Interfacial and Mechanical Property Analysis of Waste Printed Circuit Boards Subject to Thermal Shock

Abstract

Waste printed circuit boards (PCBs) are the focal points for handling electric and electronic waste. In this paper, a thermal shock method was used to pretreat waste PCBs for the improvement of crushing performance. The influence of the thermal shock process on interfacial modification and mechanical property attenuation of PCB waste was studied. The appearance and layer spacing of the basal plane began to change slightly when the temperature reached 200°C. By 250°C, apparent bulging, cracking, and delamination were observed. However, pyrolysis of PCBs occurred when the temperature reached 275°C, where PCBs were carbonized. The thermogravimetric analysis of PCB particles under vacuum showed that 270°C was the starting point of pyrolysis. The tensile and impact strength of PCBs were reduced as shock temperature rose gradually, with a reduction by 2.6 and 16.5%, respectively, at 250°C from its unheated strength. The PCBs that were heated to 250°C achieved 100% liberation, increasing linearly from 13.6% for unheated PCBs through a single-level shear-crusher (2-mm mesh) and resulting in an obvious reduction of 9.5% (dB) in dust and noise at 250°C. These parameters could be helpful for establishing the operational setup for industrialscale facilities with the aim of achieving a compact process and a highly efficient recovery for waste PCBs compared with those of the traditional combination mechanical technologies.

Study of the Transference Rules for Bromine in Waste Printed Circuit Boards during Microwave-Induced Pyrolysis

“…After the pyrolysis stage, the metals contained in WPCBs are enriched and the pyrolysis residues are more fragile 28 and less hazardous compared with WPCBs. Moreover, the metallic and nonmetallic components are different in properties such as conductivity, magnetism, and density.…”

E -Waste: Characterization and Disposal through Solid State Route

“…The major challenge faced during crushing is because of direct and continual crushing and leading to localized heating which could result in pyrolysis and easy release the toxic substances [16]. It has been reported that thermal shock may be applied as a pretreatment method to change the interfacial impact and tensile strength and it has been proven to be a potential solution to reduce crushing difficulty [17]. Pyrolysis is the process of heat treatment to a sample in the absence of oxidizing atmosphere.…”

Effect of thermal shock process on the microstructure and peel resistance of single–sided copper clad laminates used in waste printed circuit boards

“…Note that the z axis represents the thickness direction of laminate. The linear CTEs for common copper foil, epoxy resin, and E-glass fiber are 16.7, approximately 15-100, and 54 parts per million (ppm)/°C, respectively (Li et al 2010b). Additional studies have revealed that the CTE value of the glass fiber in a radial direction was approximately 5 ppm/°C, while that of unreinforced epoxy resin can range from 50 to 65 ppm/°C (Sood and Pecht 2018;Zhu, Shrotriya, and Sottos et al 2003).…”

“…(1) applying rolling devices and air bed separation to separate copper foil and nonmetallic matrix automatically, so that the copper foil can be easily recycled after being bathed to remove the discolored surface and slight adhesiveness; (2) leaching the treated laminates with organic solvent for complete separation; previous studies have shown that solvents such as dimethyl sulfoxide solvent (DMSO), dimethylformamide (DMAc), N-methyl- 2-pyrrolidone (NMP), and dimethylfomamide (DMF) were helpful for dismantling the copper from nonmetallic substrates (Verma, Singh, and Mankhand 2017a, 2017b, 2017cWath et al 2015;Zhu et al 2013aZhu et al , 2013b; as the interface was already weakened by the pre-process, leaching efficiency could be improved accordingly; (3) Li et al (2010b) found that comparing with crushing directly to liberate metallic and nonmetallic of WPCBs, the thermal pretreatment process could significantly reduce energy consumption and noise (Li et al 2010b); thus, crushing should also be a potential further processing method following thermal shock.…”

“…However, these could cause an inconvenient operation and serious dust pollution. In addition, Li et al (2010b) studied the impact of the peak temperature of thermal shock treatment on the interfacial and mechanical property of WPCBs; they found that the delaminating strength of PCBs could be reduced by 58.5% at 250°C compared with those of untreated ones, and the reduction of energy consumption and noise was 41.7% and 8.2% (dB) during crushing, respectively.…”