Emerald | Circuit World

Putting 3D interconnection technologies into perspective from chip to system

Joseph Fjelstad — 2012-02-03 00:00:00.0

Abstract

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 been widened, paved and branched by all who have followed them. Granted that the branches have led to new high-worth discoveries but acknowledging the past and taking instruction from it is important, even necessary, to assure that future developments do not continually “reinvent the wheel”. Originality/value – The paper traces, in brief fashion, the history of 3D interconnections providing examples of solutions which predate some of the current generation solutions which appear, in some cases, quite similar to those developed or proposed nearly half century ago. Knowing the past is vital to understanding and shaping the future.

The use of ultrasound to enable low temperature electroless plating

Andrew J. Cobley, Veronica Saez — 2012-02-03 00:00:00.0

Abstract

Purpose – Electroless plating is an important process in printed circuit board and electronics manufacturing but typically requires temperatures of 70-95°C to give a suitable deposition rate. This is becoming problematic in industry due to the rising price of energy and is a major contribution to production costs. Previous studies have noted beneficial effects of ultrasonic irradiation upon electroless plating processes and it has been reported that sonication can increase the plating rate and produce changes to the chemical and physical properties of the deposited coating. The purpose of this paper is to reduce the operating temperature of an electroless nickel bath by introducing ultrasound to the process. Design/methodology/approach – The deposition rate of an electroless nickel solution was determined by two techniques. In the first method, test coupons were plated in an electroless nickel solution at temperatures ranging from 50-90°C and the plating rate was calculated by weight gain. In the second approach the mixed potential (and hence the current density at the mixed potential) was determined by electrochemical analysis of the anodic and cathodic reactions. In both cases the plating rate was found with and without the application of an ultrasonic field (20?kHz). The electroless nickel deposits obtained in the plating tests were also analysed to determine the phosphorus content, microhardness and brightness. Findings – The plating rates under ultrasonic agitation were always higher than under “silent” conditions. Most importantly, considering the objectives of this study, the deposition rate under sonication at 70°C was significantly higher than that found with mechanical agitation at 90°C. In addition, the results indicated that the deposits produced in an ultrasonic field had consistently lower phosphorus content, higher microhardness and were brighter than those prepared in an electroless nickel bath that was not sonicated. Originality/value – Although previous work has been performed on the effect of ultrasound on electroless plating, all these studies have been carried out at the normal operating temperature of the electroless process. In this paper, ultrasound has been applied at temperatures well below those normally used in electroless nickel deposition to determine whether sonication can enable low temperature electroless plating.

Recovery of copper from PCB manufacturing effluent using chitin and chitosan

Martin Goosey, Rod Kellner — 2012-02-03 00:00:00.0

Abstract

Purpose – The purpose of this paper is to investigate the potential for using chitin and chitosan sustainable materials to absorb copper from PCB manufacturing effluent and to report the results of an initial feasibility study aimed at demonstrating proof of concept. Design/methodology/approach – Crab shells and prawn shells, both waste products of the seafood industry, as well as chitosan, were evaluated as potential absorbents for recovering copper present at low levels in the manufacturing effluent produced in a UK-based PCB manufacturing facility. Various conditions were investigated and efforts were also made to recover absorbed copper via a regeneration process that enabled the metal to be electroplated from solution. Findings – Although only a short feasibility study, conditions were found that enabled copper to be absorbed by the ground crab shells and chitosan and then subsequently recovered by electrowinning to produce the metal. Research limitations/implications – Although successful as a feasibility study, the experimental work highlighted the large number of variables that need to be investigated and optimised in order to obtain the most efficient copper capture and recovery. Further work needs to be carried out to determine these optimum conditions and to investigate the potential for recovery of other metals from a wider range of solutions. Originality/value – The paper details how individual treatment technologies can be combined to enable a much more sustainable approach to PCB manufacturing which offers the benefits of reduced effluent metal levels, metal recovery and a novel use for another sector's waste products.

