Technical Library | 2020-08-13 00:59:03.0
The paper will discuss the integration of 3D printing and inkjet printing fabrication technologies for microwave and millimeter-wave applications. With the recent advancements in 3D and inkjet printing technology, achieving resolution down to 50 um, it is feasible to fabricate electronic components and antennas operating in the millimeter-wave regime. The nature of additive manufacturing allows designers to create custom components and devices for specialized applications and provides an excellent and inexpensive way of prototyping electronic designs. The combination of multiple printable materials enables the vertical integration of conductive, dielectric, and semi-conductive materials which are the fundamental components of passive and active circuit elements such as inductors, capacitors, diodes, and transistors. Also, the on-demand manner of printing can eliminate the use of subtractive fabrication processes, which are necessary for conventional microfabrication processes such as photolithography, and drastically reduce the cost and material waste of fabrication.
Technical Library | 2020-11-19 20:35:26.0
Simultaneously with the first complex electronic circuits, the task of creating effective means of diagnosing and repairing them appeared. In previous decades, specialized programmable stands were used for diagnostics of serial electronic products, as well as various testers and probes for troubleshooting during their operation. But the dramatic increase in the density / cost factor, in parallel with the very rapid modification of electronic products, made programmable stands economically ineffective even in mass production. The use of traditional laboratory equipment (oscilloscopes, multimeters, etc.) requires power supply to the defective modules, which is often impossible and unsafe, since it can lead to failure of the working modules of the module. In addition, the use of this equipment requires documentation and highly qualified personnel. More automated and sophisticated signature analysis systems came to the rescue in solving this problem. A feature of these devices is that they allow you to test digital and analog assemblies without dismantling components and without supplying voltage.
Technical Library | 2021-05-26 00:53:26.0
This paper describes a copper electroplating enabling technology for filling microvias. Driven by the need for faster, smaller and higher performance communication and electronic devices, build-up technology incorporating microvias has emerged as a viable multilayer printed circuit manufacturing technology. Increased wiring density, reduced line widths, smaller through-holes and microvias are all attributes of these High Density Interconnect (HDI) packages. Filling the microvias with conductive material allows the use of stacked vias and via in pad designs thereby facilitating additional packaging density. Other potential design attributes include thermal management enhancement and benefits for high frequency circuitry. Electrodeposited copper can be utilized for filling microvias and provides potential advantages over alternative via plugging techniques. The features, development, scale up and results of direct current (DC) and periodic pulse reverse (PPR) acid copper via filling processes, including chemistry and equipment, are described.
Technical Library | 2023-11-06 17:08:44.0
A new process has been developed for RF shielding on compact electronic communications devices using automated solder paste dispensing. The process is known as Shield Edge Interconnect (SEI). SEI designs enable parts to be processed though underfill before placing of the RF shield and allows more complete use of valuable PCB real estate to achieve reduced form factor requirements and/or for added components on products such as smartphones and tablets. The reduced form factor creates challenges for the assembly of those devices. This process, enabled by Speedline dispensing technology, relies on extremely accurate dispensing of solder paste on copper traces located along the outer edge of the PCB. The result is a robust process solution for SEI in which proprietary closed loop dispenser, pump, vision, and software technologies enable a high volume manufacturing (HVM) process.
Technical Library | 2019-08-29 13:04:55.0
The true integration of electronics into textiles requires the fabrication of devices directly on the fibre itself using high-performance materials that allow seamless incorporation into fabrics. Woven electronics and opto-electronics, attained by intertwined fibres with complementary functions are the emerging and most ambitious technological and scientific frontier. Here we demonstrate graphene-enabled functional devices directly fabricated on textile fibres and attained by weaving graphene electronic fibres in a fabric. Capacitive touch-sensors and light-emitting devices were produced using a roll-to-roll-compatible patterning technique, opening new avenues for woven textile electronics. Finally, the demonstration of fabric-enabled pixels for displays and position sensitive functions is a gateway for novel electronic skin, wearable electronic and smart textile applications.
University of Exeter, College of Engineering, Mathematics and Physical Sciences
Technical Library | 2020-10-14 14:33:36.0
Epoxy based adhesives are prevalent interface materials for all levels of electronic packaging. One reason for their widespread success is their ability to accept fillers. Fillers allow the adhesive formulator to tailor the electrical and thermal properties of a given epoxy. Silver flake allow the adhesive to be both electrically conductive and thermally conductive. For potting applications, heat sinking, and general encapsulation where high electrical isolation is required, aluminum oxide has been the filler of choice. Today, advanced Boron Nitride filled epoxies challenge alternative thermal interface materials like silicones, greases, tapes, or pads. The paper discusses key attributes for designing and formulating advanced thermally conductive epoxies. Comparisons to other common fillers used in packaging are made. The filler size, shape and distribution, as well as concentration in the resin, will determine the adhesive viscosity and rheology. Correlation's between Thermal Resistance calculations and adhesive viscosity are made. Examples are shown that determination of thermal conductivity values in "bulk" form, do not translate into actual package thermal resistance. Four commercially available thermally conductive adhesives were obtained for the study. Adhesives were screened by shear strength measurements, Thermal Cycling ( -55 °C to 125 °C ) Resistance, and damp heat ( 85 °C / 85 %RH ) resistance. The results indicate that low modulus Boron Nitride filled epoxies are superior in formulation and design. Careful selection of stress relief agents, filler morphology, and concentration levels are critical choices the skilled formulator must make. The advantages and limitations of each are discussed and demonstrated.
