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Article
Publication date: 1 August 2016

Thomas D.A. Jones, David Flynn, Marc P.Y. Desmulliez, Dennis Price, Matthew Beadel, Nadia Strusevich, Mayur Patel, Chris Bailey and Suzanne Costello

This study aims to understand the influence of megasonic (MS)-assisted agitation on printed circuit boards (PCBs) electroplated using copper (Cu) electrolyte solutions to improve…

Abstract

Purpose

This study aims to understand the influence of megasonic (MS)-assisted agitation on printed circuit boards (PCBs) electroplated using copper (Cu) electrolyte solutions to improve plating efficiencies through enhanced ion transportation.

Design/methodology/approach

The impact of MS-assisted agitation on topographical properties of the electroplated surfaces was studied through a design of experiments by measuring surface roughness, which is characterised by values of the parameter Ra as measured by white light phase shifting interferometry and high-resolution scanning electron microscopy.

Findings

An increase in Ra from 400 to 760 nm after plating was recorded for an increase in acoustic power from 45 to 450 W. Roughening increased because of micro-bubble cavitation energy and was supported through direct imaging of the cavitation. Current thieving effect by the MS transducer induced low currents, leading to large Cu grain frosting and reduction in the board quality. Current thieving was negated in plating trials through specific placement of transducer. Wavy electroplated surfaces, due to surface acoustic waves, were also observed to reduce the uniformity of the deposit.

Research limitations/implications

The formation of unstable transient cavitation and variation of the topology of the Cu surface are unwanted phenomena. Further plating studies using MS agitation are needed, along with fundamental simulations, to determine how the effects can be reduced or prevented.

Practical implications

This study can help identify manufacturing settings required for high-quality MS-assisted plating and promote areas for further investigation, leading to the development of an MS plating manufacturing technique.

Originality/value

This study quantifies the topographical changes to a PCB surface in response to MS agitation and evidence for deposited Cu artefacts due to acoustic effects.

Details

Circuit World, vol. 42 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 13 February 2007

Andrew Richardson, Chris Bailey, Jean Marc Yanou, Norbert Dumas, Dongsheng Liu, Stoyan Stoyanov and Nadia Strusevich

To present key challenges associated with the evolution of system‐in‐package technologies and present technical work in reliability modeling and embedded test that contributes to…

Abstract

Purpose

To present key challenges associated with the evolution of system‐in‐package technologies and present technical work in reliability modeling and embedded test that contributes to these challenges.

Design/methodology/approach

Key challenges have been identified from the electronics and integrated MEMS industrial sectors. Solutions to optimising the reliability of a typical assembly process and reducing the cost of production test have been studied through simulation and modelling studies based on technology data released by NXP and in collaboration with EDA tool vendors Coventor and Flomerics.

Findings

Characterised models that deliver special and material dependent reliability data that can be used to optimize robustness of SiP assemblies together with results that indicate relative contributions of various structural variables. An initial analytical model for solder ball reliability and a solution for embedding a low cost test for a capacitive RF‐MEMS switch identified as an SiP component presenting a key test challenge.

Research limitations/implications

Results will contribute to the further development of NXP wafer level system‐in‐package technology. Limitations are that feedback on the implementation of recommendations and the physical characterisation of the embedded test solution.

Originality/value

Both the methodology and associated studies on the structural reliability of an industrial SiP technology are unique. The analytical model for solder ball life is new as is the embedded test solution for the RF‐MEMS switch.

Details

Circuit World, vol. 33 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

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