Vapour Phase Soldering System WAM 3000 Operating Instructions

Page 41.3 Description of vapour phase reflow solderingIn the vapour phase reflow soldering process, also called the condensation solderingprocess, an inert, electrically non-conductive liquid is heated to boiling temperature. Asaturated, chemically inert vapour phase forms above the liquid. The temperature of thevapour phase is identical to the boiling point of the process medium used. When anelectronic assembly is placed in the saturated vapour zone, vapour condenses on thesurface of the assembly until the surface is at the same temperature as the vapour. Thesoldering paste, which has a melting point below the temperature of the vapour, is thenalready molten.In this way it is possible for the user to obtain the best possible soldering result withoutmajor effort.The key advantages of condensation reflow soldering are:- Oxidation-free heating process in the inert vapour phase without the use of nitrogen.- Reproducible process conditions.- No overheating of the electronic assemblies- No shadowing and as a result absolutely even heating of the entire assembly.- The heating process is independent of the shape and colour of the item soldered. Thevapour produced creeps into the finest gaps. In this way even hidden components ore.g. BGAs are evenly heated in a defined manner.- Absolutely reproducible soldering profile even for different assemblies, as the heatingprocess is defined only by the physical laws relating to the vapour phase and themedium used.- No time consuming preparation of temperature profiles.- Environmentally friendly (no MAK figures)1.4 Process descriptionThe item to be soldered, once it is placed on the process zone, is brought to the reflowtemperature by homogenous and even condensation of vapour. A completely oxidationfreemelting process is achieved by heating the assembly with process vapour from thestart. The boiling temperature of the inert liquid defines the soldering temperature.Vapour production:In the soldering zone there is an inert liquid that is heated to its boiling temperature byelectrical heaters. Once the boiling point has been reached, the liquid does not becomeany hotter. All further energy added is used for the production of vapour (evaporationenthalpy). A saturated, chemically inert vapour zone forms with a temperature identical tothat of the liquid.The vapour condenses on the surface of the item to be soldered, as the temperature of theitem to be soldered is lower than the boiling temperature. The condensation process stopsas soon as the item to be soldered has reached the temperature of the vapour. Solderalloys with a melting temperature blow the temperature of the vapour are by then alreadymolten. The soldering process is complete after the cooling phase and the item soldered islifted out of the process chamber using the lift.Cooper Tools GmbHCarl-Benz-Str. 2, 74354 Besigheim, GermanyTel: 07143/580-0; Fax 07143/580-108www.cooperhandtools.com/europe