Technical Library | 2019-09-04 21:35:53.0
Since the European Directives, RoHS (Restriction of Hazardous Substances) and REACH (Registration, Evaluation, Authorization and Restriction of Chemicals), entered into force in 2006-7, the number of regulated substances continues to grow. REACH adds new substances roughly twice a year, and more substances will be added to RoHS in 2019. While these open-ended regulations represent an ongoing burden for supply chain reporting, some ability to remain ahead of new substance restrictions can be achieved through full material declarations (FMD) specifically the IPC-1752A Class D Standard (the "Standard"), which was developed by the IPC - Association Connecting Electronic Industries. What is important to the supply chain is access to user-friendly, easily accessible or free, fully supported tools that allow suppliers to create and modify XML (Extensible Markup Language) files as specified in the Standard. Some tools will provide enhancements that validate required data entry and provide real-time interactive messages to facilitate the resolution of errors. In addition, validation and auto-population of substance CAS (Chemical Abstract Service) numbers, and Class D weight rollup validation ensure greater success in the acceptance of the declarations in customer systems that automate data gathering and reporting. A good tool should support importing existing IPC-1752A files for editing; this capability reduces the effort to update older declarations and greatly benefits suppliers of a family of products with similar composition. One of the problems with FMDs is the use of "wildcard" non-CAS numbers based on a declarable substance list (DSL). While the substances in different company's lists tend to have some overlap, no two DSL’s are the same. We provide an understanding of the commonality and differences between representative DSLs, and the ability to configure how much of a non-DSL substance percent is allowed. Case studies are discussed to show how supplier compliance data, can be automatically loaded into the customer's enterprise compliance system. Finally, we briefly discuss future enhancements and other developments like Once an Article, Always an Article (O5A) that will continue to require IPC standards and supporting tools to evolve.
Technical Library | 2019-04-24 20:06:51.0
Choosing an outsourced manufacturing partner that is perfect for a new product and close to your design team is quite different to choosing a partner that can manufacture that same product in volume in lower cost locations and fulfill globally. This is where the Gateway model comes into its own. Most large EMS have structured their organizations to leverage proximity to OEM design teams in high cost regions while providing the benefits of low cost regions for volume manufacturing. The "Gateway" facility in higher cost regions provides design engineering, supply chain design, prototype, and NPI services. The goal of the Gateway is to develop an effective build recipe that can then be effectively and seamlessly transferred to one or more volume manufacturing facility that offers lower costs and direct fulfillment to consumers.We will present a case study that highlights the value of this model and that shows some of the key elements that allow for seamless transitions from plant to plant. The Gateway model is an essential element to a successful global manufacturing model and helps ensure that products are made in the right geography.
Technical Library | 2015-03-19 20:33:34.0
Silicon is arguably the best electronic material, but it is not a good optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS) shows promising potential as a new kind of optoelectronic material. Most significantly, hydrogenation converts the intrinsic BS, a strongly indirect semiconductor, into a direct-gap semiconductor with a widely tunable band gap. At low hydrogen concentrations, four ground states of single- and double sided hydrogenated BS are characterized by dipole-allowed direct (or quasidirect) band gaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-sided hydrogenated BS structures exhibit direct (or quasidirect) band gaps in the color range of red, green, and blue, affording white light-emitting diodes. Our findings open opportunities to search for new silicon-based light-absorption and light-emitting materials for earth-abundant, high efficiency, optoelectronic applications.Originally published by the American Physical Society
Technical Library | 2015-06-18 12:42:57.0
In the recent past, the Light Emitting Diode (LED) was hailed as the new energy efficient light source that would never have to be replaced. There were claims of 50,000+ hrs lifetime for the humble LED. That story has changed over the last few years as the number and diversity of the LED based products has increased. This is not to say that the original evidence was incorrect, but the initial enthusiastic estimates from the labs did not match the ultimate test, customers. As a result of poor quality products affecting the overall opinion of LED based products, it is critical that manufacturers can be confident in the quality of their product. In current times we want to have products certified, checked and ensure that we have the best quality. For the purposes of this paper we will look at one aspect of LED product, and this is the Lumen maintenance and estimated lifetime. The method described here does not seek to replace using high quality rating labs, but hopefully will allow the manufacturer to know with confidence that their prototype product, upon going to certification labs will be of a high enough quality that no expensive re-designs are required.
