Papers by Keyword: Printed Circuit Board

Abstract: Printed circuit boards (PCBs) contain many precious and hazardous metals, and the disposal of a large number of electronic wastes (e-waste) has been a serious environmental concern. The conventional metallurgy methods used to recover metals from e-wastes require higher energy expenditure besides contributing to significant environmental pollution. This necessitated an alternative approach, such as using cyanogenic and other environmental bacteria to recover metals from e-waste. Hence, the current study is aimed to explore the feasibility of Chromobacterium sp. Dyh27s2016 strain in mobilising metals from e-waste. A two-step bioleaching process was employed with the ATCC culture Chromobacterium violecium Bergonzini (12472^TM) used as a control. The metal content in the supernatant was analysed using the inductively coupled plasma - optical emission spectrometry (ICP-OES) technique. Meanwhile, the metal concentration in PCBs was also assessed using the acid reflux method followed by the ICP-OES analysis. Besides, the Chromobacterium sp. Dyh27s2016 strain was also assessed for the beta-lactam antibiotics resistance and the gene expression for extended spectrum beta-lactamase (ESBL). It was observed that Chromobacterium sp. Dyh27s2016 strain mobilises 80, 94, 52 and 56% of Cu, Fe, Zn and Ag respectively from e-waste. However, this strain was found resistant to penicillin G sodium, ampicillin sodium and ticarcillin disodium but susceptible to cefotaxime sodium antibiotics. The molecular analysis showed that this strain possessed the ESBL genes, TEM and CTX-M. The findings from this study enable potential industrial applications for recycling electronic trash using Chromobacterium Dyh27s2016 strains in future.

Abstract: Waste printed circuit board (WPCB) from waste electrical and electronic equipment (e-waste) can be recycled a precious metal part while a non-metal part was burned or landfilled, which normally generated toxic substance of organic component to environment. The research work aimed to recycle epoxy resin by hot solvent chemical extraction. Polyethylene glycol 400 (PEG400) and ethylene glycol (EG), at 180°C, were mainly using as solvent and sodium hydroxide (NaOH) as a catalyst. Extraction method was reflux technique. The thermogravimetric analysis (TGA), Specific viscosity, and Fourier transform infrared spectroscopy (FT-IR) methods were investigated and discussed. The TGA result showed that the organic composition was 40.73%wt. The maximum of percent yield was 97.89% at non-metal WPCB/PEG, equal to 0.05 g/ml. Moreover, the extracted product presented a functional group close to virgin epoxy resin according to the peak of FT-IR data. The recycled epoxy resin could be formed well on specimen by virgin epoxy resin and hardener filled with 50% recycled extraction product.

Abstract: This work focuses on possibilities to recover tin and copper by hydrometallurgical processes from printed circuit boards (PCBs) of discarded personal computers after thermal treatment. For experimental work crushed and sorted printed circuit boards with various granularity /-8 +0 mm, -8 +3 mm, -3 +0 mm/ were used. They were exposed to thermal treatment at temperatures 300 °C, 500 °C, 700 °C and 900 °C before leaching for 15, 30 and 60 minutes. The two thermal treatments were studied: in air flow, i.e. burning, and pyrolysis (without air flow). For leaching experiments 1M solution of HCl at 80 °C was used. Under the mentioned conditions both samples, the thermally treated sample of PCB as well as the original untreated printed circuit board, were leached with the aim to compare the experimental results. Weight losses during burning accounted for 5 to 35 %, while pyrolysis caused weight losses from 10 to 30 %, depending on the thermal treatment temperature. The higher the burning temperature, the higher the extraction of copper into the solution with up to 98%.However, extraction of copper from non-burned samples does not exceeded 6 %. An opposite effect has been observed during leaching of tin, where the highest extraction was reached using thermally untreated samples, and extraction decreased with an increasing burning temperature. With increasing pyrolysis temperature a higher extraction level was observed during leaching of copper and tin into the solution. The maximal extraction was reached with the leaching of thermally untreated samples, namely 6 % for copper and about 68 % for tin whereas the extraction of copper and tin achieved with thermally treated samples was 63 % and 98 %, respectively.

