High quality contact plates used for sensors and switches in electronics and motor vehicles are electrolytically tin-plated to provide corrision resistance and solderability. Around a third of the plates are then finished in a reflow process, where the layer of tin is re-melted to achieve an even better bond between the tin and the plate.
The reflow process takes place at Wilms GmbH in a roll-to-roll process and is very energy-intensive. The company, which is based in Menden, builds galvanizing plants for the tinning of steel and non-ferrous sheet metal worldwide.
In the reflow plant, Wilms has been using Heraeus infrared ovens for a long time. However, the project managers at Wilms were looking to achieve energy savings and for energy-efficient alternatives. After consultation with the application specialists from Heraeus, a solution was quickly found using innovative MAX infrared ovens . These combine infrared radiation with convection and optimum reflection. In the oven interior only quartz glass materials including QRC® nanoreflectors from Heraeus are used. MAX infrared ovens are aimed at products that need to reach very high temperatures very quickly and they transfer energy to the products particularly efficiently.
At Wilms, two MAX infrared ovens have now replaced some the standard Heraeus ovens. In the new reflow line, a reflow plate runs after tinning passes through a convection oven, which dries the moisture. It then reaches the first MAX infrared oven at a temperature of about 60°C. There, the sheet is heated very rapidly to about 200°C and thereafter brought to the required target temperature of about 230°C in the infrared standard module. Jürgen Weber, head of R+D Infrared at Heraeus Noblelight: "MAX ovens are ideal for energy-efficient, very fast heating, however, the standard infrared modules offer greater controllability so that the target temperature can be precisely achieved.”