Advanced surface protection for improved reliability PCB systems (ASPIS)

2012-02-03 00:00:00.0

Abstract

Purpose – The purpose of this paper is to detail progress on the European Commission supported FP7 ASPIS project that is undertaking a multi-faceted approach to develop novel and improved nickel-gold (ENIG) solderable finish chemistries and processes in order to overcome issues such as “black pad” that are known to cause reliability issues. Design/methodology/approach – The ASPIS project has four key and discrete approaches; research into “black pad” formation mechanisms, development of new aqueous chemical deposition methods, formulation of new processes based on ionic liquids and the development of prognostic screening tools to enable early prediction of reliability issues. Findings – Key factors influencing “black pad” formation include immersion gold bath pH value, concentration of citrate and thickness of the immersion gold layer. In addition, copper substrate preparation is also important. Work to develop new metal deposition processes using ionic liquids has also been demonstrated and may provide a viable alternative to more conventional aqueous based chemistries, thereby enabling some of the conditions that lead to “black pad” to be avoided. Research limitations/implications – This paper summarises the work carried out in the first year of a three-year project and so the outputs to date are relatively limited. The project is continuing for another two years, when further progress will be made. It is hoped to report this progress in a future update paper. Originality/value – The ASPIS project has undertaken multiple approaches to the development of new high reliability nickel gold finishes and this combination of approaches should offer synergies over more discrete traditional methodologies. As well as undertaking a detailed analysis of the mechanisms causing reliability problems, radical new formulation and prognostic approaches are also being developed.

A multi-electrode array (MEA) biochip with excimer laser-produced micro-well features

2012-02-03 00:00:00.0

Abstract

Purpose – The purpose of this paper is to highlight a novel manufacturing process for a biochip with a multi-electrode array (MEA) that is specifically designed for use in characterising cardio-active substances and to demonstrate a novel proposed solution prototype that has been constructed to meet the needs of end-users. Design/methodology/approach – Practical problems encountered with conventional MEA biochips are described and a novel biochip design to tackle these problems is presented. The manufacturing approach used to produce the prototypes of that design is described and depicted. Findings – The novel prototype MEA biochips were successfully manufactured using conventional electronics manufacturing approaches. Prototypes demonstrated limited successes in the early stages of testing. Further revisions of the feature geometry are required to implement an alternative MEA biochip that is suitably reliable. Research limitations/implications – Basic photolithography techniques have been used to construct a base substrate for proof-of-principle studies. Increased sophistication in manufacturing stages is required in future iterations of the proposed concept. Originality/value – This paper introduces a problem encountered by MEA system adopters that requires a suitable solution. The scale up of an electronics manufacturing process-based solution to the problems described holds much promise for the screening of new chemical entities.

Polar launches Speedflex HDI flex-rigid and high-density interconnect stackup design and documentation system

2012-02-03 00:00:00.0

International diary

2012-02-03 00:00:00.0

Susonence – a new multi-partner project developing advanced sonochemical processes to reduce chemical usage and decrease waste in the PCB and metal finishing industries

2012-02-03 00:00:00.0

RUWEL becomes a part of the world’s largest PCB manufacturer

2012-02-03 00:00:00.0

Latest BPA report on flex and flex-rigid PCB markets

2012-02-03 00:00:00.0

Reflections from a leader – IPC President and CEO Denny McGuirk Final IPC interview

2012-02-03 00:00:00.0

Institute of Circuit Technology Hayling Island Evening Seminar, 7 September 2011

2012-02-03 00:00:00.0

IeMRC 6th Annual Conference, Loughborough University, September 21 2011

2012-02-03 00:00:00.0

EIPC Autumn Conference, Basle, Switzerland, 13-14 October 2011

2012-02-03 00:00:00.0

Editorial

2012-02-03 00:00:00.0

Gareth Brown to join Ventec-Europe Limited

2012-02-03 00:00:00.0