ABSTRACT
Electronic packaging is the technology of electrically and mechanically interconnecting a multiplicity of components into an integrated system. The electronic pack-
age provides a framework for mounting of and physical support for the electronic components, provides protection of devices from the environment and enables removal of heat from devices. The primary function of the package is electrical interconnection of components (e.g., integrated circuit chips, printed wiring boards, etc.) for input, distribution and output of electrical signals and power. Interconnection within a component has traditionally been made using copper circuitry, typically circuit traces for connections within a wiring plane and plated holes for connection between planes. Interconnection among components (assembly) is commonly made using solder, most often tin-lead alloys. Low-cost tin-lead solders have been used as interconnecting materials in electronics for many decades. These alloys have good electrical and mechanical properties, reasonably low melting point and good reliability, but they are not nature-friendly. The use of lead (Pb) in electronics has been controversial. Indeed, its toxic effects are well documented. As the quantity of waste related to electronic products increases, global legislative initiatives and corporate marketing strategies are driving a reduction in the use of such toxic substances in electronics. One solution is the use of lead-free solders [1]. These solders generally possess relatively higher melting points than their tin-lead counterparts. The higher reflow temperatures required for assembly with lead-free solders can compromise the integrity of an organic substrate, thus limiting the number of suitable organic packaging substrate materials that are available.
