Solder joints fail from the size of the temperature swing, not from the heat. Scale a qualification test to your field conditions and see how many cycles the joints actually survive.
Runs entirely in your browser. Nothing is uploaded, stored, or sent anywhere.
A solder joint sits between a package and a board with different coefficients of thermal expansion. Every temperature change shears it, the joint deforms plastically, and after enough cycles a crack propagates through. The damage per cycle depends overwhelmingly on how far the temperature moves, not on how hot it gets.
Nf ∝ ΔT−n — Coffin-Manson, n ≈ 2 for SAC alloysAF = (ΔTtest/ΔTfield)n ·
exp[ Ea/k · (1/Tmax,field − 1/Tmax,test) ]
— Norris-Landzberg
With n = 2, halving the temperature swing quadruples the life. That dominates everything else in the model. A design that cycles 40 K survives roughly four times as many cycles as one that swings 80 K, regardless of the absolute temperature either runs at.
The usual thermal goal is to keep the junction cool, and for silicon reliability and electrolytic capacitor life that is right — both follow Arrhenius, where absolute temperature is what matters. Solder fatigue does not. A part that runs steadily hot can outlast one that runs cool but power-cycles hard.
So the levers are different: thermal mass and heat spreading that slow and shrink the swing, avoiding aggressive power gating on large packages, and being wary of duty cycles that happen to align with the product's thermal time constant. For the Arrhenius side of the same board see the capacitor life and board FIT tools — they pull in a different direction, and a real design has to satisfy both.
The acceleration factor is what lets a 1000-cycle −40/+125 °C test say something about ten years in a cabinet. Enter what the test survived and the field conditions, and the tool scales one to the other. Norris-Landzberg adds the maximum-temperature term to plain Coffin-Manson, which matters when the test and the field differ a lot in peak temperature — and they usually do.
Each of these runs entirely in your browser. Nothing is uploaded, stored or sent anywhere, and none of them needs an email address.
See all 49 engineering tools →
We add tools here fairly often and write up the things worth writing up — a stackup that behaved oddly, a standard that turned out to be obsolete, a calculator that was quietly wrong. Join and you get told when something new lands.
One email a month at the very most, and usually less. No drip sequence, no sales cadence, no sharing your address with anyone. Unsubscribe whenever you like.