I read one article regarding the practical shelt life for capacitor is
only 10 years. In this case can I said regardless any lab equipment,
home electronic equipment is only last for 10 years max.due to the
behaviour of the capacitor. My friend told me that it is also apply to
any unuse transistors (stock in hand ). Can any person help me to
explain ? Thanks.

Mowhoong

Many things can affect shelf live, such as storage conditions
(humidity and temperature) and time. Electrolytic capacitors are the
most affected because the need to be 'repolarized' if they have been
sitting for a long time by SLOWLY applying voltage to them in the
correct polarity, and bringing them up to the rated voltage. By doing
this reforming properly, I've had good luck with capacitors as old as 40
years. A friend who likes to restore pre W.W.II radios has had success
with reforming caps that are 75 years old.

When a manufacturer rates a part for shelf life, they usually
make the assumption that it will be installed as new with no
preparation, or restoration of the part, and that it has to meet its
reliability spec.

I've not encountered shelf life problems with most semiconductors.

Regards,
Tim Schwartz



mowhoong wrote:

I read one article regarding the practical shelt life for capacitor is
only 10 years. In this case can I said regardless any lab equipment,
home electronic equipment is only last for 10 years max.due to the
behaviour of the capacitor. My friend told me that it is also apply to
any unuse transistors (stock in hand ). Can any person help me to
explain ? Thanks.