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A frequency selective surface for spatial filtering in the standardized Ultra-Wide Band (UWB) frequency range is proposed. A very large stop-band of 1.75–15.44 GHz has been obtained, with good polarization insensitivity and an angular stability of more than 60∘ and more than 50∘ in TE and TM incidence, respectively. Circuit models have been devised. The structure has been assessed by electromagnetic simulation and implemented on an FR4 substrate of 1.6 mm thickness, with an edge of the square-shaped unit cell of 15 mm. Tests in an anechoic chamber demonstrated good matching between simulation and experimental results and proper operation of the device.

A comb shape rectangular slotted 1 X 4 microstrip patch array antenna is proposed and designed for wireless local area network applications. The functional parameters of the antenna namely, return loss, VSWR, radiation pattern are analyzed. The FR4 substrate is used to the proposed antenna. The dimension of proposed antenna is 143mm of width and 71mm of length and the patch dimension is 29.6mm of width and 38mm of length. The return loss and VSWR of 1 X 4 array antenna is -34.8815dB and 1.012, respectively. The rectangular slots are taken in equal length and width in order to enhance the performance.

Light-emitting diodes (LEDs) have increasingly replaced conventional lamps in the fields of general lighting and consumer electronics. In addition to the sharp price fall, this is also due to the significantly higher energy efficiency and the smaller, more compact design. Recently, their robustness and reliability have also reached a level of quality that surpasses the characteristics of conventional light sources such as halogen and fluorescent lamps. Characteristics, such as excellent design freedom and the possibility for functional integration, highlight the main qualities of molded interconnect devices (MIDs). The use of this technology does not only open doors to extend the application field of LEDs to new products but also presents challenges to the lighting industry. There are many studies dealing with the reliability of LEDs as well as with the usability of the MID technology in different fields. But, the lack of experience from the manufacturers regarding the behavior of this interesting configuration (LED/MID) over the entire life cycle prevents this technology from establishing and consolidating its existence. As LEDs in the automotive sector, especially within headlamps, assume increasingly powerful lighting tasks and are no longer used exclusively for signal transfer or for displays, thermal properties of the substrate materials and the thermo-mechanical behavior of the assembly are particularly relevant. In this context, this paper presents a deep and detailed reliability investigation of this system (LED/MID) and examines the influence of the MID substrate choice on the long-term performance of the LED. The impact of the forward current and of the ambient temperature on the junction temperature of the LED is a proven fact. Therefore, the MID effect was inspected under different operating conditions based on infrared thermography. After analyzing the occurred failure mechanisms, by means of X-ray analysis, thermal transient testing and microscopy, the resulting lifetime model is also presented and discussed.

Today's world, multiband antenna has immensely beneficial for fulfill the requirements of wireless communication. In this paper, Hybrid Fractal Antenna (HFA) is designed using three popular fractal curves koch, minkowski and moore. The generator curve is created by adding minkowski curve and invert of koch curve. This hybrid generator curve is then superimposed on moore curve to get proposed HFA. FR4 material is used for the design of proposed HFA. The effect of defected ground and dielectric constant of different materials on the performance of antenna is studied. Proposed antenna is fabricated and S11 in dB is measured using Vector Network Analyzer. A comparison between simulated and measured return loss is done. It is found that simulated and measured results are agreement with each other. The antenna parameters such as return loss, VSWR, radiation pattern, gain are described in this article. A gain of 20.1 dB is obtained at frequency 1.70 GHz. The maximum bandwidth of proposed HFA is 2870 MHz and VSWR range varies between 1.887MAX and 1.008MIN. The dimensions of proposed HFA is 41.5 × 37 mm2 which is small as compared to existing hybrid geometries in literature. This proposed HFA can be used for Bluetooth (2.4 GHz), Wi-Fi (IEEE 802.11b and 802.11g) Wireless LAN (5.5 GHz), Wireless computer networking (2.4 GHz and 5.5 GHz), Wi-MAX (5.20 GHz–5.8 GHz), Satellite communication uplink (5.90 GHz), Military satellite downlink (7.25–7.30 GHz) applications. [ABSTRACT FROM AUTHOR]

