Techniques for Soldering Surface Mounted Devices to Printed Circuit Boards

The screen printing and reflowing of solder paste is compared with wave soldering for the attachment of surface mounted devices to PCBs. Both techniques have advantages and disadvantages which are fully discussed. The method chosen for a particular application will depend upon the production facilities available, the principal package types involved in the design, and the anticipated cost. The main advantages of the screen printing process have been found to be a relatively low soldering temperature, freedom from device orientation and package design constraints, and few proximity effects, while those for the wave soldering process have been found to be compatibility with present mass soldering operations, the ability to combine both through‐hole devices and SMDs on the same board, a single soldering operation, and a solder joint volume defined by the joint design. It is concluded that in the long term screen printing and reflow is likely to become the dominant technology, but in the intermediate term wave soldering is likely to remain attractive while manufacturers move from the established through‐hole technology to the more space‐efficient surface mounted technology.