Apr 06, 2017 | Wim Bogaerts, Pieter Dumon, Martin Fiers; Luceda Photonics, Jeff Miller; Mentor Graphics
Silicon photonics is an IC technology where data is transferred using light that is routed on the chip using optical waveguides (Figure 1). Silicon photonics is best known as a method to solve problems with high input/output bandwidth applications. For example, because of ever-growing bandwidth requirements in datacenters, the optical transmit and receive heads are being placed closer and closer to the board and the IC. But, designers also apply this technology to biosensors, medical diagnostics, and environmental monitoring. Regardless of the application, photonic ICs always need integration to electronic circuits and this results in unique challenges....
Publisher: Mentor Graphics
Mar 30, 2017 | Bob Wettermann, BEST Inc. MIT
There are multiple methods, each with its associated benefits for given applications, for printing either solder paste or paste flux for BGA rework. Each of these methods is best-suited for a given situation, board layout and skill level of operators performing the BGA rework. This discussion will layout the various methods and present the specific circumstances for which the specific technique is most wellsuited. In addition, the pluses and minuses for each of the approaches will be discussed in detail....
Publisher: BEST Inc.
BEST offers professional rework, repair and prototype builds of PCBs. Our experienced instructors teach professional soldering classes as we are an IPC certified training center.
Rolling Meadows, Illinois, USA
Mar 22, 2017 | Tony Lentz
Water soluble lead-free solder paste is widely used in today’s SMT processes, but the industry is slowly moving away from water soluble solder pastes in favor of no-clean solder pastes. This shift in usage of solder paste is driven by an effort to eliminate the water wash process. Some components cannot tolerate water wash and elimination of water washing streamlines the SMT process. Despite this shift, certain applications lend themselves to the use of water soluble solder paste.
This paper details the research and development of a new water soluble lead-free solder paste which improves on the performance characteristics of existing technologies....
Publisher: FCT ASSEMBLY, INC.
Mar 15, 2017 | Randy Flinders
In 2012, The European Directive on Reduction of Hazardous Substances was recast. The new version of the directive now requires products to be adequately validated as RoHS compliant in order to be eligible for CE marking and access to the EU market (...)
This paper starts by reviewing the evolution of the RoHS directive and how it has evolved. It then moves on to cover the requirements and scope of the directive, as well as which standards are used to demonstrate compliance, and how those standards must be referenced in internal company quality processes....
Publisher: GreenSoft Technology, Inc.
GreenSoft Technology is a leading provider of environmental compliance content management tools, software and services for the global electronics industry for RoHS-2, REACH, Conflict Minerals and other regulations.
Pasadena, California, USA
Mar 09, 2017 | Jari Suikkola, Toni Björninen, Mahmoud Mosallaei, Timo Kankkunen, Pekka Iso-Ketola, Leena Ukkonen, Jukka Vanhala & Matti Mäntysalo
This article focuses on the fabrication and characterization of stretchable interconnects for wearable electronics applications. Interconnects were screen-printed with a stretchable silver-polymer composite ink on 50-μm thick thermoplastic polyurethane. The initial sheet resistances of the manufactured interconnects were an average of 36.2 mΩ/◽, and half the manufactured samples withstood single strains of up to 74%. The strain proportionality of resistance is discussed, and a regression model is introduced. Cycling strain increased resistance. However, the resistances here were almost fully reversible, and this recovery was time-dependent. Normalized resistances to 10%, 15%, and 20% cyclic strains stabilized at 1.3, 1.4, and 1.7. We also tested the validity of our model for radio-frequency applications through characterization of a stretchable radio-frequency identification tag....