This paper presents a novel artificial magnetic conductor (AMC) loaded dipole above FR4 substrate. The proposed AMC consists of two metal layers that shield the wave from the lossy substrate leading to a significant increase in the dipole efficiency over a wide bandwidth. The dipole is fed through vias that are connected to a wideband balun placed on the opposite side of the ground plane. The proposed assembly is fabricated and characterized. Measurements, which are in a very good agreement with the electromagnetic simulations, show that the operating fractional bandwidth achieves the value of 16.2%, 1.927–2.267 GHz, with peak radiation efficiency of 72.5%. [ABSTRACT FROM AUTHOR]

The Planar Inverted F Antenna (PIFA) is mostly used in mobile communication. In this article, proposed two element PIFA is designed for 5G applications. The design process is illustrated in a systematic manner, initially single element square patch antenna with spiral slot is designed. For improving the performance of the antenna the Defected Ground Structure (DGS) is established. Subsequently the two elements Multiple Input Multiple Output (MIMO) antenna is designed. The square shaped ring slot introduced on the ground to improve the performance of the antenna. The single and double elements are operated at 3.3GHz and 3.2GHz. The antenna height is kept as 1.1mm. The patch dimension is 5.4mm5.4mm. The overall performance of the antenna in terms of S parameter, radiation pattern, envelope correlation coefficient (ECC) are investigated. It is so compact also, the simulated results are exhibited in proposed antenna is suitable for 5G mobile communication. [ABSTRACT FROM AUTHOR]

Abstract: The design of an FR4‐based UHF RFID portable quasi‐isotropic reader antenna with a circular polarization is reported. This low‐cost small size antenna consists of two crossed dipoles with dimensions of 50 × 80 × 1.6 mm3. A 3‐dB axial ratio bandwidth of 10 MHz can be obtained and a quasi‐isotropic radiation pattern is achieved. The designed antenna performances are investigated for 6 prototypes using the same substrate and different boards. A performances comparison and analysis between the different realizations are presented in this article. Results demonstrate that inaccuracies in FR4 characteristics have effects on the antenna performances. Therefore, the key parameters of this type of antennas are identified. [ABSTRACT FROM AUTHOR]

Reductions in printed circuit board line spacing and via diameters and the increased density of vias with higher aspect ratios (ratio between the thickness of the board and the size of the drilled hole before plating) are making electronic products increasingly more susceptible to material and manufacturing defects. One failure mechanism of particular concern is conductive anodic filament (CAF) formation, which typically occurs in two steps: degradation of the resin/glass fiber bond followed by an electrochemical reaction. Bond degradation provides a path along which electrodeposition occurs due to electrochemical reactions. The path can result from poor glass treatment, from the hydrolysis of the silane glass finish, or from mechanical stresses. Once a path is formed, an aqueous layer, which enables the electrochemical reactions to take place, can develop through the adsorption, absorption, and capillary action of moisture at the resin/fiber interface. This paper describes the concerns with CAF and the methods used for analyzing low-resistance failures. A case study is then given which highlights problems that arose on a commercial circuit board material used by a major telecommunications provider. [ABSTRACT FROM AUTHOR]

A comb shape rectangular slotted 1 × 4 microstrip patch array antenna is proposed and designed for wireless local area network applications. The functional parameters of the antenna namely, return loss, VSWR, radiation pattern are analyzed. The FR4 substrate is used to the proposed antenna. The dimension of proposed antenna is 143mm of width and 71mm of length and the patch dimension is 29.6mm of width and 38mm of length. The return loss and VSWR of 1 × 4 array antenna is -34.8815dB and 1.012, respectively. The rectangular slots are taken in equal length and width in order to enhance the performance. [ABSTRACT FROM AUTHOR]

