hand control – a new type of neuroprosthetic that unifies human control with artificial intelligence automation for greater robot dexterity.

    Inventec has invested $38 million to acquire a new plant in Taoyuan, Taiwan, to expand its local capacity.

    Market Watch
    IPC Survey: Global Electronics Industry Still Growing – Barely
    BANNOCKBURN, ILThe global electronics industry continues to thrive in a positive business environment, according to third quarter results from IPC’s Pulse of the Electronics Industry global data service.

    The survey still predicts continued growth over the next year, but results are somewhat less optimistic than in earlier 2019 quarters, and there are some sharp contrasts between regions. The composite score on the current state fell to its lowest level since the Pulse survey began in mid-2017.

    The companies’ average outlook for the next six months remains solidly positive on a global level but has weakened since the beginning of 2019. Europe is the only region reporting a net negative composite score on the industry’s six-month outlook. In the six-month outlook for Asia, only exports were rated as a negative driver this quarter, due to the trade war between China and the US.

    A Wave at the Future
    From additive manufacturing to autonomous vehicles, figuring out the next big thing is no small chore.
    With the last quarter underway and all eyes beginning to contemplate what and how to do better in the year to come, one of my focuses is trying to identify which technology will be the next big thing – one that will either transform or disrupt doing business as I know it.

    Over the past couple years politics seems to have been the biggest disrupter for all types of businesses. As challenging as it may be to identify the next tariff or tweet that may or may not send markets – and customers appetite to buy products – into a tailspin, the real challenge is trying to identify the next technological breakthrough that will either propel my business and the greater electronics industry forward or retard them into oblivion. Over the past dozen years many technological initiatives have been touted as game-changers; however, to date none has truly had the big bang effect on our industry.

    Board Buying
    A Good PCB Vendor Should Ask Questions
    Talk isn’t cheap, but the absence of it could cost you even more.
    Throughout my PCB career as a go-between for board buyers and manufacturers, I’ve often heard complaints from buyers that fabricators – domestic and offshore – ask too many engineering questions (EQs) after receiving an order. “Why can’t they just build the board?” buyers say.

    This mystifies me. In my view, PCB vendor questions provide valuable feedback. They may indicate the vendor lacks all the required information to build the order. They also tell me the manufacturer is intent on gathering all the data necessary to do the job right.

    I’d be more concerned if no EQs came from a vendor. A PCB has over 100 separate required manufacturing processes, almost all of which are unique to each customer. It would be surprising, even alarming, if everything in an order was absolutely clear, with no back-and-forth necessary.

    Designer’s Notebook
    Next-Generation Additive Manufacturing
    Non-planar designs and side-mounted components are next up for 3-D printing.
    It is true that even today, so many years after 3-D printing started to garner attention and acclaim, rapid prototyping remains the single most common use for 3-D printers. 3-D printers offer advantages in the form of shorter turnaround times, improved development secrecy and greater design freedoms. But it is also true 3-D printing isn’t going to remain primarily a tool for rapid prototyping much longer.

    Those keeping abreast of events in the worlds of design, construction, manufacturing or medicine will be keenly aware of the impact of additive manufacturing in these fields. Certain products have been rapidly affected by the arrival of additive manufacturing. Prime examples are hearing aids and dental aligners. Both markets have been transformed by the adoption of 3-D printing technologies. Additive is now the default manufacturing technology for such products.

    material gains
    Smart Manufacturing Technology Calls for Smart Investment
    If Southeast Asia has the lowest labor rates, why do they also have the best automation?
    Compared to highly visible “mass” markets such as automotive electronics and smartphones, it’s easy to think of the market for industrial electronics as “niche.” However, in total, about 23% of PCBs produced worldwide are used in electronics equipment for manufacturing applications. If we include categories that are obviously non-consumer, such as telecom equipment, data-center computing, and solar/wind-power conversion, storage, and smart-grid control within our concept of industrial electronics, it’s clear this sector is extremely important to the world’s electronics producers.

    As far as technology for manufacturing is concerned, we see organizations introducing digital transformation are profoundly changing the way they go about making, marketing, and supporting their products. Within this, smart manufacturing (aka Industry 4.0) leveraging cyber-physical systems, connected through the Industrial Internet of Things (IIoT), seamless linking of operational technology (OT) and IT infrastructures, intensive robotic process automation, and infusion of AI into edge devices and cloud services, is enabling companies to increase efficiency and agility, and improve standards of service delivery to customers.

    The Route
    Chapter Meetings Put a Fine Coating on Education
    Reports from San Diego, RTP and AltiumLive.

