Life predicting method for solder joint, life predicting apparatus for solder joint and electronic device

A life predicting apparatus for a solder joint comprising:

• a first memory to store a temperature history of a measurement object having a solder joint;
• a second memory to store a response surface for obtaining a strain range from at least one physical quantity of amplitude, a cycle number, a mean temperature, and a periodic length of temperature variations;
• a third memory to store a history of a damage index;
• a fourth memory to store strain variations for obtaining a strain range increasing rate from a damage index;
• a first control unit to obtain the temperature history with reference to the first memory unit;
• a second control unit to examine at least one physical quantity selected from the group consisting of amplitude, a cycle number, a mean temperature, and a periodic length of temperature variations with a cycle count method from the history information of temperature;
• a third control unit to calculate a strain range from the physical quantity examined with a cycle count with reference to the second memory unit;
• and
• a fourth control unit to calculate the strain range increasing rate from the strain range calculated by the third control unit with reference to the third memory unit and the fourth memory unit.

An electronic device comprising:

• an electronic component;
• a mounting board;
• a first joint to mechanically connect the electronic component and the mounting board and to mediate an exchange of an electric signal between the electronic component and the mounting board;
• a second joint to mechanically connect the electronic component and the mounting board and not to mediate the exchange of the electric signal between the electronic component and the mounting board;
• and
• a third joint formed between the first joint and the second joint to mechanically connect the electronic component and the mounting board and to monitor a connection state between the electronic component and the mounting board.