This paper presents design of Compact Hybrid Multiband Antenna (CHMA) for various wireless applications. The projected antenna geometry is designed by integrating moore and gosper curves and their characteristics are investigated. The antenna reveals multiband behavior along with satisfactory values of all performance parameters in spite of less complexity and compact size. The small cost simulated antenna is designed on FR4 substrate, which shows gain of 16.65 dB along with return loss of −18.39 dB and VSWR of 1.27 at 2.4 GHz frequency. Simulated results exhibits six operational bands that cover various significant frequency bands like Air traffic control RADAR (0.96-1.215 GHz), GSM (1.85-1.99 GHz), Wi-Fi (2.4 GHz for 802.11b, 802.11n and 802.11g), WLAN 802.11a/b (5.15-5.35 GHz), WLAN 802.11ac (5.5 GHz) and military satellite applications (7.9-8.4 GHz). The simulation results of antenna in terms of antenna parameters like Return Loss (RL), radiation pattern, Voltage Standing Wave Ratio (VSWR) and Gain (G) are evaluated using HFSS (High Frequency Structural Simulator); v13 software. The hybrid antenna is designed with line feed having compact size of 55 mm (L) × 60 mm (W) × 1.6 mm (H) on FR4_epoxy substrate with ε 4.4. Both simulated and measured results are analyzed, compared and presented in the paper. Proposed antenna operates from 0.98 to 8.1 GHz and covers L, S, C and X band applications. [ABSTRACT FROM AUTHOR]

This article presents the long-term (1,000 h) behavior of two printed-circuit boardmaterials (Panasonic R1755V, a high-TG glass-epoxy composite and Arlon 85N, a polyimide-based laminate) stored at high temperature (190°C). Tests are performed in air and in nitrogen atmospheres. Electrical and physical measurements are performed regularly (once per week). Almost no degradation is observed for both materials when stored in nitrogen. On the contrary, the board stored in air shows the consequences of ageing. This is especially true for the glass-epoxy material, which becomes unusable after 2 w, because of large swelling. [ABSTRACT FROM AUTHOR]

A planar modified Sierpinski-Meander hybrid fractal antenna suitable for future wireless communication networks capable of exhibiting heptaband behavior has been presented in this paper. Proposed radiating structure is obtained by combining a modified Sierpinski gasket and Meander like antenna (for lower frequency) to obtain a hybrid structure exhibiting multiband behavior. Difficulty of designing a complex fractal structure has been eased by using scripting method (*.vbs) in HFSS obtained from IFS and MATLAB. Proposed antenna has partial-defected L-shaped ground structure which helps to obtain higher values of Gain. It has dimensions of 54 × 46 × 1.6 mm and resonates at 2.4, 4.437, 5.38, 7.01, 7.60, 8.41 and 9.09 GHz which covers useful applications like Bluetooth, WLAN, Wi-Fi, ISM, RFID, 4G/LTE, radiolocation and mobile/fixed satellite service. Prototype of the proposed structure is fabricated on FR4 substrate and tested. Measured results are analyzed and compared which are in good agreement with the simulated ones. [ABSTRACT FROM AUTHOR]

In this work, two previously reported low-cost design techniques for high-gain microstrip antennas are compared based on detailed parameter study. Both of these methods exploit a combination of a spacer and a layer of FR4 epoxy. The distinguishing feature of the said methods is the position of the metallization. A parameter study is performed on the thickness of the FR4 layer and its effect on the antenna gain, efficiency and pattern symmetry is reported. Capability of these methods is designing high-gain arrays is studied and specific design examples are provided. It is shown that the first method has superior performance in the sense of gain and efficiency. Especially, the first method supersedes the second one for high-gain arrays. As well, it is shown that the first method is a pure microstrip alternative to another previously reported technique wherein a CNC milled waveguide structure is exploited as the feed network. [ABSTRACT FROM AUTHOR]