    As the second half of the year is quickly passing by, we have seen many continued activities in our industry regarding PCB design. From the PCB West conference held in mid-September in Santa Clara, CA, which was another huge success and always exceeds expectations, to AltiumLive 2019 held in early November in San Diego; both events were hugely successful and had great turnouts. We also have had some activity within our local IPC Designers Council (DC) chapters, such as the San Diego Chapter, which held its final chapter meeting for the year in late September. Here is a brief breakdown of these recent fall activities.

    San Diego Chapter

    Chapter leader: Luke Hausherr, CID+
    The San Diego Chapter held another successful meeting on Sept. 24 at San Diego PCB with 25 attendees. OrCAD EMA sponsored the event to help offset the cost of lunch. The highlight of the meeting was a presentation by Jeff Jenkins that covered conformal coatings. The content of the presentation was thorough and received positive feedback from all who attended. Jeff is a PCB chief technologist for L3Harris and has been involved in the workings of the PCB design, fabrication and assembly industries for over 23 years.

    Material Matters
    Why You Should Quit Using 1080 Glass
    The high percentage of resin coverage can cause skew issues at higher speeds.
    SINCE JUNE, I’VE been writing about glass-weave skew (GWS). If you haven’t read those articles, you may want to go back and bone up on the subject. We’ll review a few points here.

    A serial link’s differential-skew budget shrinks as bit rates increase. For example, a 1Gbps (500MHz) signal would have roughly 250ps of skew tolerance. That’s a wide window, and why most engineers didn’t need to worry about GWS 20+ years ago. Fast forward to 10Gbps (5GHz), and the skew tolerance will decrease proportionally to around 25ps.

    When working at frequencies below 1GHz, or when using whatever materials the fabricator has in stock due to schedule constraints, don’t worry about glass style. If signaling at higher speeds and there is time to plan, read on.

    Software Success Was a Leap of Faith
    After three decades in ECAD sales, some things haven’t changed at North America’s largest VAR. by Mike Buetow

    Before Manny Marcano came to ECAD software sales, he jumped out of airplanes as a paratrooper in the US Air Force. Taking risks, it seems, is in his blood.

    So, after selling tools for others in upstate New York in the mid-1980s – by his own account, he was a “lousy subordinate” – Marcano took the plunge. He cut a deal in 1989 to concentrate solely as a reseller of P-CAD and started EM Associates in his basement. As he recalls, “I pretty much was a one-man band. I got my family to stuff envelopes on the dining room table, and we did marketing things, but it was just old school, bootstrapping a business the hard way. There was no funding. I took a second mortgage on the house to fund the business. It’s a calculated risk that worked out.”

    Polar Instruments
    Polar ‘Opposites’: Software Co. Ties Tight Design-Fab Link
    Resolving return loss problems, one call at a time. by Chelsey Drysdale

    Usually when presidents retire, they have a party and go home. Not Ken Taylor. He has stepped down as head of Polar Instruments’ North American business unit three times and counting, but he keeps showing up to the office. Having an “enjoyable relationship with everybody makes it a great place to come to work,” he told PCD&F during a visit to Polar’s sales office near Portland, OR.

    That elasticity has served both him and the company well. Polar’s approach to customers is help them all, whether they have recently purchased one of the company’s impedance or signal integrity software tools, or use older or obsolete products, or even don’t use Polar products at all. Says Taylor: “Our objective is to have a satisfied customer base that speaks well of us.”

    In Portland, Taylor, Geoffrey Hazelett, vice president sales, and Lupita Maurer, product specialist, were eager to answer questions about the company Taylor says doesn’t have “a single unhappy customer or user.”

    Screen Printing
    Comparison of Aperture Designs, Solder Pastes, Nanocoatings and Print/Inspection Systems
    Testing transfer efficiency and repeatability for microminiature devices down to 01005 discretes and 0.4mm BGAs. by Chrys Shea, Jennifer Fijalkowski, Raymond Whittier, Michael Butler, Edward Nauss and Dean Fiato

    High-reliability PCB assemblers face multiple challenges from the mainstream industry’s migration to lead-free solders. One of the major challenges is in the solder paste itself. Solder paste manufacturers have been continuously developing new lead-free solder pastes for approximately 15 years. Few, if any solder suppliers, have introduced new SnPb solder pastes however, due largely to low market demand. Even if better SnPb paste formulations were available, changing them in a mission-critical application would require a great deal of due diligence and qualification testing.

    The overall approach to SMT process optimization starts at the front of the assembly line and reviews each individual process moving down the line. Therefore, the method of optimizing production of discrete sizes 01005 to 0402 (Imperial) starts with optimizing the print.

