Sony Mathew - Academia.edu (original) (raw)

Papers by Sony Mathew

Research paper thumbnail of Assessment of Solder-Dipping as a Tin Whisker Mitigation Strategy

Tin whiskers have been brought back into the spotlight due to the transition of the electronics i... more Tin whiskers have been brought back into the spotlight due to the transition of the electronics industry to lead-free solders. Many different tin whisker failure mitigation strategies are being evaluated by researchers. This paper investigates the technique of solder-dipping as a tin whisker mitigation strategy for tin-based lead-free finished surfaces used in electronic products. Tin finished Alloy 42 lead-frame parts are subjected to the solder-dip process. For this paper, the solders included eutectic tin-lead and tin-silver-copper. In addition, tin-bismuth (Sn-Bi) finished alloy 42 lead-frame parts are also examined to assess the effectiveness of the Sn-Bi finish in mitigating tin whisker growth. Parts under study are subjected to temperature cycling conditions to promote whisker formation. It is observed that whiskers are formed on all treatment surfaces, with the longest whiskers occurring on the pure tin-finished parts. The solder-dipped parts showed better mitigation of tin whiskers than the pure tin-finished parts.

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Research paper thumbnail of Prognostics Assessment of Aluminum Support Structure on a Printed Circuit Board

Journal of Electronic Packaging, 2006

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Research paper thumbnail of Virtual Remaining Life Assessment of Electronic Hardware Subjected to Shock and Random Vibration Life Cycle Loads

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Research paper thumbnail of Evaluation of pure tin plated copper alloy substrates for tin whiskers

Circuit World, 2009

Purpose – The purpose of this paper is to present the results from work on a project aimed at eva... more Purpose – The purpose of this paper is to present the results from work on a project aimed at evaluating six different copper alloy substrates coated with pure tin for tin whisker growth. The influence of intermetallic growth between the copper alloy substrate and the tin-plating on the growth of tin whiskers has been investigated. Design/methodology/approach – The experiment consisted

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Research paper thumbnail of Tin Whiskers: How to Mitigate and Manage the Risks

The selection of lead-free tin based surface finishes resulting from government regulation of lea... more The selection of lead-free tin based surface finishes resulting from government regulation of lead has reintroduced, into the spotlight, the reliability concern due to the possible formation of electrically conductive tin whiskers. This paper reviews risk mitigation studies including use of tin alloys, conformal coating, electroplating techniques, surface treatment, annealing, and use of under-layer material. This paper also discusses approaches

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Research paper thumbnail of Assessment of risk resulting from unattached tin whisker bridging

Circuit World, 2007

Purpose – This paper aims to present a methodology for estimating the risk of component level ele... more Purpose – This paper aims to present a methodology for estimating the risk of component level electrical bridging failures from unattached conductive (tin) whiskers. Design/methodology/approach – Based on experimental data an algorithm was developed and assessed by further experiments. The risk estimate is based on whisker parameters, generated from experiments over a period of time. A bridging failure risk is defined as the probability of a conductive whisker landing between two isolated electrical conductors. A probabilistic estimate for electrical bridging failure risk is achieved by randomly sampling distributions of conductive whisker length, deposition angle, and density for a defined electrical structure. A fine pitch quad flat package attached to a printed wiring board is used as test vehicle to verify the risk estimate. Findings – The estimated risk is found to be higher than planned in the experimental test. The lower experimentally determined risk was found to be the result of high contact resistance between the conductive whisker and the electrical conductors that form the unintended circuit. Contact resistance between the whisker and electrical conductors was found to mitigate the whisker shorting risk. Originality/value – This is the first attempt to quantify the risk failure due to unattached conductive whiskers in electronic products. A methodology for estimating electrical bridging risk due to unattached conductive whiskers is provided. Contact resistance of conductive whiskers is found to be a critical issue that may be mitigate failure risks.

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Research paper thumbnail of Tin whisker risk assessment

Circuit World, 2006

Purpose – To present a methodology, including the algorithms, to quantify the risk of failure fro... more Purpose – To present a methodology, including the algorithms, to quantify the risk of failure from tin whiskers and to present a dynamic risk trend based on the distribution of each of the whisker growth parameters, generated from experiments over a period of time. This paper also aims to demonstrate the practical application of the methodology developed. Design/methodology/approach – This paper has been written to provide a methodology to assess tin whisker risk due to fixed whiskers in electronic products. The risk assessment process has been detailed in the paper. To demonstrate the usefulness of the methodology, a tin whisker risk assessment was conducted for a printed circuit board (PCB) in operation. Findings – Based on the experimental tin whisker growth data it is observed that growth rates of mean length and average density decrease with time. Based on the risk assessment, it was estimated that for the common matte tin over copper finish, the failure risk for the circuit card assembly was 4 per cent over 20 years. It was recommended that, for this product, components with bright tin lead finish should not be used. It was also found that the effectiveness of the conformal coating on this PCB is limited by the relative risk of the components on the board. Originality/value – The paper provides a new methodology to assess fixed tin whisker risk in electronic products. The methodology provides a dynamic risk trend with time because the algorithm incorporates distributional data of whisker growth and the distributional data as a function of time. This type of assessment was lacking in the previous studies.

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Research paper thumbnail of Failure mechanisms based prognostics

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Research paper thumbnail of Anomaly detection in electronic products

Anomalous and intermittent behavior is a leading concern for electronics manufacturers of electro... more Anomalous and intermittent behavior is a leading concern for electronics manufacturers of electronic products. Yet it is often not possible to replicate such behavior, let alone determine the root cause of faults. This paper presents an approach to identify anomalous behavior using a simple Mahalanobis distance approach. A case study of experiments conducted on a field returned electronic product is presented.

