Learn from successful entrepreneurs and specialists at the annual Women’s Leadership Program.

We can find heroes all around us, but we will challenge you to look inside yourself and to not only identify your superpower but give you some tools to help define your personal brand. So, pick up your cape at the cleaners in time for the SMTA’s Women’s Leadership Conference at SMTA International. Show your support for diversity in engineering fields by joining us as we soar, explore and discover our very own Superheroes. The event is scheduled for Oct. 9 at the Minneapolis Convention Center.

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).

An experiment investigating print alignment adjustments.

Printed circuit board assembly requires extraordinary precision and repeatability. The screen printing process is considered the most critical process in the surface mount technology (SMT) assembly process. According to some studies, 70% of SMT defects can be traced back to the screen printing process (FIGURE 1). Component miniaturization has made this process more critical. Therefore, alignment of the apertures in the screen or stencil is key to an efficient and accurate solder paste transfer and there isn’t such a thing as local offset.

Figure 1. Solder paste defects, per Koh Young.

Claire Wemp is hot on the trail of better thermal interface materials and more engineering roles for women.

Thermal interface materials (TIM) are used between components to help with heat dissipation. Claire Wemp, Ph.D., is a thermal applications engineer at DuPont, with a doctorate in mechanical engineering, where her research was on heat transfer enhancement for metal surfaces. While an undergraduate, Wemp also became involved in the Society of Women Engineers, and continues to work with the nonprofit professional organization today. Wemp joined PCD&F/CIRCUITS ASSEMBLY on the PCB Chat podcast, where she discussed the use of TIMs and her work with SWE. What follows is a lightly edited transcript.