P
Piotr Wyderski
- Jan 1, 1970
- 0
Speaking of high reliability... I think that it is often
a somewhat neglected issue, so I start this thread as a
mean to collect *practical* observations for people who
care about long MTBF. In other words, "if I had to build
a device which should last 50 years, I would... what?"
Resistors (if not overloaded): immortal
Ceramic capacitors: as above
Tantalum/nobium caps: ?
Electrolytic caps: disaster area
Transistors, diodes and ICs: the silicon die should not
degrade, but how about the endurance of the resin?
At least some early Polish ICs had problems here:
the thermal coefficient of the casing was not well-matched
and power cycling finally broke the bonding wires.
There were some moisture absorbtion problems, too.
Is it still an issue?
BGA: it can be expected that thermal cycling will
eventually destroy the balls, as there are no "springs"
to absorb thermal stresses. Gull wings are much better here.
FR4: ?
Soldering: the EU has done a lot in order to make
the newer devices not very reliable as a consequence
of the RoHS directive. I see nothing wrong with the
old SnPb joints, the old boards look healthy.
Conformal coating: ?
Wires: ?
Please add your comments.
Best regards, Piotr
a somewhat neglected issue, so I start this thread as a
mean to collect *practical* observations for people who
care about long MTBF. In other words, "if I had to build
a device which should last 50 years, I would... what?"
Resistors (if not overloaded): immortal
Ceramic capacitors: as above
Tantalum/nobium caps: ?
Electrolytic caps: disaster area
Transistors, diodes and ICs: the silicon die should not
degrade, but how about the endurance of the resin?
At least some early Polish ICs had problems here:
the thermal coefficient of the casing was not well-matched
and power cycling finally broke the bonding wires.
There were some moisture absorbtion problems, too.
Is it still an issue?
BGA: it can be expected that thermal cycling will
eventually destroy the balls, as there are no "springs"
to absorb thermal stresses. Gull wings are much better here.
FR4: ?
Soldering: the EU has done a lot in order to make
the newer devices not very reliable as a consequence
of the RoHS directive. I see nothing wrong with the
old SnPb joints, the old boards look healthy.
Conformal coating: ?
Wires: ?
Please add your comments.
Best regards, Piotr