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Research paper thumbnail of Assessment of Solder-Dipping as a Tin Whisker Mitigation Strategy

Tin whiskers have been brought back into the spotlight due to the transition of the electronics i... more Tin whiskers have been brought back into the spotlight due to the transition of the electronics industry to lead-free solders. Many different tin whisker failure mitigation strategies are being evaluated by researchers. This paper investigates the technique of solder-dipping as a tin whisker mitigation strategy for tin-based lead-free finished surfaces used in electronic products. Tin finished Alloy 42 lead-frame parts are subjected to the solder-dip process. For this paper, the solders included eutectic tin-lead and tin-silver-copper. In addition, tin-bismuth (Sn-Bi) finished alloy 42 lead-frame parts are also examined to assess the effectiveness of the Sn-Bi finish in mitigating tin whisker growth. Parts under study are subjected to temperature cycling conditions to promote whisker formation. It is observed that whiskers are formed on all treatment surfaces, with the longest whiskers occurring on the pure tin-finished parts. The solder-dipped parts showed better mitigation of tin whiskers than the pure tin-finished parts.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Prognostics Assessment of Aluminum Support Structure on a Printed Circuit Board

Journal of Electronic Packaging, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Virtual Remaining Life Assessment of Electronic Hardware Subjected to Shock and Random Vibration Life Cycle Loads

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Evaluation of pure tin plated copper alloy substrates for tin whiskers

Circuit World, 2009

Purpose – The purpose of this paper is to present the results from work on a project aimed at eva... more Purpose – The purpose of this paper is to present the results from work on a project aimed at evaluating six different copper alloy substrates coated with pure tin for tin whisker growth. The influence of intermetallic growth between the copper alloy substrate and the tin-plating on the growth of tin whiskers has been investigated. Design/methodology/approach – The experiment consisted

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Tin Whiskers: How to Mitigate and Manage the Risks

The selection of lead-free tin based surface finishes resulting from government regulation of lea... more The selection of lead-free tin based surface finishes resulting from government regulation of lead has reintroduced, into the spotlight, the reliability concern due to the possible formation of electrically conductive tin whiskers. This paper reviews risk mitigation studies including use of tin alloys, conformal coating, electroplating techniques, surface treatment, annealing, and use of under-layer material. This paper also discusses approaches

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Assessment of risk resulting from unattached tin whisker bridging

Circuit World, 2007

Purpose – This paper aims to present a methodology for estimating the risk of component level ele... more Purpose – This paper aims to present a methodology for estimating the risk of component level electrical bridging failures from unattached conductive (tin) whiskers. Design/methodology/approach – Based on experimental data an algorithm was developed and assessed by further experiments. The risk estimate is based on whisker parameters, generated from experiments over a period of time. A bridging failure risk is defined as the probability of a conductive whisker landing between two isolated electrical conductors. A probabilistic estimate for electrical bridging failure risk is achieved by randomly sampling distributions of conductive whisker length, deposition angle, and density for a defined electrical structure. A fine pitch quad flat package attached to a printed wiring board is used as test vehicle to verify the risk estimate. Findings – The estimated risk is found to be higher than planned in the experimental test. The lower experimentally determined risk was found to be the result of high contact resistance between the conductive whisker and the electrical conductors that form the unintended circuit. Contact resistance between the whisker and electrical conductors was found to mitigate the whisker shorting risk. Originality/value – This is the first attempt to quantify the risk failure due to unattached conductive whiskers in electronic products. A methodology for estimating electrical bridging risk due to unattached conductive whiskers is provided. Contact resistance of conductive whiskers is found to be a critical issue that may be mitigate failure risks.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Tin whisker risk assessment

Circuit World, 2006

Purpose – To present a methodology, including the algorithms, to quantify the risk of failure fro... more Purpose – To present a methodology, including the algorithms, to quantify the risk of failure from tin whiskers and to present a dynamic risk trend based on the distribution of each of the whisker growth parameters, generated from experiments over a period of time. This paper also aims to demonstrate the practical application of the methodology developed. Design/methodology/approach – This paper has been written to provide a methodology to assess tin whisker risk due to fixed whiskers in electronic products. The risk assessment process has been detailed in the paper. To demonstrate the usefulness of the methodology, a tin whisker risk assessment was conducted for a printed circuit board (PCB) in operation. Findings – Based on the experimental tin whisker growth data it is observed that growth rates of mean length and average density decrease with time. Based on the risk assessment, it was estimated that for the common matte tin over copper finish, the failure risk for the circuit card assembly was 4 per cent over 20 years. It was recommended that, for this product, components with bright tin lead finish should not be used. It was also found that the effectiveness of the conformal coating on this PCB is limited by the relative risk of the components on the board. Originality/value – The paper provides a new methodology to assess fixed tin whisker risk in electronic products. The methodology provides a dynamic risk trend with time because the algorithm incorporates distributional data of whisker growth and the distributional data as a function of time. This type of assessment was lacking in the previous studies.

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Research paper thumbnail of Failure mechanisms based prognostics

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Anomaly detection in electronic products

Anomalous and intermittent behavior is a leading concern for electronics manufacturers of electro... more Anomalous and intermittent behavior is a leading concern for electronics manufacturers of electronic products. Yet it is often not possible to replicate such behavior, let alone determine the root cause of faults. This paper presents an approach to identify anomalous behavior using a simple Mahalanobis distance approach. A case study of experiments conducted on a field returned electronic product is presented.

Bookmarks Related papers MentionsView impact