Features

New 3-D technologies with robust interconnects and thermal solutions are on the way.

Ed.: This is the fifth of an occasional series by the authors of the 2019 iNEMI Roadmap. This information is excerpted from the roadmap, available from iNEMI (inemi.org/2019-roadmap-overview).

Aerospace and defense (A&D) products face several challenges unique to this particular market segment, including the extreme environments in which they operate, need for security, desire for reworkability, long duration storage requirements and the functional lifetime over which the products are expected to perform and be supported.

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Updates in silicon and electronics technology.

Ed.: This is a special feature courtesy of Binghamton University.

Transistors can process and store information. Purdue University researchers have created a feasible way to combine transistors and memory on a chip, potentially bringing faster computing. They used a semiconductor that has ferroelectric properties. This way two materials become one material, and without worry about the interface issues. The result is a so-called ferroelectric semiconductor field-effect transistor, built in the same way as transistors currently used on computer chips. The material, alpha indium selenide, not only has ferroelectric properties, but also addresses the issue of a conventional ferroelectric material usually acting as an insulator rather than a semiconductor due to a so-called wide “band gap,” which means that electricity cannot pass through and no computing happens. (IEEC file #11468, Science Daily, 12/9/19)

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Or should we just isolate noisy signals?

There are several theories about whether a differential pair should be routed with tight coupling or loose coupling. There must be some science that can be drawn on to arrive at a rule set that makes best use of layout time, while optimizing the signal integrity of a differential pair. This article explores the advantages of tight and loose coupling.

A known industry speaker says, “Everybody knows tight coupling is best for differential signaling.” This is stated in a tone of voice that implies those who don’t know this might be lacking. I sometimes say I am from Missouri, which is the “Show-Me State.” If the need for tight coupling is true, perhaps there is some proof. I am still waiting to see it. The following discussion will look at a tightly coupled differential pair and the same pair loosely coupled.

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Or does it distract from the actual need of the signaling protocol?

Much engineering time is spent on designing differential signaling circuits to maintain a differential impedance between the two sides of the differential pair. A similar amount of time is spent measuring the final PCBs to ensure the differential impedance specification is met. The most common differential impedance target is 100Ω. A fair question is whether this impedance requirement is necessary. Once differential signaling is understood, it will be seen as unnecessary and distracting from the actual need of the signaling protocol. This article will clear up this confusion.

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Stephen Chavez

In this month’s column, we’ll take a first look at the new Printed Circuit Engineering Association (PCEA), including an overview of membership and why we established the organization. We’ll also look at the mission of PCEA, and how it will unfold to the industry.

Membership. PCEA is an international network of engineers, designers, and specialists related to printed circuit development. We are a mixed group of individuals that covers the entire product development cycle. There are no limitations or restrictions as to who can become a member. Membership is free and open to all those interested in gaining and sharing their knowledge with others. We will serve the industry as a nonprofit organization.

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In the wake of pandemics and travel bans, visitors still turned out for the annual exhibition.

Heading into IPC Apex Expo the first week of February, I wasn’t sure what to expect. The overall market appears to be slowing somewhat. Many EMS companies have reported lower sales for the past quarter. US presidential elections often seem to dampen electronics orders, at least until November, even though a review of the overall GDP disputes any such letup. And fears of the coronavirus in China have clearly spooked the industry, as some firms have reduced or banned employee travel for the time being.

But once the show started, many of those concerns abated. Floor traffic was up and down through the first two days, before grinding to a near halt per usual on the third and final day of the show. Exhibitors took note, reporting mixed reviews of the attendance. But when it was busy, it was really busy. It’s hard to say whether the postponement of overseas shows such as Nepcon China and the International Electronic Circuits (Shanghai) Exhibition (better known as the CPCA Show) boosted attendance an ocean away in San Diego, but it probably didn’t hurt. (On Mar. 2, IPC reported 4,211 visitors attended the show, down 20% from a year ago.)

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