| abstract |
With solder paste, the active agent and the alloy in the flux react during storage and the paste changes in quality. Solder paste with an altered quality is no longer appropriate for use in printing, for example. Further, active agent unable to escape after the alloy is melted is vaporized and produces voids, or remains in the residue and lowers the electrical reliability. Hydrotalcite is contained in a flux used for solder paste. Hydrotalcite can intercalate an active agent that is anionic within its layered main chain, so that the active agent does not react with the alloy during storage of the solder paste. The solder paste thus shows excellent storability and printing stability. Through heating, the active agent is separated from the main chain and can function as an active agent. The active agent is reincorporated when the alloy hardens, making it possible to reduce the number of voids, and, even if the active agent is present in the residue, it does not adversely affect the electrical reliability. |