Patent ID: 8321157
Filing Date: 2012-11-27
Classification: G01R

Abstract:
1. A monitoring device for an electronic device which includes a board and at least one electronic component mounted thereon, the board and the electronic component being coupled with each other through a target junction and a dummy junction at different positions, comprising: a temperature sensor configured to detect a temperature in the electronic device; a temperature information database configured to store variation history of the temperature; a sensor temperature/strain database configured to store a strain value generated in the target junction and a strain value generated in the dummy junction with respect to each of a plurality temperatures; a fatigue characteristic database configured to store a dummy damage function representing a relation among a strain amplitude representing magnitude of variation of the strain value, a cycle number of the strain amplitude and a temperature damage value of the dummy junction indicating an accumulated fatigue on the dummy junction due to temperature variation, and a target damage function representing a relation among a strain amplitude, a cycle number of the strain amplitude and a temperature damage value of the target junction indicating an accumulated fatigue on the target junction due to temperature variation; a complex load database configured to store: (a) dummy lifetime data which defines a relation between the temperature damage value of the dummy junction and a load damage value indicating an accumulated fatigue on the dummy junction due to a first load which is different from the temperature variation; (b) target lifetime data which defines a relation between the temperature damage value of the target junction and a load damage value indicating an accumulated fatigue on the target junction due to the first load; and (c) load correspondence data which defines a relation between the load damage value of the dummy junction and the load damage value of the target junction; an electrical characteristic measurer configured to measure an electrical characteristic of the dummy junction; and a lifetime computing unit configured to: (A-1) calculate the temperature damage value of the target junction by using the target damage function based on the variation history; (A-2) estimate a lifetime of the target junction based on comparison between the temperature damage value of the target junction and a first threshold value being a temperature damage value corresponding to 0 of the load damage value of the target junction in the target lifetime data; (B-1) calculate the temperature damage value of the dummy junction by using the dummy damage function based on the temperature history data when a break of the dummy junction is detected based on the electrical characteristic measured by the electrical characteristic measurer; (B-2) compare the temperature damage value of the dummy junction with a second threshold value being a temperature damage value corresponding to 0 of the load damage value of the dummy junction in the dummy lifetime data; (B-3) calculate the load damage value of the dummy junction based on the dummy lifetime data according to the temperature damage value of the dummy junction when a difference between the second threshold value and the temperature damage value of the dummy junction is equal to or greater than a predetermined value; (B-4) calculate the load damage value of the target junction based on the load damage value of the dummy junction by using the load correspondence function; and (B-5) change the first threshold value to a temperature damage value corresponding to the load damage value of the target junction in the target lifetime data.