Features

An overview of the physical and electrical characteristics of rigid and flex laminates.

Electronic devices functioning at high frequencies are currently evolving at a dizzying pace, particularly within the field of wireless communication. When developing new products, therefore, emphasis is placed on utilization of materials suitable for high-frequency work, above 1GHz.

When selecting materials intended for high-frequency printed circuit boards, several characteristics are of importance:

  • Dielectric constant (Dk) – dielectric coefficient of the resin. This parameter must be low and stable within a wide range of high frequencies. High Dk values may decelerate signal transfer speed.
  • Dissipation factor (Df) – the parameter responsible for the signal's quality. The Df value should be low. The lower this value, the more stable the signal, and losses will be reduced.
  • Moisture absorption – another imperative parameter when selecting materials intended for high frequencies. This is important because the Dk of water is Dk;water = 80.4, a value so high, in fact, the absorption of very small amounts of moisture will instigate a significant increase in the overall Dk of the material.
  • Coefficient of thermal expansion (CTE) – thermal dimensional expansion parameter of the dielectric material. This parameter must be close to the CTE of the conductive metal; in the case of PCBs, it is copper. Working at high frequencies causes increased heating of the PCB and thus if a significant discrepancy exists between the CTE of the dielectric material and the copper, structure delamination may occur during the activation of heating/cooling cycles.
  • Additional important parameters such as:
    • Thermal resistance.
    • Chemical resistance.
    • The adhesion strength between copper and the dielectric material.
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Massive investment suggests the segment could occupy a major portion of the largest fabricators' production.

The heartbreak of the pandemic of 2020-21 is receding, but printed circuit fabricators continued to feel the supply-chain reverberations throughout the past year. The rollercoaster gyrated from a sharp dip to an intense high, with demand for consumer electronics, autos and other electronics resulting in tight inventories and long lead times. Then came the inevitable slowdown. Regionalization, currency swings and price cuts played havoc with manufacturers' order books and financials.

That's the picture drawn by this, the 26th NTI-100 report. As in the past several years, a rough conclusion is "big gets bigger and faster." Due to exchange rates that were favorable to the US dollar in 2022, the author thought there would be changes in the rankings, but they remained approximately the same as in 2021. Japanese fabricators were a surprise. Despite a 20% loss in value against the US dollar, their world ranking remained almost the same as in 2021. Domestic customers wanted to get PCBs from within the country because of supply-chain disruptions in China, resulting in good order intake.

As in the past, the author would like to thank various trade organizations and many firms and friends who provided vital information that enabled the compiling of this report. Any errors in this report are the responsibility of the author.

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With new leadership at the helm, Freedom CAD is looking to the future while maintaining its standards.

Freedom CAD has been offering electronic product development and PCB design services since its inception in 2003, but the core team behind the company has been together since the early '90s.

That leadership has built the company into one of the largest design service bureaus in the US, offering design and engineering services for more than 150 customers per year – many of whom have been customers since the early days.

"We have a long history, and with that, we have a long history with our customers," said COO Scott Miller.

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Enhanced insulated metal substrates are effective for wide-bandgap semiconductor power modules.

Step on the pedal of a modern electric vehicle (EV) and you will feel quick, smooth acceleration. This smooth acceleration is due to improvements in converting DC battery energy into three-phase AC power that controls torque and speed. Although most headlines focus on advancements in EV battery design, it is improvements in power switching in the traction inverter that has led to better performance and power management in the vehicle's propulsion system.

The demand for advanced high-performance power systems is far-reaching. Many industries are searching for innovative materials and technologies that will meet the needs of next generation power electronics. Trends in the marketplace are toward more compact power devices that can operate under extreme conditions. Higher temperatures, higher switching frequencies and higher blocking voltages are in demand, while efficiency and reliability issues are obstacles that need to be overcome.

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A design, equipment, process and materials methodological approach.

Electronics for automotive applications, as well as for other industries, are expected to reliably operate in harsh environments at a competitive cost. Advances in safety, communication and displays are driving miniaturization and integration of sub-devices onto the PCB assembly; e.g., cameras, sensors, and LEDs. Electrification trends are also leading to higher voltage requirements. In one example of a harsh environment application, automotive door and window control modules may have a critical circuit or component that is desired to function for a specified amount of time, even while submerged in water.

This paper describes an enabling technology to assist in the protection of critical functionality on PCB assemblies. 3-D-printed plastic retaining or "barrier" walls are formed to precisely control the location and height of a dispensed encapsulant in a region of the circuit that is sensitive to the environment. A case study was undertaken for the creation of 3-D-printed retaining walls, formed directly onto the surface of PCB substrates, without the need for separate parts, mold tools, mechanical or liquid fasteners, and complex manufacturing equipment. Also eliminated is the need to encapsulate or pot the entire PCB assembly, which adds additional complexity and cost. The encapsulant-filled retaining wall structure protects critical circuits from chemical, mechanical and electrical external factors such as moisture, fluids, gasses, particulate contamination, physical contact, or arcing in applications requiring high voltage. A 3-D model of the SIR test PCB having a representative retaining wall structure, surrounding an interdigitated test circuit, is shown in FIGURE 1. The retaining walls hold a liquid-dispensed encapsulant in place, at a predetermined height. In the absence of a retaining wall structure, as shown in FIGURES 2 and 3, an encapsulate can spread uncontrollably across the surface of the PCB (Figure 2), or result in insufficient height of the encapsulant, exposing electronics circuitry (Figure 3).

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Compensation continues to rise among PCB designers.

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