To provide a crack observation method for estimating a crack by observing the entire crack area.
In a method for detecting a crack formed on a solder joint part comprised by soldering jointed parts together, corrosive reagent is so contacted to the solder joint part as to enter the crack, and a facing crack surface forming the crack is etched with the corrosive reagent, for discoloring. Next, the solder joint part is so broken that the crack is extended from the opening part to the interior part of the crack, and divided into two solder joint parts provided with a discoloring crack surface which formed the crack and a broken-out surface newly generated by breaking, respectively, and the discoloring crack surface of the solder joint part is compared with the broken- out surface exhibiting the color peculiar to the solder joint part, for discriminating the extension of the crack.
MATSUMURA YOSHITOSHI
AKIMOTO HIDEKI
ODA KUNIO