In this Letter ultra‐low frequency probes for measuring time‐varying magnetic field produced in gradient coils were designed, fabricated, and tested. A 1 cm radius induction loop antenna followed by an instrumentational amplifier with a gain of 40 dB and a cutoff frequency of 30 KHz was designed to measure the magnetic field. The probe was fabricated on a single‐sided PCB, FR4 of thickness 1.57 mm and copper of thickness 35 μm was employed in a dB/dt exposure system within a saline phantom using 3D printed waterproofed cover. Simulation and measurement results of the magnetic field were in good agreements. [ABSTRACT FROM AUTHOR]

Kondisi infrastruktur dan tata letak gedung pada node pemasangan wireless LAN yang tidak sesuai dengan karakeristik antena bawaan access point yaitu omnidirectional membuat sarana hotspot menjadi kurang maksimal. Pada kasus lain ada kalanya suatu saat hotspot mengalami gangguan di beberapa titik. Dan penanganan gangguan ini biasanya memerlukan waktu beberapa hari bahkan berlarut-larut dan ini sangat menyita kebutuhan informasi yang dibutuhkan oleh pengguna dari fasilitas internet hotspot yang disediakan. Idealnya sarana backup jaringan sangat perlu diadakan, salah satu cara diantaranya dengan membuka akses titik hotspot baru di titik yang sama untuk sarana backup. Perancangan dan pembuatan antena mikrostrip akan menggunakan substrat FR4 dengan elemen peradiasi berbentuk lingkaran (circular) dengan slot yang disusun secara array dengan jumlah elemen peradiasi 4 elemen. Penyusunan secara array ini selain akan meningkatkan gain juga menghasilkan pola radiasi yang bersifat unik. Hasil pembuatan antena microstrip circullar array memiliki dimensi panjang = 123,17 mm, lebar = 103,6 mm, dan ketebalan = 1,8 mm, antena mikrostrip circular array four element yang dirancang pada frekuensi kerja 2,4 GHz dan memiliki nilai VSWR sebesar 1,29; return loss sebesar - 17.949 dB; nilai gain sebesar 6.21 dBi; nilai directivity sebesar 8.76 dB. Bentuk pola radiasi mikrostrip circular array four element adalah bidirectional dengan 90°( o HP = 90o)dan 60,5°( o HP = 60,5o) pada frekuensi 2,4 Ghz.

Sensor components may markedly differ from typical silicon chips. Consequently, versatile attachment methods are required for their interconnections. Anisotropic conductive adhesives (ACA) are interesting materials for attachments of sensors due to their versatility. In this study reliability of ACA attached humidity sensors was studied in hygrothermal conditions. The reliability of the interconnections was found to be excellent even under prolonged exposure showing that high reliability can be achieved with ACA materials in sensor applications. [ABSTRACT FROM AUTHOR]

The effects of V-shaped angle variation of CPS on the antenna characteristics have been investigated through simulation and experimental results. The dimensions of antenna are 120 mm x 62 mm x 1.6 mm using FR4 material with effective dielectric permittivity of 4.3. The proposed antennas structure is based on a dipole antenna which is configurated like V letter with some different angles. The rotations of the angles are limited from 0 to 90 degree rotation. A corresponding basic dipole antenna is represented by 90 degree. The total length of the proposed antennas is λ/2. We discovered several interesting characteristics on the HPBW and directivity compared with other results using λ as the total length of antennas. The result shows that when the angle increases, the HPBW of radiation pattern decreases and consequently the directivity also increases. [ABSTRACT FROM AUTHOR]