    Screen Printing
    Dedicated vs. Flexible Board Support
    A good seal between stencil aperture and solder pad ensures the best solder paste deposition. by Miguel Arroyo Colomer

    Enhanced functionality demanded by today’s increasingly miniaturized PCBAs has added to their complexity and density but has also decreased their rigidity. PCBs used to be more rigid and less dense. Solder printing of double-sided boards was performed using standard support pins. In some cases, customized tooling was required to ensure board support.

    Today, dedicated tooling and flexible support systems are more frequently employed than ever before. They are easy to set up and provide excellent support. This is in part because the support pins typically supplied with the printer are often perceived as being too difficult to set up, and there never seem to be enough to properly support the board.

    Ideal forces at one point. Note there are only two forces, each cancelling the other
    Figure 1. Ideal forces at one point. Note there are only two forces, each cancelling the other.
    Defect of the Month
    Conformally Coated Chip Caps
    While coatings are typically used on boards, some choose to coat components as well.
    This month we show manual conformal coating on one component. One optical example is shown under normal lighting and then under UV light, to show the tracer added in coatings to allow easy manual or automatic inspection. This is not a defect. I asked if this was intended, however, as it was unusual.

    Traditionally, coatings are used to protect circuit boards in humid environments and more so in condensing conditions to prevent corrosion. On some occasions design engineers also use coatings to provide that little stability.

    A capacitor manually coated with conformal coating under normal lighting.
    Figure 1. A capacitor manually coated with conformal coating under normal lighting.
    The same capacitor under UV light.
    Figure 2. The same capacitor under UV light.
    Test and Inspection
    Clarifying Through-Hole Fill Levels
    IPC-STD-001 is revising criteria for voiding and fill percentage.
    In my September column, I spoke with Dave Hillman about IPC committee work on voiding guidelines for QFN central pad terminations. But he also told me the J-STD-001 task group increasingly receives requests from users for additional information and clarification of x-ray usage in other areas. This is because use of x-ray technology for analyzing solder joints has resulted in significant soldering process improvements. As with all technology introductions, however, the benefits and questions that result from the new information provided must be characterized, assessed and disseminated into practical form. One such area where x-ray technology has provided a tremendous amount of new information is plated through-hole (PTH) solder joints. The “insides” of these joints were previously “hidden” from scrutiny, unless subject to destructive methods, and the standards writers will need time to carefully revise old criteria to accommodate this new information. With this in mind, IPC formed a task group (called Team Skeleton) to discuss this and other matters, with the goal to develop additional x-ray-related guidelines and requirements for inclusion in future IPC documentation. As usual, Dave says, “All are welcome to participate and provide their comments and suggestions.”
    Thinking Lean in Test Strategy
    Methods for 100% test coverage at the assembly level.
    While Lean manufacturing strategy is discussed in relation to test strategy, it often focuses on defect mitigation strategies such as integrating program, pack and test activities to minimize variation and transport. However, a Lean manufacturing philosophy can provide even better guidance as companies navigate test strategy options. There is one hurdle to overcome. Google the question, “Is test a value-added activity?” You will see answers in Lean manufacturing forums that range from “if the process is in control you don’t need to test” to “yes, if the customer is willing to pay for it.”

    The reality is that in the electronics industry there are very real reasons robust inspection and test strategies are necessary. And, when the cost of field failures is fully considered, a robust inspection and test strategy eliminates much non-valued-added cost. One of the reasons 3-D solder paste inspection (SPI) has gained in popularity is companies have come to understand that the quality of solder paste disposition has a huge impact on whether there are workmanship-related defects later in the process. Screen for variations at that point, and a large percentage of potential defects are eliminated before components are attached to the PCB. Similarly, in-process inspection by automated optical inspection (AOI) and x-ray help screen out workmanship defects before product gets to test. In fact, the argument that a production line with tight process control and a series of inline inspections won’t generate workmanship-related defects is valid and is often used to justify little or no additional testing between the electronics contract manufacturer and the customer in outsourcing scenarios. The fallacy with that argument is it presumes that PCBAs are populated with 100% known good components. The reality is that while component quality has improved immeasurably since the days when contract manufacturers performed 100% component screening in incoming inspection, the rigors of shipment and high-temperature processing do create bad components. Legacy products have even higher risks in this area, since they often use aging component inventories.

