Measuring of Gas Flow Speed in Reflow Furnace

Abstract

Soldering in surface mount technology (SMT) is a constantly researched area in electronic production, as it affects both the quality of soldered joints and ecology. Continuous reflow furnaces with conventional hot gas heating (air or nitrogen) are most often used. One of the factors that affects the quality and reliability of soldered joints is the flow distribution in the process part of the soldering reflow furnace. This flow distribution highly depends on the design of the nozzles. The aim of this work is to achieve a reproducible measurement of hot gas flow rate under real operation conditions. This however requires measuring the temperature inside the furnace up to $300 ^{\circ}\text{C}$. Due to the European RoHS directive introducing soldering with lead-free alloys with a higher melting point, the energy intensity of the soldering process has also been increased. An integral part of this work is therefore to create the prerequisites for optimizing the gas flow in the soldering equipment and thus achieve not only a reduction in the thermal load of the product but also a reduction in the energy consumption for the entire soldering process. For this purpose, a measuring method using a new type of sensor FS7.4W is proposed, which allows measuring the temperature and flow speed in different types of furnaces and in turn to find the optimal nozzle layout.