Soldering and Fusing by Condensation Heat Transfer

When saturated vapour condenses to liquid, latent heat of vapourisation is released to the item causing the condensation, this item which is itself heated. Use is made of this natural phenomenon in order to melt solder alloys melting below 216°C in a relatively new process known both as Condensation Soldering and Vapour Phase Soldering. Solder joints of the conventional type can be produced by using condensation heating to melt strategically placed preforms or solder creams and very many joints are produced simultaneously in correctly designed equipment. Plated tin‐lead coating on printed circuit boards can also be successfully fused, in some instances without application of external fluxes. Advantages over existing heating processes include geometry independent heating, oxygen‐free environment, absolute temperature control, excellent chemical compatability, absence of residues and very high heating rates. Major benefits can include operator independence, extremely low joint cost combined with excellent joining reliability both leading to greatly reduced re‐work and consequent improvement in quality and economies. There are presently about 150 facilities operating in the USA and about ten in the UK. Many tens of millions of joints are produced each year in this way with joint costs as low as 0.03 cents and reject rates less than 0.2%