中文摘要：

拆解废弃电路板（Printed circuit board,PCB）并重用高价值元器件是一种有效的回收再利用途径。在拆解过程中如果采用不合理工艺极容易导致元器件质量下降,其中塑封芯片内部界面分层是一种常见缺陷。芯片分层通常由过高温度所致,因此有必要对拆解过程电路板温度场和升温策略开展研究。根据充分熔焊和避免芯片分层这两个目标提出了峰值温度准则和升温速率准则：峰值温度准则要求在确保充分熔焊的前提下尽量降低电路板整体温度;升温速率准则要求先快速升温后缓慢升温。建立了多温区热风加热电路板的模型,并根据此模型提出基于温度场均匀性的拆解升温策略以获得符合两条升温准则的温度曲线。利用自主研制的废弃电路板拆解机进行试验验证,结果表明：利用拆解升温策略得到的先快后慢型升温的温度场均匀性明显优于斜坡型升温;用这两种温度曲线拆解电路板得到的元器件拆解率相差很小;与斜坡型升温相比,拆解升温策略使拆解过程造成的分层芯片比例降低80%。因此,基于温度场均匀性的拆解升温策略在不明显改变拆解率的前提下可有效避免拆解造成芯片分层。

英文摘要：

Disassembling end-of-life printed circuit boards （PCBs） and reusing the high-value electronic components is an effective way of recycling. During the disassembly process, the quality of components is easily to reduce if the process is inappropriate. A common defect which usually arises in the disassembly process is interfacial delamination within plastic-encapsulated integrated circuits （ICs）. The IC delamination is mainly caused by excessive high temperature. Therefore, research of the temperature field of the PCB and the heating strategy is necessary. A peak-temperature principle and a ramp-rate principle are proposed to meet the purpose of heating, i.e. melting the solder sufficiently and avoiding the IC delamination. The peak-temperature principle requires the peak temperature of the PCB should be as low as possible on the premise of melting the solder sufficiently; the ramp-rate principle requires that the ramp-up should be fast at first, and slow when the temperature is approaching the peak temperature. Then a thermal model of PCB heated in multiple temperature zones successively with hot air is built. Combined with this model, a heating strategy is proposed based on the temperature-field uniformity to achieve the temperature profile which conforms to the two heating principles. An experiment is conducted using an independently-developed disassembly machine for end-of-life PCBs to validate the heating strategy. The experimental results show： The PCB temperature field with the fast-then-slow （FTS） ramp from the heating strategy is more uniform than the temperature field with the ramp-to-spike （RTS） which is usually used in reflow process; their component disassembly rate is very close to each other; compared with the RTS ramp, the delamination fraction caused by the disassembly process is 80% lower with the FTS ramp; and thus the proposed heating strategy can effectively reduce IC delamination during the disassembly process.