The mechanical properties of the glass-epoxy composite material known as “G-10,” which is primarily used for electrical insulation purposes in electromechanical systems, have long been a topic of uncertainty and controversy. In the present paper, we demonstrate the application of an experimental methodology that exploits the Direct Strain Imaging (DSI) full field method to fully assess the elastic anisotropic mechanical properties of G-10. Tension and compression experiments were conducted for three distinct inclinations of the specimen orthotropic axes relative to the loading directions, while strain and displacement were monitored at relevant locations on the specimens via digital image capturing and subsequent application of DSI. Based on these experiments, we present the stress-strain experimental data, the associated data post processing, the engineering properties, the anisotropic compliance matrix and the ultimate strength properties of the G-10 composite material. Confidence bounds on the material properties based on the results from repeated tests on identical specimens are also reported. [ABSTRACT FROM AUTHOR]

Low-cost antennas are suggested for 5.8 GHz narrow-band, low-power and dual-polarized wireless bridges based on pure microstrip flat reflectarrays. A single layer of the cheapFR4 epoxy is exploited as the substrate for both of the feed and reflector. Detailed design procedure for the feed is reported. Three different elements are used for designing the reflector including rectangular dipole, unbalanced cross and square patch. Using method of moments, performance of the designs is compared from various aspects, including reflector diameter, computational cost, gain, half-power beamwidth and polarization purity. [ABSTRACT FROM AUTHOR]

In the present study, the capabilities of different chip materials for acoustic particle manipulation have been assessed with the same microfluidic device architecture, under the same actuator and flow conditions. Silicon, glass, epoxy with fiberglass filling (FR4), polydimethylsiloxane (PDMS) and polymethyl methacrylate (PMMA) are considered as chip materials. The acoustophoretic chips in this study were manufactured with four different fabrication methods: plasma etching, chemical etching, micromachining and molding. A novel chip material, FR4, has been employed as a microfluidic chip material in acoustophoretic particle manipulation for the first time in literature, which combines the ease of manufacturing of polymer materials with improved acoustic performance. The acoustic particle manipulation performance is evaluated through acoustophoretic focusing experiments with 2 μ m and 12 μ m polystyrene microspheres and cultured breast cancer cell line (MDA-MB-231). Unlike the common approach in the literature, the piezoelectric materials were actuated with partitioned cross-polarized electrodes which allowed effective actuation of different family of chip materials. Different from previous studies, this study evaluates the performance of each acoustophoretic device through the perspective of synchronization of electrical, vibrational and acoustical resonances, considers the thermal performance of the chip materials with their effects on cell viability as well as manufacturability and scalability of their fabrication methods. We believe our study is an essential work towards the commercialization of acoustophoretic devices since it brings a critical understanding of the effect of chip material on device performance as well as the cost of achieving that performance. • Selection of chip material is critical in micro-acoustofluidics. • Manipulation performance of several different chip materials are investigated. • FR4 chip material combines the advantages of polymer acoustically hard chip materials. • For the first time in the literature, the effect of choice of chip material isF investigated through electrical, vibration, thermal and cell viability perspectives as well as ease of manufacturing and scalability. [ABSTRACT FROM AUTHOR]

A hybrid fractal multiband antenna is designed by integrating Koch curve and meander antenna. Scripting method (*.vbs) is adopted to obtain the hybrid fractal structure using IFS and MATLAB. Final structure is obtained by perturbing the reference fractal shape. Proposed antenna exhibits multiband characteristics capable of operating in four different wireless frequency bands including very popular Bluetooth (2.4 GHz), WiMAX (3.4-3.7 GHz), WLAN 802.11 a/b/g (5.3-6.1 GHz) and Aeronautical radionavigation (8.68-9.05GHz). The antenna has a planar structure, compact size of 39 mm × 32 mm × 1.58 mm and is suitable for wireless applications. Prototype of the proposed structure is developed on easily available and low cost FR4 substrate. The antenna has acceptable values of return loss, VSWR and gain. Measured characteristics are in good agreement with the simulated one. [ABSTRACT FROM AUTHOR]

