MJE15028 vs MJe15030 vs MJE15032 (and MJE15029, 031 and 033)

[akis]

The above transistors have same case (TO-220), same wattage, and the same characteristics except the Vce which differs greatly - 120V, 150V and 250V.

So my question is how is the Vce determined? Is it a physical factor, ie the distance between two areas of the silicon, the greater the distance the higher the Vce? And if the physical characteristics must be different how come all the other attributes are the same?

Practically, which ones should I choose, if 120V is more than enough than what I need? Will the 120V do a better job than the 250V somehow, since I cannot detect any differences other than Vce? Or should I just use any of them interchangeably?

[SeanB]

That is a function of the manufacturing process, and during final test the devices are binned according to the tested voltage that they have a low enough leakage. A voltage is applied and the leakage current is measured. If the device say exceeds the leakage at 150V it might be fine at 120V, so is binned for there, if it is fine at 150V it will be tested again at 250v and if the leakage is still low it is a 250V part, if more then it is a 150V part.

If they run low on the bottom end and have a need for them then often the higher voltage parts will be substituted as they meet the specs, as it will meet the spec. You might find them also graded into gain groups as well.

[akis]

That would apply to other components eg the 1N400x series which in the same package goes from 50V to 400V or even 800V?