Abstract: Electrochemical migration (ECM) of solder joining can result in the growth of a metal deposit with dendrite structure from cathode to anode. In electronic device, this phenomenon potentially leads to the incompetence or failure of whole devices. In this paper, the ECM behaviour of printed circuit boards (PCBs) with SAC 0307, one of the low-cost lead-free solder alloys with less silver content, has been studied. The corrosion behaviour of SAC 0307 has been investigated by using sodium chloride solution in different concentrations which is between 0.01 M to 1.0 M as a medium. A Water Drop Test (WDT) was carried out and the time-to-failure of each sample has been recorded. After WDT test, the dendrite phase was identified using Variable Pressure Scanning Electron Microscope (VPSEM) with Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) to investigate its surface morphology and corrosion products. As results, it has been found that the corrosion susceptibility of SAC 0307 is greatly influenced by the concentration of the medium solution used. The voltage drop occurred was due to the dendrite grew at the cathode electrode on the PCBs and expanded to the anode electrode, indicating a significant effect of aggressive behaviour of the medium used. The rate of the dendrite growth was affected by the concentration of the medium used. The main element found in the dendrites on the SAC 0307 on PCBs was Tin as it is more mobile than Cu.

Abstract: Printed circuit board (PCB) assembly planning problem has been given lot of attention to efficiently manage the orders of different PCB products. However, little effort has been paid to describe its comprehensive model which can demonstrate all the planning problems collectively considering in the surface mount technology (SMT) lines. A mixed integer model for PCB assembly line which includes the integration of different levels of the planning problems and considered component allocation problem (line balancing), PCB model sequencing problem (mixed model sequencing problem), feeder arrangement problem and component placement sequencing problem on different SMT machines collectively. Current research is significant to solve different planning problems of the PCB assembly line simultaneously to get the overall global solution of the problem in future.

Abstract: We present magneto conductivity measurements in natural porphyrin thin films in magnetic fields of 100 Oe at room-temperature. The films used in this experiment were isolated from natural spirulina sp by chromatography procedure with n-hexane. Each layer fabricated by spin coater methods with rotation speed of 2500 rpm for 60 second is followed post heating at temperature of 60°C for 300 second. The procedure is repeated N times. Magneto-conductance effect is presented at room temperature with induce magnetic field in plane of films. The results show that ratio magneto-conductance decreases with the increase of voltage provided. The magneto-conductance ratio increase with the increase of N repetition number. Finally, both the results indicate that magneto-conductance effect could be realized due to annihilation of carrier charge.

Abstract: In modern industry, the nondestructive testing of printed circuit board (PCB) can prevent effectively the system failure and is becoming more and more important. As a vital part of the PCB, the via connects the devices, the components and the wires and plays a very important role for the connection of the circuits. With the development of testing technology, the nondestructive testing of the via extends from two dimension to three dimension in recent years. This paper proposes a three dimensional detection algorithm using morphology method to test the via. The proposed algorithm takes full advantage of the three dimensional structure and shape information of the via. We have used the proposed method to detect via from PCB images with different size and quality, and found the detection performances to be very encouraging.

Abstract: The printed circuit board (PCB) in the electronic waste contains a variety of metals and organic materials, including bromine, heavy metals and other pollutants. Thermal treatment is an effective method for harmless disposal of waste circuit boards with resources recycle. In this study, the composition of RF4 type waste game PCB was determined by elemental analysis and proximate analysis, followed by thermogravimetric analysis of the weight lost process in CO₂、N₂ or air, at 10°C/min, 20°C/min or 30°C/min programmable heating rate, and the thermal decomposition reaction kinetics parameters were calculated with the Kissinger method. The results show that under the CO₂ atmosphere, the weight loss process of the sample consists of the 250°C～410°C and 750°C~960°C temperature intervals; under the N₂ atmosphere, the rapid weight loss stage is between 263°C and 420°C; under the air atmosphere, the weight loss process is from 178°C to 675°C, including three minor weight loss stages. The phenolic volatile components are mainly released around 260°C～360°C under three different atmospheres, while the residual carbon is further oxidized under the air atmosphere or gasified in CO₂ at temperatures above 800°C.

Abstract: The influence of Na₂CO₃ on RF4-type waste printed circuit board (PCB) thermal degradation process in air atmosphere was studied with thermogravimetric analysis, and the reaction kinetics was calculated based on the Coats – Redfern method. It is shown that the weight loss process of WPCB in air atmosphere includes three stages. Addition of Na₂CO₃ decreases the initial temperature of the first weight loss stage of WPCB, which indicates the enhancement effect on the decomposition of the flame retardant. Addition of Na₂CO₃ increases the initial temperature of the second and third weight loss stage of WPCB, which indicates the obstruction effect on oxidation reaction. From the different mechanism function, the optimal mechanism function is f (α)=2/3(1-α)[-ln (1-α) ]³ and the range of activation energy is 30~185 kJ /mol.