Solder Paste and Solder Joint

A solder paste in which solder alloy powder and a flux are mixed, the flux comprising:

• rosin;
• a glycol-ether-based solvent;
• an organic acid;
• a thixotropic agent;
• a halogen compound;
• and
• an imidazole compound, wherein the halogen compound is either an amine hydrohalide or an organohalogen compound or a combination of them,
• the amine hydrohalide is salt of amine compound and hydrohalic acid,
• the hydrohalic acid includes any of hydrochloric acid and hydrobromic acid,
• an addition amount of the amine hydrohalide is 0 weight % or more to 2.5 weight % and an addition amount of the organohalogen compound is 0 weight % or more to 4 weight %,
• when the addition amount of the amine hydrohalide is 0 weight % or more to less than 0.02 weight %, the addition amount of the organohalogen compound of 0 weight % or more to less than 0.1 weight % is excluded,
• when the addition amount of the organohalogen compound is 0 weight % or more to less than 0.1 weight %, the addition amount of the amine hydrohalide of 0 weight % or more to less than 0.02 weight % is excluded,
• the addition amount of the amine hydrohalide and the addition amount of the organohalogen compound stay within a range satisfying a formula (1) as follows:
• 2.5−X−0.625Y≧0 (1)
• in which the addition amount of the amine hydrohalide is indicated by X (weight %) and the addition amount of the organohalogen compound is indicated by Y (weight %),
• an addition amount of the imidazole compound is 0.1 weight % to 10 weight %, and whereby activity of the flux acts in a temperature range from 120 degrees C. to 150 degrees C. to prevent the solder paste from being peeled from a substrate.