Solder Joint Life Prediction from Temperature Cycle Accumulation

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Solution Overview

Problem

Existing methods cannot predict the life of solder joints in electronic circuits, leading to functional loss due to cracks before the semiconductor elements reach the end of their life, as solder joint life is typically shorter than the power cycle lifetime of semiconductor elements.

Innovation Solution

A solder joint life predictor that includes a temperature sensor, storage for a reference acceleration factor, and a calculator to determine an actual acceleration factor based on temperature variations, integrating ratios to predict the life of solder joints by comparing an integrated value with a threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electronic circuits are operated until semiconductor elements fail, then maximum utilization is achieved, but solder joints may crack and cause functional loss before semiconductor elements reach end of life

Engineering Contradiction:
Improveutilization rateVSAvoidfunctional stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention performs preliminary prediction of solder joint life by continuously monitoring temperature and calculating the integrated acceleration factor. The system predicts the remaining life of the solder joint before actual failure occurs, allowing proactive maintenance or replacement decisions to be made, thus preventing functional loss while optimizing utilization.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention implements a feedback mechanism where the temperature sensor continuously monitors solder joint temperature, the controller calculates the acceleration factor and integrated value, and this information feeds back to predict remaining life. This closed-loop feedback system enables real-time assessment of solder joint health and allows for dynamic operational decisions.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate prediction of solder joint life, allowing for proactive prevention of functional loss by stopping the electronic circuit before a crack forms, thereby improving appliance safety and reducing repair errors.

Implementation Method 1

a temperature sensor to measure temperature of a solder joint

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a reference acceleration factor, the reference acceleration factor being an acceleration factor based on a test condition of a thermal shock test

Methodology Applied
Scientific EffectThermal shock: Thermal Shock

Data Source

PatentEP3914054B1Life prediction means for solder joint, and life prediction method for solder joint
Publication Date: 2023.01.25 MITSUBISHI ELECTRIC CORP
  • EP3914054B1 patent drawingFigure 1
  • EP3914054B1 patent drawingFigure 2~3
  • EP3914054B1 patent drawingFigure 4

AI summary

A control device (10) including a solder joint life predictor includes a temperature sensor (3) that measures temperature of a solder joint on an electronic circuit board that drives a heater (7) and a motor (9), a storage (51) that stores a reference acceleration factor that is an acceleration factor based on a test condition of a thermal shock test of an electrical appliance including the electronic circuit board and a reference condition in an environment in which the electrical appliance is used, a calculator (52) that calculates an actual acceleration factor from a temperature variation range and a maximum reached temperature of the solder joint during one cycle from start to end of driving of the heater (7) or the motor (9), and integrates acceleration factor ratios each obtained by dividing the actual acceleration factor by the reference acceleration factor for each one cycle from start to end of driving of the load to obtain an integrated value of the acceleration factor ratios, and a determiner (53) that predicts the life of the solder joint by comparing the integrated value of the acceleration factor ratios with a threshold.