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Surface modification of SU-8 for metal/SU-8 adhesion using RF plasma treatment for application in thermopile detectors
Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. (Detector and Photonics)
Mid Sweden University, Faculty of Science, Technology and Media, Department of Electronics Design. (Detector and Photonics)
Helmholtz Zentrum, Inst Methods & Instrumentat Synchrotron Radiat Re, Berlin, Germany.
Uppsala Univ, Dept Chem, Angstrom Lab, Uppsala, Sweden.
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2015 (English)In: Materials Research Express, ISSN 2053-1591, Vol. 2, no 8, article id 086501Article in journal (Refereed) Published
Abstract [en]

This article reports on plasma treatment of SU-8 epoxy in order to enhance adhesive strength for metals. Its samples were fabricated on standard silicon wafers and treated with (O2 & Ar) RF plasma at a power of 25W at a low pressure of (3×10-3 torr) for different time spans (10 sec – 70 sec). The sample surfaces were characterized in terms of contact angle, surface (roughness and chemistry) and using a tape test. During the contact angle measurement, it was observed that the contact angle was reduced from 73° to 5° (almost wet) and 23° for (O2 & Ar) treated samples, respectively. The RMS surface roughness was significantly increased by 21.5% and 37.2% for (O2 & Ar) treatment, respectively. A pattern of metal squares was formed on the samples using photolithography for a tape test. An adhesive tape was applied to the samples and peeled off at 180o. The maximum adhesion results, more than 90%, were achieved for the O2-treated samples, whereas the Ar-treated samples showed no change. The XPS study shows the formation of new species in the O2-treated sample compared to the Ar-treated samples. The high adhesive results were due to the formation of hydrophilic groups and new O2 species in the O2-treated samples, which were absent in Ar-treated samples.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2015. Vol. 2, no 8, article id 086501
Keywords [en]
SU-8, contact angle, plasma treatment, surface modification, adhesion, tape test, theromocouples
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:miun:diva-26157DOI: 10.1088/2053-1591/2/8/086501ISI: 000370037800017Scopus ID: 2-s2.0-84954539766Local ID: STCOAI: oai:DiVA.org:miun-26157DiVA, id: diva2:865444
Available from: 2015-10-28 Created: 2015-10-28 Last updated: 2018-10-15Bibliographically approved
In thesis
1. Design and Integration of Infrared Absorber Structures into Polymer Membranes based Thermal Detectors
Open this publication in new window or tab >>Design and Integration of Infrared Absorber Structures into Polymer Membranes based Thermal Detectors
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2015. p. 90
Series
Mid Sweden University licentiate thesis, ISSN 1652-8948 ; 118
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-26176 (URN)STC (Local ID)978-91-88025-20-3 (ISBN)STC (Archive number)STC (OAI)
Presentation
2015-09-17, O111, Holmgatan 10, Sundsvall, 10:00 (English)
Opponent
Supervisors
Available from: 2015-11-02 Created: 2015-10-30 Last updated: 2017-03-02Bibliographically approved
2. Thermal detector with integrated absorber structure for mid-IR gas detection
Open this publication in new window or tab >>Thermal detector with integrated absorber structure for mid-IR gas detection
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Measurement of the concentration of greenhouse gases, such as carbon dioxide(CO 2 ) and methane (CH 4 ), in the atmosphere has received significant attention in the last few decades. This work focusses on the development of high-performance thermopile detectors for use with the non-dispersive infrared (NDIR) measurements of such gases. The performance of the thermopile detectors could effectively be increased by selecting membrane materials with a low thermal conductivity value and an efficient infrared (IR) absorbing material and by selecting the materials with high Seebeck coefficient values. Graphite black paint can be used as a radiation absorber, as it has high absorption (80—93%) for a wide spectral range (2.5 μm — 20 μm). By using spray paint or a paint brush, the application of the absorber is simple and fast. However, the control over the processing process suffers with these simple methods. The thermal capacitance of the detector will rapidly increase due to uneven distribution and unknown thickness of the absorber, although the response of the thermopile detector will be maximum due to high absorption; however, the response time (τ th )for the detector will be longer.In order to improve the performance, IR absorbers have been designed to utilise the membrane (SU-8 epoxy) of the detector as an active part of the IR absorber. This utilisation of the SU-8 epoxy membrane will result in a maximum detector sensitivity and a minimum increase in both the thermal capacitance and thermal conductance of the thermopile detector. Absorber structures, based on SU-8 epoxy, with a narrow absorption band at 4.26 µm and a wider multi-layered absorption band at 3-6 µm, were designed, simulated, and fabricated, and their integration into the membrane of thermopile detectors have been presented. The response of the thermopile detector could also be increased by using materials with high Seebeck coefficient [1] values such as semiconductor materials, as they have higher Seebeckvalues compared to the metals. In the thesis, molybdenum disulfide (MoS 2 ) flakes were characterised, and Seebeck values were estimated through a measurement setup as a function of temperature difference (ΔT). The fabricated thermopile detectors were characterised, and the response time(τ th ) of a thermocouple with a multi-layered absorber structure has been estimated to be 21 ms. The detector has shown high responsivity value in the wavelength range of 3 µm – 4.5 µm, which is used for CO 2 and CH 4 detection. The thermopile detector was evaluated for CO 2 gas through a long-path-length NDIR platform. The results show that the evaluated thermopile could be used for the measurement of gas concentration down to levels of a few parts per million (ppm) by using the long-path-length NDIR platform.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University, 2018. p. 81
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 280
Keywords
Thermal detectors, Thermopile detectors, Infrared absorbers, SU-8 epoxy, Interferometric and Multi-layered absorber, Seebeck coefficient, Molybdenum di-sulfide
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-34616 (URN)978-91-88527-48-6 (ISBN)
Public defence
2018-05-21, L111, Sundsvall, 10:00 (English)
Opponent
Supervisors
Note

Personal Email to Author

shakeel.llm@gmail.com

Vid tidpunkten för disputationen var följande delarbeten opublicerade: delarbete 5 (inskickat), delarbete 7 (manuskript).

At the time of the doctoral defence the following papers were unpublished: paper 5 (submitted), paper 7 (manuscript).

Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2018-10-15Bibliographically approved

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Publisher's full textScopushttp://iopscience.iop.org/article/10.1088/2053-1591/2/8/086501/meta

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Ashraf, ShakeelMattsson, ClaesThungström, Göran

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