Gas flow simulations of a fluxless Si solder bonding oven

作者：Illes Balazs^*; Kristof Gergely

来源：Microelectronic Engineering, 2011, 88(5): 760-766.

DOI：10.1016/j.mee.2010.07.037

• Si solder bonding
• Fluxless
• Forming gas
• High-temperature soldering

In this paper the technology of the "Linn" type Si fluxless solder bonding oven and gas flow simulations of the oven are discussed. This oven is used for fixing silicon chips on metal substrates with high temperature solder bonding process. The solder is applied in a foil form which is placed between the Si chip and the metal substrate. This does not contain any flux, therefore a reducing agent has to be applied to avoid the oxidation of the joints during the soldering process. In this technology the reducing agent is the Forming gas which is a mixture of 10 vol% H-2 and 90 vol% N-2. The key factors of this soldering process was studied which are the suitable temperature (350-370 degrees C for 13-15 min) and the adequate H-2 concentration (8-10 vol.%). A detailed 3D gas flow model of the Linn oven was prepared which is based on the finite volume model (FVM) method. The thermal and gas flow circumstances - used the basic and new theoretical oven settings - were compared by simulations applied the ANSYS-FLUENT system. The gas flow model was verified by the measurements of the H-2 concentration, the temperature and the pressure inside the oven. The aim was to find new oven settings in order to improve the mechanical stability and decrease the void percent of the solder joints.

• 出版日期2011-5