ABSTRACT
Printed circuit board and component fabrication technologies require an array of materials to be assembled into mechanically robust and electrically functional final products. Electronic assemblies typically use solder alloys to both electrically and mechanically connect the components to the circuit board. Solder is applied as solder paste by screen printing, stencil printing or pressure dispensing, then a reflow oven activates the flux and melts the solder. Molten solder is also used in wave soldering of surface mount and through-hole components. Both wave soldering and solder reflow rely on molten solder wetting on metal surfaces to define shape of the solder joints and to prevent short circuit bridging across insulated spaces between
metal features. In manufacturing facilities worldwide, the traditional tin-lead solder alloys are being replaced by lead-free materials in response to the international Restriction on the use of Hazardous Substances (RoHS) legislation.
