Designing a circuit board is both an art and science. So what’s needed to ensure a perfect design? I’ll lay it out here in five steps.

First, paying attention to PCB design is crucial for avoiding problems later. Creating a PCB is like conceiving the digital image and translating it into a physical entity. Thus, the circuit board design needs to be realistic enough to put on paper and convert into a tangible form.

1. Refine the component placement plan

While a PCB is not as vast as a landscape, you’re given a challenge to do wonders on a small piece of metal board. So, it’s important to ensure that the component placement plan is repeatedly revised to achieve the best use of the PCB. Hence:

Pay attention to orientation: As a general rule, your PCB design should have similar components placed in a common orientation. This helps a lot during the soldering process, and errors are reduced.

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How we use and generate electricity has changed dramatically over the past century yet the basic components that control its flow remain remarkably similar. Researchers at KAUST have now developed a novel type of component that could improve the performance of electrical circuits.

Electronic circuitry is traditionally constructed from three primary elements; a resistor, a capacitor and an inductor. A sinusoidal electrical signal passing through these devices will change in signal strength, or amplitude, and the relative timing of the crest of the wave, known as its phase. A resistor will change amplitude only while a capacitor and an inductor can also change phase, but only by exactly one quarter of the length of the wave, or 90°.

Components that could alter the phase of the electrical signal by a different amount would enable electrical circuits with more varied functionality. One such device, known as a fractional-order capacitor, was realized by electrical engineering doctoral student Agamyrat Agambayev, under the supervision of Hakan Bagci and Khaled Salama, and colleagues. “We use a solution-casting method to fabricate fractional-order capacitors,” explains Salama. “This method allows us to easily blend different polymers and provide a mechanism to tune the device’s properties.”

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Space savings, greater reliability, low mass, and high ductility are some of the advantages offered by flexible PCBs, but designers must also prepare for their complexity.

Printed-circuit-board (PCB) substrate material, like FR-4 glass epoxy, is a poor conductor of heat. Conversely, copper is an excellent conductor of heat. So, more copper area on a PCB is ideal from a thermal-management perspective.

Therefore, it’s very important to create a mechanical model of the PCB and test it for a proper fit, before taking up the electrical design. This would also involve testing the ergonomics of the installation, any misalignments, and servicing. In addition, it necessitates that designers understand the different types of flex circuits available and the way they work.

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Eventually, almost every EE must design a PCB, which isn’t something that’s taught in school. Yet engineers, technicians, and even novice PCB designers can create high-quality PCBs for any and every purpose with confidence that the outcome will meet or exceed the objective.

Virtually every electronic product is constructed with one or more printed-circuit boards (PCBs). The PCBs hold the ICs and other components and implement the interconnections between them. PCBs are created in abundance for portable electronics, computers, and entertainment equipment. They are also made for test equipment, manufacturing, and spacecraft.

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In Part 2, we explore best PCB-layout practices for a variety of motor-driver package types.
Part 1 of this article provided some general recommendations for designing printed-circuit boards (PCBs) using motor-driver ICs, which require careful PCB layout for proper performance. Part 2 discusses some specific PCB layout recommendations for using typical motor-driver IC packages.

Standard leaded packages, like SOIC and SOT-23 packages, are often used for low-power motor drivers

To maximize the power-dissipation capability of leaded packages, Monolithic Power Systems (MPS) uses a “flip-chip on leadframe” construction (Fig. 7). The die is bonded to the metal leads using copper bumps and solder without the use of bond wires. This allows heat to be conducted from the die through the leads to the PCB.

In Part 1, we’ll discuss some general recommendations for designing PCBs that use motor-driver ICs, which require special cooling techniques to handle the power dissipation.

Printed-circuit-board (PCB) substrate material, like FR-4 glass epoxy, is a poor conductor of heat. Conversely, copper is an excellent conductor of heat. So, more copper area on a PCB is ideal from a thermal-management perspective.

Thick copper, like 2-oz. foil (68 microns thick), conducts heat better than thinner copper. Unfortunately, using thick copper is expensive, and makes it difficult to achieve fine geometries. Therefore, the use of 1-oz. (34 microns) copper has become commonplace. For external layers, this is often ½-oz. copper plated up to 1-oz. thickness.

Solid-copper planes used on inner layers of multi-layer boards work well to spread heat. However, since these planes are normally placed in the center of the board stack-up, the heat can get trapped inside the board. Adding copper areas on the outer layers of the PCB and placing many vias to connect, or “stitch,” these areas to the inner planes helps transfer heat out of the planes. 

On two-layer PCBs, spreading heat may prove more difficult due to the presence of traces and components. Providing as much solid copper as possible with good thermal connections to the motor-driver IC is a necessity. Putting copper pours on both outer layers and stitching them together with many vias helps spread the heat across areas cut by traces and components. 

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