Technical Library | 2020-11-10 15:43:25.0
Flexible hybrid electronics (FHE) interface rigid electronic components with flexible sensors, circuits, and substrates. This paper reports the reliability improvement of a FHE Human Performance Monitor (HPM), designed to monitor electrocardiography (ECG) signals.
Technical Library | 2023-03-13 19:06:53.0
Purpose – There has been increasing interest in the development of printable electronics to meet the growing demand for low-cost, large-area, miniaturized, flexible and lightweight devices. The purpose of this paper is to discuss the electronic application of novel printable materials. Design/methodology/approach – The paper addresses the utilization of polymer nanocomposites as it relates to printable and flexible technology for electronic packaging. Printable technology such as screen-printing, ink-jet printing, and microcontact printing provides a fully additive, non-contacting deposition method that is suitable for flexible production.
Technical Library | 2019-05-01 23:18:27.0
Moisture can accelerate various failure mechanisms in printed circuit board assemblies. Moisture can be initially present in the epoxy glass prepreg, absorbed during the wet processes in printed circuit board manufacturing, or diffuse into the printed circuit board during storage. Moisture can reside in the resin, resin/glass interfaces, and micro-cracks or voids due to defects. Higher reflow temperatures associated with lead-free processing increase the vapor pressure, which can lead to higher amounts of moisture uptake compared to eutectic tin-lead reflow processes. In addition to cohesive or adhesive failures within the printed circuit board that lead to cracking and delamination, moisture can also lead to the creation of low impedance paths due to metal migration, interfacial degradation resulting in conductive filament formation, and changes in dimensional stability. Studies have shown that moisture can also reduce the glass-transition temperature and increase the dielectric constant, leading to a reduction in circuit switching speeds and an increase in propagation delay times. This paper provides an overview of printed circuit board fabrication, followed by a brief discussion of moisture diffusion processes, governing models, and dependent variables. We then present guidelines for printed circuit board handling and storage during various stages of production and fabrication so as to mitigate moisture-induced failures.
Technical Library | 2019-09-19 00:28:48.0
The symbiotic relationship between solder masks and selective finishes is not new. The soldermask application is one of the key considerations to ensure a successful application of a selective finish. The selective finish is the final chemical step of the PCB manufacturing process, this is when the panels are at their most valuable and are unfortunately not re-workable. Imperfections are not tolerated, even if they are wholly cosmetic. Quality issues often manifest themselves in the form of a 'ping pong' conversation between the fabricators, the soldermask suppliers and the selective finish suppliers. Without tangible evidence these discussions are difficult to resolve and the selective finish process is usually regarded as responsible. This paper will focus on the chemical characteristics and use them to predict or identify potential issues before they occur rather than specifically name 'critical' soldermasks. It is also the intention of this paper to address the potential of a soldermask to react to common yield hiking practices like UV bumping and oven curing. It is hoped that this awareness will help fabricators to ensure maximum yields by asking the right questions. 'Critical’ soldermasks impact all selective finishes. In this paper, practical experience using immersion tin will be used to highlight the relationship between 'critical' soldermasks and some of the issues seen in the field. The paper will include a novel approach to identify re-deposited volatiles after the reflow.
Technical Library | 2016-08-04 10:34:35.0
With the onset of 1900’s, the novelty of printed circuits boards got started with a profound concept of constructing an electrical path on an isolated surface of a board. The initial trend of printed circuit board got into a vain to develop and upgrade the radios and gramophones. Gradually the notion of ‘Through Hole Technique’ came into picture to produce a double sided PCB. In mid 1990’s the idea of auto assembly process was introduced by PCB Manufacturer USA. This was a point of modern touch to enhance the fabrication process with automated soldering technique. The research and development picked up a pace for end to end electronic solutions for defense and US army.
Technical Library | 2013-02-22 19:55:36.0
Productivity. Innovation. Time to market. Day to day, year over year, businesses are forced to make critical R.O.I.—related decisions that impact the future and the bottom line—some of them reactionary, some forecasted. For a growing number of electronics manufacturers, many of those decisions revolve around whether a function should be performed by an outside contractor or kept in-house. But for many companies in the RF/microwave industry, this decision is often concerned with continuing to employ an outside PCB fabricator for prototype PCBs, or to make a $10,000 to $100,000 investment in an inhouse, rapid PCB prototyping machine that may represent a key competitive advantage.
Technical Library | 2013-03-07 18:25:36.0
The market for high-layer-count printed circuit boards (PCB) containing blind and buried vias was once relatively small, and focused on specialized applications in the military and high end computing. The demand for these types of PCBs today is being driven by an increasing number of commercial applications in the telecommunications and semiconductor test market segments. These applications typically require high-aspect-ratio plated-through-holes (PTHs) and blind and buried vias in order to meet the applications interconnect density requirements. Blind and buried vias and high aspect ratio PTHs continue to present manufacturing challenges and frequently are the limiting features to achieving high fabrication yield... First published in the 2012 IPC APEX EXPO technical conference proceedings
Technical Library | 2014-11-18 23:59:30.0
Performance degradation of packaging material is an important reason for the lifetime reduction of LED. In order to understanding the failure behavior of packaging material, silicone and phosphor were chosen to fabricate LED samples within which an aging test at 125℃ was performed. The result of online luminance measurement showed that LED samples with both silicone and phosphor had the highest luminance decay rate among all test samples because the carbonization of silicone and the consequent outgassing reduced the luminance quickly. The result of the luminance variance with test time was analyzed and an exponential decay model was developed with which the lifetime of LED under high temperature could be estimated.
Technical Library | 2015-06-22 16:39:47.0
Surface finishing is an integral part of any PCB fabrication. It is generally applied to exposed Cu connectors and conductors on the board. Surface finishing has numerous important functions. It serves as a protective layer for the Cu connectors during storage. The surface finish helps minimize or reduce tarnish of the Cu substrate. Additionally, since it is the layer that comes into contact with other components during assembly, it ensures good solderability between the PCB and the component during assembly. Furthermore after assembly, the finish helps prolong the integrity of the solder joint during use. A general review of common PCB surface finishes is presented. The advantages and disadvantages of each are discussed and compared.
Technical Library | 2020-02-19 23:12:55.0
Silver nanowires (Ag NWs) possess excellent optoelectronic properties, which have led to many technology-focused applications of transparent and flexible electronics. Many of these applications require patterning of Ag NWs into desired shapes, for which mask-based and printing-based techniques have been developed and widely used. However, there are still several limitations associated to these techniques. These limitations, such as complicated patterning procedures, limited patterning area, and compromised optical transparency, hamper the efficient fabrication of high-performance Ag NW patterns. Here, we propose a coat-and-print approach for effectively patterning Ag NWs.
Integrated Microwave Packaging Antennas and Circuits Technology (IMPACT) Lab
