Thin film flexible electronics refer to a class of electronic devices built on flexible substrates. Examples includes printed Li batteries, Thin film flexible electronics refer to a class of electronic devices manufactured by multiple layering and scribing on flexible polymer substrates. Examples of such devices includes printed Li batteries, flexible photovoltaic cells and light emitting diodes. These devices are often mass manufactured by Roll-to-Roll processing (R2R). Whilst the basic technology is well established, the increasing demands on precision environmental protection and multi layering of devices means that in-process measurement of printed surface features is a critical bottle neck in terms of developing R2R as a process route. The purpose of the present paper is to review the current critical dimensional metrology needs in R2R manufacture and in particular to highlight the development of a new inprocess surface metrology system based on Multi-wavelength Polarizing Interferometry (MPI). The system is capable of measurement in real time, is environmentally robust and has nanometre resolution. The paper concludes by highlighting an example of the first trial implementation of the MPI on a production level R2R machine and discussed issues with quantification of film dimensions and associated signal processing
Film processing procedures by means of Roll-to-Roll (R2R) for barrier coatings can often result in PV barrier films being manufactured with significant quantities of defects, which results in lower efficiency and a short life span. In order to improve the process yield and product efficiency, it is desirable to develop an inspection system that can detect transparent barrier film defects in the production line during film processing. Off-line detection of defects in transparent PV barrier films is difficult and time consuming. Consequently, implementing an accurate in-situ defects inspection system in the production environment is even more challenging, since the requirements on positioning, fast measurement, long term stability and robustness against environmental disturbance are demanding. This paper reports on the development and deployment of two in-situ PV barrier films defect detection systems, one based on wavelength scanning interferometry (WSI) and the other on White Light Channeled Spectral Interferometry (WLCSI), and the integration into an R2R film processing line at the Centre for Process Innovation (CPI). The paper outlines the environmental vibration strategy for both systems, and the developed auto-focusing methodology for WSI. The systems have been tested and characterised and initial results compared to laboratory-based instrumentation are presented.
A comprehensive 3-dimensional measurement and characterization method for grinding tool topography was developed. A stylus instrument (SOMICRONIC, France) was used to measure the surface of a metal-bonded diamond grinding tool. The sampled data was input the software SurfStand developed by Centre for Precision Technology (CPT) for reconstruction and further characterization of the surface. Roughness parameters pertaining to the general surface and specific feature parameters relating to the grinding grits, such as height and angle peak curvature have been calculated. The methodology of measurement has been compared with that using an optical microscope. The comparison shows that the three-dimensional characterization has distinct advantages for grinding tool topography assessment. It is precise, convenient and comprehensive so it is suitable for precision measurement and analysis where an understanding of the grinding tool and its cutting ability are required.
Measurement system analysis guarantees the reliability of acquired data. Although much research has been performed
regarding variable measurement system and Gage R&R has been comprehensively employed across many companies,
there is relatively little attention that has been paid to binary measurement system, which is considered to be more
practical and efficient. Proportion of agreement is generally utilised to evaluate binary measurement system in the
traditional AIAG method. As a consequence, sample size should be more reasonably determined, in which process the
number of parts, appraisers, and trials are of key importance. However, this critical issue has not been profoundly
investigated as yet. In the present study, the number of parts is determined through the plot of length of confidence
interval, and an alternative method is introduced to choose the number of appraisers and trials based on the majority
voting rule. This is considered to be more sensible than the prevalent rule, in which two appraisers and two trials are
usually chosen and an agreement is made only when the conclusions of both appraisers and trials are the same. In
addition, a data set is analysed using the proposed method, and the results indicate that it is more rational.
This paper proposes a novel philosophical approach using Wavelet and Radon Transform for addressing topographical features of surface from a PSI image. In this work, a combined technique using the Wavelet and Radon Transforms has been investigated and developed to achieve the forensic dissection of PSI image data. As a result, the isolated point-like features on a PSI image can be extracted using the wavelet transform with artifact free thresholding method, and the curve-like features on a PSI image can be identified using the Ridgelet Transform (Multi-Wavelet-Radon transform). Case studies are conducted using a series of femoral heads to demonstrate the application of using the new wavelet model in the assessment PSI images of these surfaces.
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