废弃印刷线路板热重分析和动力学模型

Thermogravimetric Analysis and Kinetic Models on Pyrolysis of Waste Printed Circuit Boards

利用差热热重分析仪对两种典型的废弃印刷线路板（FR4型、PTFE型）进行了热解实验研究．并利用SEM检测了热解残余物的元素组分．结果表明，PTFE型线路板的热解温度区间为500～600℃，而FR4型线路板仅为300～400℃．热解残余物中金属与玻璃纤维组分完全分离，金属与玻璃纤维保存完好于热解坩埚中．金属片主要含有铜、金、镍等组分；FR4型线路板热解残余物中的玻璃纤维片含有硅、氧、钙、碳和铝等组分，而PTFE型线路板热解后的玻璃纤维片含有硅、氧、铝、钙、钛等组分．利用Kissinger法求得两种试样的表观动力学参数，PTFE型线路板的活化能和指前因子分别为315．83U／mol和1．57×10^17min^-1，FR4型线路板的活化能和指前因子分别为103．002kJ／mol和4．127×10^8min^-1．

Two typical kinds of printed circuit boards （PCBs）, whose substrate materials are glassfibre reinforced expoxy resin （known as FR4-type PCBs） and glassfibre reinforced polytetrafluoroethylene （known as PTFE-type PCBs） , respec- tively, were chosen as experimental materials to be pyrolized with thermogravimetric apparatus. The pyrolysis residues of the PCBs were analyzed by SEM. The results indicate that the pyrolysis temperature zones of PTFE-type PCBs and FR4-type PCBs are 500-600℃ and 300-400℃, respectively. After PCBs were pyrolyzed, the metals and glassfiber of the PCBs remained inert to the pyrolysis reaction and were separated in the pyrolysis resides. The metals in pyrolysis residues of the PCBs mainly contained copper, followed by nickel and a bit gold. The glassfiber from the pyrolysis residue of both FR4-type and PCBs PTFE-type PCBs mainly consisted of silicon, oxygen, calcium, carbon and aluminium. Besides, the fiberglass from the pyrolysis residue of the latter also contained a little titanium. The activation energy and the pre-exponent of PCBs obtained with Kissinger method were 315.830 k J/mol and 1. 570 ×10^7 min-1 for PTFE-type PCB, and 103. O92 kJ/mol and 4. 127 ×10^8 min- 1 for FR4-type PCB.