Anisotropic conductive adhesive films (ACF) have been widely studied for numerous applications. However, their resistance to corrosion in highly corrosive environments has been studied only very little. This study investigated the reliability and behaviour of ACFs in corrosive salt spray environment. ACF was used to attach flip chip (FC) components on FR4, liquid crystal polymer (LCP) and polyimide (PI) substrates and the FC packages were subjected to a salt spray test lasting 3000 h. The FC packages had daisy chain structures which were measured continuously in real time during testing. After testing cross sections of the tested packages were examined using an optical microscope and a scanning electron microscope (SEM). Most components failed during the test and the results showed significant differences between the various substrate materials. The LCP substrate performed considerably better than the other substrates and the PI substrate proved to have the poorest reliability. Corrosion of the pads on the substrates as well as open joints was seen in all substrate materials. The corrosion behaviour as well as the differences between the substrates showed that the substrate structure and material are critical factors in corrosive environments and should be carefully considered. The reliability of the ACF FC package with the LCP substrate was found to be good, as the test was very severe and no failures occurred during the first 625 h of testing and only 20% failed during the first 1000 h. [ABSTRACT FROM AUTHOR]

This paper presents a compact Multiband hybrid fractal antenna designed for mobile wireless applications it has planar structure and suitable for mobile applications at low cost. The proposed antenna structure is obtained by integrating a Koch curve and Minkowski curve. It exhibits multiband behavior, acceptable values of return loss, VSWR and gain in-spite of its compact size and less complexity. The proposed antenna design has been examined up to 2nd iteration of the new fractal geometry. The simulated results exhibited seven bands of operation covering some important frequency bands like GPS (L = 1227.60 MHz), bluetooth (2.41-2.49 GHz) of ISM band, WLAN 802.11 a/b (5.15-5.35 GHz) and other bands covers applications like mobile/fixed satellite and aeronautical navigation (3.876-4.375, 6.6188-7.0045, 7.9698-8.3373 and 9.1648-9.6214 GHz). Proposed antenna is designed by using scripting method of HFSS using MATLAB. [ABSTRACT FROM AUTHOR]

We report the bidirectional electrical tuning of electromagnetic energy harvesters using two different complex load topologies: capacitive load to tune in the lower frequency range and inductive load to tune in the higher frequency range respectively. A theoretical model has been developed to address the bidirectional tuning capabilities using complex loads and the model has been successfully validated against the experimental results. Four electromagnetic harvesters with different spring configurations and thus operating at different frequencies have been developed on FR4 using laser micromachining technique and a comparison of their untuned output performances has been reported. Varying the load capacitance, the resonant frequency has been tuned up to almost 1.8 Hz for both prototype 1 and 2 and up to almost 0.16 Hz for prototype 3 and 4 in the lower frequency directions. Similarly, varying the load inductance, the resonant frequency has been tuned up to 0.6 Hz for prototype 1 and 2 and up to 0.13 Hz for prototype 3 and 4 in the higher frequency directions. This tuning comes with the reduction in the output power; however the comparative experimental study shows that the tuning range can be further widened by using devices with larger electromagnetic coupling values. [ABSTRACT FROM AUTHOR]

Readily-available and low-cost commercial polymer-based composite materials, such as standard epoxy-fibreglass printed circuit board (PCB) substrates and resin-carbon thick-film piezoresistors, were evaluated as a solution for medical force sensors, such as a wrist rehabilitation device and an implantable wireless artificial knee force sensor. We show that such materials have high sensitivity, and sufficient short-term stability – provided careful mechanical design and materials selection are made - to allow fabrication of low-cost, robust sensors, with low processing temperatures compatible with electronics integration. Example load- sensing applications are a multi-axis wrist rehabilitation device and a knee prosthesis. [ABSTRACT FROM AUTHOR]