Publisher: Tampere University of Technology
Mar 02, 2017 | Alexis Peschot, Chuang Qian, Tsu-Jae King Liu
The need for more energy-efficient solid-state switches beyond complementary metal-oxide-semiconductor (CMOS) transistors has become a major concern as the power consumption of electronic integrated circuits (ICs) steadily increases with technology scaling. Nano-Electro-Mechanical (NEM) relays control current flow by nanometer-scale motion to make or break physical contact between electrodes, and offer advantages over transistors for low-power digital logic applications: virtually zero leakage current for negligible static power consumption; the ability to operate with very small voltage signals for low dynamic power consumption; and robustness against harsh environments such as extreme temperatures. Therefore, NEM logic switches (relays) have been investigated by several research groups during the past decade. Circuit simulations calibrated to experimental data indicate that scaled relay technology can overcome the energy-efficiency limit of CMOS technology.
This paper reviews recent progress toward this goal, providing an overview of the different relay designs and experimental results achieved by various research groups, as well as of relay-based IC design principles. Remaining challenges for realizing the promise of nano-mechanical computing, and ongoing efforts to address these, are discussed....
Publisher: EECS at University of California
Feb 28, 2017 | Claus Würtz Nielsen Nokia Mobile Phones R&D
During the last 5 years mobile phones and other portable consumer electronics have been extremely popular and spread all over the world in different climate zones in very high volumes. At the same time the mobile phone terminal for many people has become a necessity that is brought with them in any activity they practice. These changes in user behavior have heavily changed the impact on handheld terminals from moisture, sweat, corrosive atmospheres and mechanical drop. As a result of this the requirement to solder joint reliability, corrosion stability and wear resistance are heavily increasing to keep a high reliability of the terminal.
Immersion Ni/Au has been the overall dominant surface finish on Printed Wiring Boards (PWB's) for the last 10 years, but a paradigm shift to avoid use of this thin and porous surface finish is ongoing nowadays because it can’t address these challenges in a satisfactory way.
In today's handheld terminals, Organic Solder Preservative (OSP) has replaced Immersion Ni/Au on solder pads. Carbon surface finish for Key- and spring contact-pads, combined with the right concept design can make use of Immersion Ni/Au unnecessary in the near future. The result will be higher reliability with less expensive and simpler processes.
This paper will discuss the various considerations for choice of surface finish and results from the feasibility studies performed....
Publisher: Nokia Corporation
Feb 23, 2017 | PTC
Managing the environmental performance of products is an increasingly complicated challenge for manufacturers today. These companies face a complex tangle of requirements and mandates from regulators, consumers and customers to manage the toxicity, recycleability and overall environmental impact of their products. Not only have governments, business-to-business customers and consumers demonstrated a clear preference for better environmentally performing and "greener" brands, but investors are now pressuring manufacturers, as well. For example, the Dow Jones Sustainability Index identifies and tracks leading sustainability-driven companies around the world.
This paper focuses on the challenges companies face and the best practices they can employ when collecting substance, material and compliance data from their suppliers and supply chain....
Feb 16, 2017 | Thomas Sanders, Sivasubramanian Thirugnanasambandam and John Evans, Ph.D., Michael Bozack, Ph.D., Jeff Suhling, Ph.D. - Auburn University, Wayne Johnson, Ph.D. - Tennessee Tech University
This experiment considers the reliability of a variety of different electronic components and evaluates them on 0.200” power computing printed circuit boards with OSP. Single-sided assemblies were built separately for the Top-side and Bottom-side of the boards. This data is for boards on the FR4-06 substrate.
This paper was originally published by SMTA in the Proceedings of SMTA International....
Publisher: Auburn University
Feb 09, 2017 | Eric Bastow
The SMT assembly world, especially within the commercial electronics realm, is dominated by no-clean solder paste technology. A solder paste flux residue that does not require removal is very attractive in a competitive world where every penny of assembly cost counts. One important aspect of the reliability of assembled devices is the nature of the no-clean solder paste flux residue. Most people in this field understand the importance of having a process that renders the solder paste flux residue as benign and inert as possible, thereby ensuring electrical reliability.
But, of all the factors that play into the electrical reliability of the solder paste flux residue, is there any impact made by the age of the solder paste and how it was stored? This paper uses J-STD-004B SIR (Surface Insulation Resistance) testing to examine this question....
Publisher: Indium Corporation