This paper discusses the use of reactive multi-layers for selective assembly of ICs (Integrated Circuits) in an LTCC (Low Temperature Co-fired Ceramics) based SiP (System-in-Package). To understand the requirements for the use of self-propagating reactive multilayers in die bonding, CFD (Computational Fluid Dynamics) simulations have been carried out to simulate the die bonding process of a silicon chip onto a ceramic LTCC substrate. Reactive foils of 40 and 80 µm thicknesses and a simulated reaction propagation speed of 1 m/s were studied and used to melt a solder preform underneath a silicon chip. The results of the CFD simulations were analysed, particularly with respect to temperature and liquid fraction contours, as well as time–temperature histories obtained from temperature probes which were included in the model, such as to approximate the real behaviour of Pt-100 temperature probes, when a real bonding process is being tracked. The CFD method, in this instance realised with ANSYS Fluent software, can track the melting and solidification of the solder as well as model the influence of latent heat, which is crucial to ascertaining the true evolution of the bonding process.

本文讨论了在基于 LTCC（低温共烧陶瓷）的 SiP（系统级封装）中使用反应性多层选择性组装 IC（集成电路）。为了了解在芯片键合中使用自蔓延反应多层的要求，已经进行了 CFD（计算流体动力学）模拟，以模拟硅芯片在陶瓷 LTCC 基板上的芯片键合过程。研究了 40 和 80 µm 厚度的反应箔和 1 m/s 的模拟反应传播速度，并将其用于熔化硅芯片下方的焊料预成型件。分析了 CFD 模拟的结果，特别是关于温度和液体分数等值线，以及从模型中包含的温度探头获得的时间-温度历史，例如，在跟踪实际粘合过程时，近似 Pt-100 温度探头的实际行为。在这种情况下，使用 ANSYS Fluent 软件实现的 CFD 方法可以跟踪焊料的熔化和凝固以及模拟潜热的影响，这对于确定键合过程的真实演变至关重要。