Joseph Fjelstad

3D PCB architecture for next generation high speed interconnections

Purpose – To review the challenges confronting the electronics interconnection industry as it transitions into the gigahertz frequency range and to describe novel prospective solutions designed to circumvent the problems by means of alternative interconnection architectures while remaining within the confines of the existing manufacturing infrastructure.Design/methodology/approach – The paper has been written in a manner so as to provide first a brief review of the history of interconnections as background reference, providing access and understanding to a broader readership of the significance of the area of investigation. From there, the paper describes the problems facing electronic circuit manufactures relative to the serious matter of assuring signal integrity of high speed interconnections. It then goes on to describe a general class of prospective solutions, which can be implemented through simple architectural changes in design and manufacture. Finally, the paper describes a prototype system which...

Environmentally friendly assembly of robust electronics without solder

Purpose – Tin‐lead solder has been the primary method for connecting electronic components to printed circuit boards since near the time of its inception. Over the last 60 years, solder has proven a viable assembly method over that time and there is a deep understanding of the technology won over years of practice. However, the European Union has banned the use of lead in electronic solder, based on the misguided assumption that lead in electronic solder represented a risk to human health. Aims to describe a new approach to manufacturing electronic assemblies without the use of solder.Design/methodology/approach – The paper discusses how the new era of lead‐free solder has resulted in a host of new problems for the electronics industry, many of which had not been experienced when elemental lead was included in the solder alloy.Findings – Electronics assembly technology literature is rife with articles and papers citing the problems or challenges of lead‐free assembly and proposing new or improved solution...

Flexible circuit materials

Purpose – To provide an overview of a process for making proper selection of base materials for use in the manufacture of flexible circuits.Design/methodology/approach – The paper provides an introductory review of the desirable attributes for flexible circuit substrates and includes a description of the attribute and its specific role and impact on the finished product.Findings – The paper highlights the importance of making informed materials choices in flexible circuit manufacture. Flexible circuits are an increasingly important member of the family of electronic interconnection technologies and are also the fastest growing. A variety of materials can be used for flexible circuit construction, however, the choice must be tempered by the manufacturing and assembly processes and the application of the finished product.Research limitations/implications – The paper provides a limited overview of the desirable properties of flexible circuit materials and is designed to provide initial background and guidanc...

Manufacture of an aluminum rigid‐flex circuit assembly without the use of solder

Purpose – The purpose of this paper is to describe a novel method for the manufacture of aluminum rigid‐flex circuit assemblies without the use of solder.Design/methodology/approach – The approach involves the use of an aluminum base material and the embedding of components, while avoiding the use of solder in the assembly process.Findings – The new methods and proposed structures address the key manufacturing problems that have vexed users for many years, while simultaneously addressing the challenge of thermal management. They also offer the advantage of enhanced reliability by avoiding the need for high temperatures used in soldering.Research limitations/implications – While examples of the process and its benefits have been demonstrated, further work is ongoing to expand applicability.Originality/value – The paper begins with an overview of previous work in this area and then moves on to what is currently being implemented via the new technology. A novel method is described for the creation of potenti...

Manufacture of high density interconnection substrates by co‐lamination of inner layers and programmed interconnection joining layers

While promising significant improvements in the cost and performance of electronic systems, the advent of new area array packaging concepts such as the BGA and newer area array CSPs has placed significant new demands on the substrates used in their interconnection. New methods such as build‐up multilayers and micro vias and co‐lamination of inner layers have been described and implemented by a number of different firms in an attempt to address this important issue. One such method employs simple double‐sided plated through hole flex circuits and the use of conductive pastes and bondplies to provide reliable electrical and mechanical connection between layers during a simple lamination cycle. The process, briefly described herein as a co‐laminated multilayer flex, is detailed in terms of both process steps and manufacturing flow. The structure of the interconnection substrate is also modeled and examined to determine its electrical performance potential according to electrical modeling software. Finally, detailed are the performance of the structure in reliability testing and an analysis of the expected design and performance advantages that might be obtained by such type constructions in combination with BGAs and area array CSPs.

Putting 3D interconnection technologies into perspective from chip to system

Purpose – The purpose of this paper is to provide a historical perspective and framework for appreciating the evolution of 3D interconnection technologies from past to present.Design/methodology/approach – A literature and patent search was performed to find the origins of 3D interconnections to find and credit work that was performed in the early electronics industry which presaged the development of the current generation 3D solutions.Findings – The origins of 3D interconnections have roots that date to the beginnings of electronic interconnections if the earlier solutions are viewed in proper perspective. For example, early telegraphy and telephony interconnections strung from pole to pole across large expanses of terrain were clearly 3D interconnections on a very macro scale but those solutions scaled down are not that dissimilar to what is being done today in some advanced interconnection technologies.Research limitations/implications – The pioneers of the electronics industry broke a trail which has...

Interconnection strategies for high‐density printed circuits – an overview

The drive to increase the functionality and performance of electronic products has resulted in the need to increase the density of every element of the electronics assembly from the silicon chip, which has relentlessly reduced in size, to the printed circuits used in their interconnection. Accompanying the reduction in feature sizes on IC chips has been an explosion in pin counts, especially in high‐end microprocessors. The challenge thus falls to the electronics interconnection and packaging industry to allow the pace to continue. Reviews strategies being either proposed or used to meet the challenge of high‐density interconnection at both chip package and next level substrate.