Organic solderability protector (OSP organic solderability preservatives), earlier known as heat flux (preflux). In essence, it is a linear alkyl benzene and imidazole (ABI alkyl benzimidazole) compounds with high heat resistance, its decomposition temperature of General requirements in more than 300 ℃. Therefore, it can successfully protect the freshness of the copper surface is oxidation and contamination, high temperature welding, due to the solder removed OSP reveal fresh copper surface and quickly for solid welding and solder. But it is not suitable for multiple reflow.
Organic solderability Protectant is the basic principle of linear alkyl benzene and imidazole compounds imidazole ring with copper atoms 2d10 electronic form ligand bonds to form alkyl benzene and imidazole-copper complex. Among them, even between alkyl and attract each other through Edward fan, so that fresh copper is formed on the surface of a certain thickness (generally between 0.3 ∽ 0.5 µ m) layer, coupled with the presence of benzene, so this coating has good heat resistance and high temperature. Formation of alkyl benzene and imidazole-copper complex schematic is shown in Figure 4, where are the base (n) option or a combination of the OSP as PCB will decide if I can use. Alkyl (r) choice will affect the OSP's degree of heat resistance and high and low temperature, thus, alkyl (r) OSP is the chain length and the structure of main topics in research and development, and continuous improvement of heat resistance and improved OSP decomposition temperature of main content, are the main reasons OSP suppliers confidential.