This paper focuses on developing a contactless jetting technique to apply a microparticle-based silver (Ag) sintering paste suitable for pressureless sintering of miniaturized optoelectronic components. Traditional soldering methods are limited by their lower thermal conductivity and the risk of remelting at elevated operating temperature (>200 °C), which can be addressed by employing advanced sintering techniques. We detail the optimization of a contactless jet dispensing process and analyze the influence of key parameters, such as cartridge pressure, needle lift, rising-time, and open-time, on the precision and reliability of material deposition. A volumetric flow model is developed as a qualitative framework to identify parameter dependencies. Through experimental validation using square-footprint LED dice, we demonstrate a linear correlation between open-time and dot volume while highlighting falling-time as a free parameter affecting dot morphology. The reliability of both the developed jetting process and the microparticle-based paste is confirmed through shear testing of LED dies on Direct Copper Bonded (DCB) substrates, achieving shear strengths exceeding 60 MPa after 1000 hours of storage at 200 °C. This methodology demonstrates the potential for the accurate and efficient application of sintering pastes in optoelectronic packaging and paves the way for future advancements in microelectronic assembly.
Stier et al. (Thu,) studied this question.