Solder Joint Fatigue Calculator
Work out solder joint fatigue instantly with clear inputs, formula shown and shareable results.
About Solder Joint Fatigue Calculator
Shear strain in a solder joint is CTE mismatch times temperature swing times distance from the package centre, divided by joint height. Corner joints on a large package therefore fail first, and the Engelmaier relation converts that strain into a cycle count.
Formula
Solder fatigue
shear strain = dCTE x dT x DNP / joint height; Nf from the Coffin-Manson/Engelmaier relation
Worked example
With the default values below, Solder Joint Fatigue Calculator returns Shear strain range of 4.1143%. Change any input above and every figure here is recalculated in your browser.
Inputs used
- CTE mismatch
- 12 ppm/°C
- Temperature swing
- 80 °C
- Distance to neutral point
- 15 mm
- Joint height
- 0.35 mm
Results
- Shear strain range
- 4.1143% %
- Cycles to failure
- 0 cycles
- Shear displacement
- 14.40 µm
- Assessment
- Low cycle life - consider underfill or a smaller package
Step by step
- 1Values used
- 2Solder fatigue
- 3Shear strain range= 4.1143 %
- 4Cycles to failure= 0 cycles
- 5Shear displacement= 14.40 µm
- 6Assessment= Low cycle life - consider underfill or a smaller package
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why do corner joints fail first?
Distance to the neutral point is largest there, so displacement — and therefore strain — is greatest. Corner glue or underfill directly targets this.
How does joint height help?
Strain is displacement divided by height, so a taller joint spreads the same displacement over more material. This is why column-grid arrays outlast ball arrays.
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