Pulse-shaping techniques have been used for many years now in Kolsky bar testing of brittle materials. The use of pulse shapers allow the experimentalist to conduct high strain rate tests on brittle materials while ensuring that the sample will achieve a state of dynamic stress equilibrium before it fails, as well as to achieve a constant strain rate loading state for a large portion of the test. The process of choosing the appropriate pulse-shaper system has typically been one of trail-and-error, sometimes requiring many experimental trails to achieve optimal results. Advances in analytic modeling of Kolsky bar tests now make it possible, in an a priori fashion, to design a pulse-shaper system to produce a known constant strain rate experiment. This article describes the approach of coupling these analytic models to an optimization technique to quickly find a pulse-shaper system that will produce an experiment at a known constant strain rate. Experiments were conducted and the model predictions compared to resulting strain rate histories for a G10 material. Stress–strain curves for G10 are presented at three different strain rates in both the in-plane and out-of-plane loading configurations with respect to the laminate plys. The G10 material is not found to be rate sensitive in either its strength or failure properties. [ABSTRACT FROM PUBLISHER]

This paper investigates the end facet roughness of multimode polymer channel waveguides fabricated on FR4 printed circuit boards, PCBs, when cut at right angles to their optical axis by milling routers for optical butt-coupling connectors and compares it with that resulting from dicing saws and polishing and proposes a novel end facet treatment. RMS surface roughness of waveguide end facets, measured by AFMs, are compared for a range of rotation speeds and translation speeds of a milling router. It was found that one-flute routers gave significantly less rough surfaces than two or three-flute routers. The best results were achieved for a one-flute router when the milling bit was inserted from the PCB side of the board with a rotation speed of 15,000 rpm and a translation speed of 0.25 m/min which minimized the waveguide core end facet RMS roughness to 183 ± 13 nm and gave input optical coupling loss of 1.7 dB ± 0.5 B and output optical coupling loss of 2.0 dB ± 0.7 dB. The lowest RMS roughness was obtained at chip loads of 16 µm/revolution. High rotation speeds should be avoided as smearing of the end facet occurs possibly due to polymer heating and softening. For the first time to our knowledge, channel waveguide optical insertion loss is shown to be linearly proportional to the ratio of the waveguide core end facet RMS roughness to its autocorrelation length. A new fabrication technique for cut waveguide end facet treatment is proposed and demonstrated which reduces the insertion loss by 2.60 dB ± 1.3 dB which is more than that achieved by the closest available index matching fluid which gave 2.23 dB ± 1.2 dB. The new fabrication method gives a more robust end facet for use in commercial products. [ABSTRACT FROM PUBLISHER]

The current work investigates the use of liquid polydimethylsiloxane (PDMS), with a 10:1 ratio of prepolymer:curing agent =10:1 as the intermediate layer for adhesive bonding with Flame Retardant 4 (FR4). The spin coating of liquid PDMS on FR4 allows irreversible adhesive bonding with the solid PDMS. The strength of the proposed adhesive bonding technique has been investigated under different treatment temperatures: oven-heated at 60 °C, 70 °C, and 80 °C, cooled down in the room temperature of 25 °C, and exposed to direct sunlight at 35 °C. All the samples were left for 6h. Investigations were conducted to ana-lyze the effect of FR4 surface roughness on the strength and quality of the adhesive bond-ing. The standard procedure of American Standard Test Measurement (ASTM) D1002 was followed to verify the strength of PDMS-FR4 adhesive bonding. Strongest adhesive bond-ing, free from air bubbles, was obtained from a sample with smooth surface of FR4 that has undergone a cooling down treatment in the room temperature of 25 °C. FR4 was coated by solder mask to obtain smooth surface. The techniques reported in this paper are simple, straightforward, and effective to be implemented with FR4 as a base material for adhesive bonding with PDMS, thus eliminating expensive and complicated operating equipment as widely used in the oxygen plasma-assisted bonding treatment. Another benefit from this adhesive bonding technique is the fact that it avoids the use of expensive oven or hot plate. [ABSTRACT FROM AUTHOR]