Roslin, United Kingdom
Roslin, United Kingdom

Time filter

Source Type

Millar S.,Heriot - Watt University | Desmulliez M.P.Y.,Heriot - Watt University | McCracken S.,MCS Ltd
Microsystem Technologies | Year: 2011

This paper presents the limitations of the helium leak test when applied to typical MEMS packages. A novel closed-form expression is presented which allows the determination of the minimum cavity volume package that can be accurately tested using the helium leak test method in conjunction with a standard gross leak test. This expression can be used to find optimum test parameters for packages with cavity volumes greater than 2.6 × 10-3 cm 3. Hermeticity testing using FTIR and Raman spectroscopy are considered as potential methods to overcome the limitations of the helium leak test method. © Springer-Verlag 2010.


Costello S.,Heriot - Watt University | Costello S.,MCS Ltd. | Desmulliez M.P.Y.,Heriot - Watt University | McCracken S.,MCS Ltd. | And 4 more authors.
IEEE Transactions on Semiconductor Manufacturing | Year: 2013

The design, fabrication, and characterization of a piezoresistive membrane deflection test structure for the electrical evaluation of hermeticity in low cavity volume packages is discussed. This test structure uses the zero-level silicon cap as a deflecting membrane to electrically monitor changes in package cavity pressure over time. The hermeticity of the package can then be determined in real-time and low leak rates can be measured using a pressurization stage, which also accelerates the test. The minimum detectable leak rate of the test structure without acceleration has been measured at $6.9×,10 -12 atm cm3 s-1, which is two orders of magnitude lower than the limit of a traditional helium fine leak test. © 1988-2012 IEEE.


Millar S.,Heriot - Watt University | Desmulliez M.P.Y.,Heriot - Watt University | Cargill S.,Heriot - Watt University | McCracken S.,MCS Ltd.
Electronics System Integration Technology Conference, ESTC 2010 - Proceedings | Year: 2010

New leak detection strategies are required for MEMS packages as traditional methods are not suited due to the small size of the cavities involved. This paper presents the design, fabrication and calibration procedure for three in-situ test structures intended to monitor electrically the hermeticity of packages. The calibration results of a micro-Pirani test structure show that this test structure can be used to monitor the ambient pressure of vacuum packaged MEMS. Using a pressured tracer gas to accelerate the test, the micro-Pirani test structure can detect leak rates down to 10-15 atm.cm3.s-1.


Millar S.,Heriot - Watt University | Millar S.,MCS Ltd. | Desmulliez M.P.Y.,Heriot - Watt University | McCracken S.,MCS Ltd.
Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS, DTIP 2010 | Year: 2010

This paper presents the limitations of the helium leak test when applied to typical MEMS packages. Hermeticity testing using FTIR and Raman spectroscopy are investigated with a view to overcoming the limitations of the helium leak test method. Hermeticity testing using FTIR is successful demonstrated for low cavity volume MEMS and glass packaged devices. Raman spectroscopy also improves on these limitations and can be considered to determine leak rates caused by outgassing or permeation through package materials. © 2010 EDA Publishing/DTIP.


Costello S.,Heriot - Watt University | Costello S.,MCS Ltd. | Desmulliez M.P.Y.,Heriot - Watt University | McCracken S.,MCS Ltd.
IEEE Transactions on Components, Packaging and Manufacturing Technology | Year: 2012

This paper presents a critical review of the traditional and newly proposed test methods used for the measurement of hermeticity in packages with very small cavity volumes. Closed-form expressions of the minimum and maximum true leak rates achievable are provided for the helium fine leak test method. These expressions are shown to provide practical guidelines for the accurate testing of hermeticity for ultrasmall packages. A portfolio of hermeticity test methods is also presented outlining the limitations and advantages of each method. © 2011 IEEE.


