Passive alignment flip chip assembly using surface tension of liquid solder and micromechanical stops

Abstract

Assembly of single mode laser diodes requires a post bond alignment accuracy of less than 1 µm. The implementation of passive alignment in optoelectronics packaging is still a challenge. A low cost approach to achieve such high precision alignment is using the flip chip self alignment mechanism in combination with micro-mechanical stops. In order to prove that this approach is feasible test vehicles were designed and fabricated. This paper presents the concept of passive alignment pursued, the experimental setup and results thereof. The design of the test vehicles is described including the bump design as well as bumping and flip chip assembly process.

Edge Couplers With Relaxed Alignment Tolerance for Pick-and-Place Hybrid Integration of III–V Lasers With SOI Waveguides

“…Some flip-chip strategies can be applied to reduce the problem of the misalignment along the z-axis, such as making use of the edge of the coupling device as a mechanical stopper during the bonding process and taking advantage of the surface tension of the liquid solder [21].…”