    Want CSI for Engineers? Inquire Within.
    Needed: Solder joint forensic scientist. Common sense preferred.
    Wanted: X-ray engineer. A test engineer with an interest in x-ray technology will suffice. So will a skilled and teachable technician. Hell, an intelligent person with a pulse will do in this economy. We’re open-minded. Just show us. No shrinking violets here. Honesty still matters to us (like being honest about the state of the economy and its effects on available talent). You should be honest, too, if you’d like us to hire you. Bring the aptitude; we’ll give you the qualifications.

    We will train you.

    Job description: People will bring you stuff. Usually that stuff doesn’t work. It just sits there passively when power is applied to it. The handover is usually not a happy occasion. (Note severely furrowed brow of customer as they hand you the malfunctioning item.) Check facial expression and nervous laughter of the person delivering the stuff. It conceals little. Much rides on the diagnosis (their job, perhaps). Failure in this instance is a career option for you. Diagnosing the source, that is. You just need to find the defective solder joint.

    Off The Shelf
    Off The Shelf
    Machines Materials Tools Systems Software
    Internet-Enabled ECAD
    eCADSTAR is an internet-connected PCB design platform. Combines 2-D/3-D electronic design with inbuilt internet capabilities and predictive tool tips and prompts. Provides borderless electronic design environment that connects engineering with online services that streamline global design review and manufacturing processes. Searches online component vendor libraries, requests quotes and purchases parts from within design tool.
    FEA/CFD Analysis
    Celsius Thermal Solver combines finite element analysis for solid structures with CFD for fluids to enable complete system analysis in a single tool. In conjunction with technology for PCB and IC packaging, combines electrical and thermal analysis and simulates flow of electricity and heat for system-level thermal simulation. Performs static (steady-state) and dynamic (transient) electrical-thermal co-simulations based on actual flow of electrical power in advanced 3-D structures, providing visibility into real-world system behavior.
    CAD FOR HDI Routing
    Altium Designer 20 features new “push and shove” capabilities that enable routing of complex HDI boards and speed design times over 20%. New advanced routing enables efficient design of high-density and high-speed boards that utilize DDR3/4/5, 100GB ethernet and SerDes PCIe 4.0/5.0. Leverages ActiveBOM capabilities, including supplier search, BoM rule checking, and live part choices for multi-board assemblies. Exports 3-D PDF files of the multi-board assembly.
    Off The Shelf
    Off The Shelf
    Machines Materials Tools Systems Software
    3-D AOI
    SIR Reliability Tester
    OE-200 SIR electrical test tool measures reliability per IPC J-STD-001G, amend. 1 in real-time on shop floor. Plug-and-play design tests reliability as needed and compares to historical test data. Real-time analytics and reporting. Works in conjunction with an environmental temperature-humidity chamber.
    Easy-Clean Paste Retainer
    PLX-PR-DT paste retainer, gen. 4, incorporates new features and functions for SMT printing. Provides adjustability, up-down positions and left-right positions. Enables users to loosen and remove paste retainer for cleaning during product changeover. Features parallel leaf spring configuration, with a soft spring load in z direction that permits paste retainer to ride close to stencil or in contact with stencil without causing damage to or coining of foil.
    Transition Automation
    3-D AOI
    3-D AOI
    Zenith Alpha 3-D AOI collects, analyzes and manages data in real-time to dynamically formulate a multifaced view of assembly process. Provides reliable 3-D measurement. Supports KSMART factory optimization software suite, which integrates process management by linking SPI and AOI to production results. Automatically creates inspection programs 70% faster than before.
    Koh Young
    Technical Abstracts
    In Case You Missed It
    “Goodbye, Motherboard. Hello, Silicon-Interconnect Fabric”

    Authors: Puneet Gupta, Ph.D. and Subramanian S. Iyer, Ph.D.

    Abstract: The need to make some hardware systems smaller and others bigger has been driving innovations in electronics for a long time. The former can be seen in the progression from laptops to smartphones to smart watches to hearables and other “invisible” electronics. The latter defines today’s commercial data centers – megawatt-devouring monsters that fill purpose-built warehouses around the world. Interestingly, the same technology is limiting progress in both arenas, though for different reasons. The culprit is the printed circuit board. And the solution is to get rid of it. The authors’ research shows PCBs could be replaced with silicon. Such a move would lead to smaller, lighter-weight systems for wearables and other size-constrained gadgets, and to incredibly powerful high-performance computers. This all-silicon technology, called silicon-interconnect fabric, allows bare chips to be connected directly to wiring on a separate piece of silicon. Unlike connections on a printed circuit board, the wiring between chips on the fabric is just as small as wiring within a chip. Many more chip-to-chip connections are thus possible, and those connections are able to transmit data faster while using less energy. (IEEE Spectrum, Sept. 24, 2019)

    Thanks for reading our November 2019 issue!