Costello S.,Heriot - Watt University | Desmulliez M.P.Y.,Heriot - Watt University | McCracken S.,MCS Ltd. | Lowrie C.,Heriot - Watt University | And 2 more authors.
IEEE International Conference on Microelectronic Test Structures | Year: 2012

This paper details the design, fabrication and characterisation of a piezoresistive membrane deflection test structure for the electrical evaluation of hermeticity in low cavity volume package. This test structure uses the 0-level silicon cap, defined in the MultiMEMS foundry service, as a deflecting membrane to electrically monitor changes in package cavity pressure over time. The hermeticity of the package can then be determined in real-time and low leak rates can be measured using a pressurisation stage, which also accelerates the test. The minimum detectable leak rate of the test structure without test acceleration is 6.9×10 12 atm.cm 3.s 1, which is two orders of magnitude lower than the limit of the traditional helium fine leak test method. © 2012 IEEE.


Jones T.D.A.,Heriot - Watt University | Flynn D.,Heriot - Watt University | Desmulliez M.P.Y.,Heriot - Watt University | Price D.,Merlin Circuit Technology Ltd. | And 5 more authors.
Circuit World | Year: 2016

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 Raas 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. © Emerald Group Publishing Limited.


Zuzaan P.,National University of Mongolia | Gansukh N.,MCS Corporation | Bolortuya D.,National University of Mongolia
X-Ray Spectrometry | Year: 2010

In this paper an analytical procedure for the determination of La, Ce, Pr and Nd in rare-earth ores is described. More than 5000 of powdered samples were prepared from the ores selected in various places of their deposit. The samples were analyzed by energy-dispersive X-ray fluorescence (EDXRF) with an Am-241 source for the radiation excitation of characteristic K-lines of the elements mentioned. The results were compared with the data of other methods and reference materials. The correlation of La-Ce, La-Pr, La-Nd, Ce-Pr, Ce-Nd and Pr-Nd elements pairs were determined. © 2009 John Wiley & Sons, Ltd.


Banneyake R.,MCS Inc. | Eltaher A.,MCS Inc. | Jukes P.,MCS Inc.
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2010

Ovalization of the cross-section of bends under in-plane bending (a.k.a. Brazier effect) is a known phenomenon caused by the longitudinal stress acting on the cross-section as the pipe bends. Besides its tendency to induce stresses in the bend above what is predicted using simple beam theory, excessive cross-section ovalization is particularly critical to subsea pipes, as it can lead to collapse of the pipe under external pressure. Also, being in a plastic regime may cause the bend material to ratchet and undergo excessive strains under cyclic operational loads, especially under high-pressure high-temperature (HPHT) conditions. Ovalization normally results in local increase of stresses and could lead to failure of the bend before the bend globally reaches its limiting capacity. The offshore industry standards and design codes address the impact of initial ovality in straight pipes, but their applicability to bends is not clear. Therefore, this paper presents an investigation into the increased tendency of thin-walled bends to ovalize, and the effect of bend cross-section ovalization on their stiffness and yielding and collapse limit states, with emphasis on offshore applications. Due to the lack of analytical solutions for the bend response taking into account cross-section ovalization, finite element analysis (FEA) is used in this study. Predictions of the bend models are compared with those of straight pipe models and predictions of models of the bend made of beam elements (with pipe section) are compared with those of models made of brick/shell elements. The increased tendency of thin-walled bends to ovalize compared to straight pipes is investigated (e.g. 100 times in the linear range), and the impact and significance of ovalization in bends are assessed (e.g., stress increase of the order of 35% has been observed in some example situations). Also discussed in the paper is the selection of proper element specifications in order to accurately capture the ovalization response while keeping the computational cost manageable. Recommendations as to how to account for ovalization effects are presented. This paper helps to gain a better understanding of the response of subsea thin-walled bends under in-plane bending and their comparatively high tendency to ovalize compared to straight pipe, and emphasizes the significance of local effects such as cross-section ovalization, the overlooking of which may result in a significant underestimation of involved stresses and strains. © 2010 by ASME.

Loading MCS Ltd collaborators
Loading MCS Ltd collaborators