im trying to find out heat cycles are required to break a solder joint. but at the same time i need to make sure the component that im using is suitable and can adapt to that heat. i juz want sure the solder can be cracked without affecting the component im using such as the diode and PCB. thanks for understanding
From 50 or so years of experience with various types of electronics, most broken solder joints on a PCB are caused when the component held by the solder joint is either very hot or heavy, or sometimes both.
The usual components to suffer from this problem are:
Large resistors, usually wire wound.
Power semiconductors, large diodes or transistors which are also mounted on a heatsink.
Transformers which are held on the PCB by the connecting leads.
As well as simple heating effect considerations, I think that physical expansion and contraction plays a big part in the problem.
When the component gets hot it expands, only a small amount. But if there is no flexibility in the mounting or connection leads, there will be physical stresses on the solder joints.
After several years the joint may fail.
Whenever I have come across this effect, most of the time the repair just involved sucking out the old solder and re-making the joint with new solder. The component and the PCB suffer no damage.
However...
Where the design was poor, the resistor was running VERY hot and the thermal conduction path from the component to the joint was short, leading to overheating and discolouration of the circuit board material, the circuit tracks at the solder pad on the board can lift from the board.
This should not happen in a correctly designed circuit board.
JimB