Guangdong Key Laboratory for Advanced Metallic Materials Processing, South China University of Technology, Guangzhou, Guangdong, People's Republic of China.
Department of Electromechanical Engineering, Guangdong University of Science and Technology, Dongguan, Guangdong, People's Republic of China.
J Air Waste Manag Assoc. 2019 Dec;69(12):1490-1502. doi: 10.1080/10962247.2019.1674751. Epub 2019 Oct 28.
Efficient pre-processing is essential to the mechanical recovery of waste printed circuit boards (WPCBs). In this work, a thermal shock pretreatment was utilized to damage the interface between metals and nonmetals of single-sided copper clad laminates (SSCCLs), which are usually employed as the base material of printed circuit boards (PCBs). The effects of three thermal shock treatment parameters-i.e., peak temperature, holding time, and thermal shock cycle times-on the adhesion strength of SSCCLs were evaluated by orthogonal experiments. Microstructures and peel resistance of SSCCLs before and after thermal shock were characterized by scanning electron microscopy (SEM) and 90° peel test, respectively. Our results showed that the impact of three major factors that influence liberation efficiency was in the sequence of peak temperature > shock cycle times > holding time. Furthermore, the optimal thermal shock level could be achieved when the peak temperature was 300°C with the soaking time of 30 min and three cycle times. In the meantime, the corresponding peel strength of the SSCCLs (0.065 N/mm) was sharply decreased by 94% in comparison with those without thermal shock treatment. The manual dismantling experimental data verified the good feasibility of the optimal thermal shock process, suggesting that the copper foil could be readily dismantled from the substrate by hand after pretreatment, with a successful separation rate of 100% and a peeling efficiency of ~ 30 seconds per piece. Therefore, the optimal thermal shock process could notably improve liberation of metals and nonmetals, which would be helpful for efficient recycling of WPCBs.: The interface between copper foil and laminate dielectric in a PCB can be weakened significantly via efficient thermal shock method. Thus, a good liberation could be achieved after thermal shock. In this work, a manual peeling of copper foil from the SSCCL substrates was achieved efficiently after optimal thermal shock pretreatment, confirming the feasibility of a shorter process of metal recovery from scrap SSCCLs without pulverization. The results will be useful for the pretreatment of recovery of the WPCBs.
有效的预处理对于废旧印刷电路板 (WPCB) 的机械回收至关重要。在这项工作中，采用热冲击预处理来破坏单面覆铜板 (SSCCL) 中金属和非金属之间的界面，SSCCL 通常用作印刷电路板 (PCB) 的基底材料。通过正交实验评估了三种热冲击处理参数（峰值温度、保温时间和热冲击循环次数）对 SSCCL 粘结强度的影响。采用扫描电子显微镜 (SEM) 和 90°剥离试验分别对热冲击前后 SSCCL 的微观结构和剥离阻力进行了表征。结果表明，影响释放效率的三个主要因素的影响顺序为峰值温度>冲击循环次数>保温时间。此外，当峰值温度为 300°C，保温时间为 30 min，循环次数为 3 次时，可达到最佳热冲击水平。同时，SSCCL 的剥离强度（0.065 N/mm）急剧下降 94%，与未经热冲击处理的 SSCCL 相比。手动拆卸实验数据验证了最佳热冲击工艺的良好可行性，表明预处理后铜箔可以很容易地用手从基板上拆卸下来，成功率为 100%，剥离效率约为 30 秒/件。因此，最佳热冲击工艺可以显著提高金属和非金属的释放效率，有助于高效回收 WPCB。
在 PCB 中，铜箔和层压板介电层之间的界面可以通过有效的热冲击方法显著削弱。因此，热冲击后可以实现良好的释放。在这项工作中，经过最佳热冲击预处理后，高效地实现了从 SSCCL 基板上手动剥离铜箔，证实了在不粉碎的情况下从废 SSCCL 中回收金属的较短工艺的可行性。研究结果将有助于 WPCB 的预处理回收。
