Written by Douglas Brooks, Ph.D., Johannes Adam, Ph.D., and Ulisses Castro
Category: Features
Signal traces internal to the board change temperature along their length, changing resistance.
In our recent book,1 an image shows how heat from a relatively hot trace flows downward through the board (FIGURE 1). What is important to recognize here is how little horizontal heat dispersion there is. The heat seems to flow straight down. What thermal images like this obscure is the relative horizontal and vertical scales. The horizontal width in this image is 50mm, while the vertical height is less than 2mm. Not enough room is underneath the trace for much horizontal dispersion. Consequently, the temperature of the bottom layer of the board directly under the trace is only a few degrees cooler than the temperature of the top layer, regardless of what is beneath the top layer.
RIT and industry have developed a novel curriculum for teaching PCB design. Is this the start of a college trend?
We are always interested in the approaches being taken to recruit and train the next generation of engineers. Readers may recall last summer we did a podcast with a group of recent graduates from the Rochester Institute of Technology’s Capstone program. There, the students conceive, design, source and build electronics hardware as part of a senior project. It’s truly a great way to immerse themselves in what a career in our industry could look like.
What we didn’t mention was RIT is launching another hands-on program. This one focuses on printed circuit board design. The first class started in January with 25 students. Chris Banton, director of marketing at EMA Design Automation, and Dr. James Lee, acting chair of the Electrical and Computer Engineering Technology department at RIT, explained what spurred the program and what it hopes to accomplish.
An Ohio community college breaks the mold with an applied bachelor’s degree in electronics manufacturing.
In my three decades in electronics engineering, perhaps the only thing that never changes is the need for more skilled workers. No matter the state of the economy or the geography, having knowledgeable and competent engineers and operators is always critical, and there are never enough of either.
But while the tension is notable between industry and academia over who is responsible for preparing the next generation of workers for specific tasks, some schools are quietly taking the lead by putting in place programs that include true hands-on training in printed circuit board manufacturing.
I’m talking specifically about Lorain County Community College. Lorain is in Northeast Ohio, about 30 miles west of Cleveland.
“Chips don’t float,” the saying goes, but it’s up to the PCB industry to push its message to Washington.
It’s hard to believe now, but veterans of the printed circuit board industry will remember when the US was neck and neck with Japan as the largest PCB manufacturing market. It peaked in 2000-2001 with sales north of $10 billion each year and close to a 30% share of the overall market.
How things change.
Today, US domestic PCB manufacturing output is around $3 billion, and its share of the global market is in the mid-single digits. Meanwhile, China has surged ahead of the pack, as more than half the bare boards produced each year are built on the mainland. Moreover, nations like Vietnam that didn’t even register a decade ago are now larger than the US market.
Ed.: This is a special feature courtesy of Binghamton University.
Next-gen chips will be powered from below. As transistors continue to be made thinner, the interconnects that supply them with current must be packed closer, which increases resistance and power. In processors, both signals and power reach the silicon from above. Arm researchers have developed a technology that separates those functions, saving power and making more room for signal routes. The signals travel along the copper traces of a PCB into a package that holds the SoC, through the solder balls that connect the chip to the package, and then via on-chip interconnects to the transistors. These interconnects are formed in layers called a stack. It can take a 10- to 20-layer stack to deliver power and data to the billions of transistors on today’s chips. (IEEC file #12450, IEEE Spectrum, 9/2/21)
Using liquid metal to turn motion into electricity, even underwater. North Carolina State University researchers have created a soft, stretchable device that converts movement into electricity and works in dry and wet environments. The heart of this energy harvester is a liquid metal alloy of gallium and indium. The alloy is encased in a hydrogel with the water containing dissolved salts (ions). The ions assemble at the surface of the metal, which induces a charge in the metal. Increasing the area of the metal provides more surface to attract a charge. This generates electricity, which is captured by a wire attached to the device. Researchers found that deforming the device by only a few millimeters generates a power density of approximately 0.5 mW/m-2, comparable to popular classes of energy harvesting technologies. (IEEC file #12449, Science Daily, 8/28/21)
Stop designing products guaranteed to fail EMC testing.
Au: This article emphasizes the need to concentrate on design of transmission lines, or the “spaces,” instead of the “wires.” The industry focus has been on the movement of charges in the wires, which only occurs because the electric fields are moving. The energy is carried by the fields, not the displacement current. My apologies to the EM physicists for oversimplifying these concepts, but this approach will increase the chances of success for most designs.
Engineering teams worldwide are facing increasingly difficult challenges to design electronic products and achieve good signal integrity and compliance. However, the status quo is to expect the design to fail EMC testing not once, but three, four, or as many as five times. Each time the design is sent to be retested, there is little confidence in success. This cycle is expensive in both the time it takes to redesign the product and the cost of expediting fabricating the new PCB and assembly. Add this to the cost of retesting the product, and the numbers add up very quickly. This expense and delay in product certification are not in the budget or the schedule. The cost not only directly affects the bottom line of the electronic supply company, but also affects the customers waiting for the product. Instead of designing the next big thing, teams are trying to fix the current one. As a result, billions of dollars are lost each year designing products that are expected to fail.
What is wrong here? The billion-dollar mistake.
The billion-dollar mistake is rooted in the misunderstanding of the nature of electronic energy. One drawing is to blame.
