Thermocompression bonding (TCB) is an important process in electronic packaging and is widely seen as a promising technology for miniaturized electronic devices. However, this process usually yields a lower throughput compared to more conventional mass-reflow processes, mainly because the thermal distribution uniformity across the bonding plane, as required for reliable joints, is achieved with longer bonding dwell times. Higher throughputs could be achieved by reducing the dwell time and increasing the heating rates, but this comes at the cost of higher temperature variations between the center and edges of the bonded component, leading to defects such as nonwet or bridged. Reliable temperature distribution measurements are thus needed to eliminate these joint defects. We present a novel method of temperature measurements to quantify the thermal limits of the TCB process. A microfabricated sensor with high temporal and spatial resolution was designed and fabricated for in situ temperature profile measurements up to 250 °C. This work aims to evaluate the influence of different heating rates on the temperature distribution across the chip surface, as well as on the resulting bonding quality. The bonding quality was assessed by the evaluation of bonding pull strength and interfacial defect characterization. The results demonstrate that slow heating rates (50 °C/s) lead to bridge defects and high heating rates (>80 °C/s) induce nonwetting defects in the solder joints. The solder joint defects can be related to the temperature uniformity measurements performed with the RTD sensor, thus providing a mean to more efficiently optimize the TCB heating rate in industrial processes.

中文翻译：

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原位 热压粘合过程中温度分布优化的测量方法

热压粘合（TCB）是电子包装中的重要过程，被广泛视为微型电子设备的有希望的技术。但是，与更传统的质量回流工艺相比，该工艺通常会产生较低的产量，这主要是因为可靠的接头所需的整个粘合平面的热分布均匀性是通过更长的粘合停留时间来实现的。通过减少停留时间并提高加热速率可以实现更高的生产量，但这是以被粘结组件的中心和边缘之间的温度变化较大为代价的，从而导致诸如不湿或桥接的缺陷。因此，需要可靠的温度分布测量来消除这些接头缺陷。我们提出了一种新颖的温度测量方法来量化TCB过程的热极限。设计并制造了具有高时空分辨率的微型传感器，用于原位温度曲线测量高达250°C。这项工作旨在评估不同加热速率对芯片表面温度分布以及所产生的键合质量的影响。通过评价粘结抗拉强度和界面缺陷特征来评价粘结质量。结果表明，较低的加热速率（50°C / s）会导致桥缺陷，而较高的加热速率（> 80°C / s）会导致焊点出现非润湿缺陷。焊点缺陷可能与使用RTD传感器执行的温度均匀性测量有关，因此提供了一种手段来更有效地优化工业过程中的TCB加热速率。