May 4, 1964 Electronics
[Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Electronics,
published 1930 - 1988. All copyrights hereby acknowledged.
We really have it good today compared
to the early days of the semiconductor revolution. Most of the most difficult problems
were solved long ago. Point contact devices were still fairly commonplace even in
1964. Recall that the very first manufactured solid state diodes and transistors
were the point contact type that were encapsulated in glass with a space gap where
the contact was made. That left the device vulnerable to vibration and impact damage
and to contamination if the hermetic seal failed between the metal lead and the
junction(s). Unitrode claims to have been the first to eliminate that issue with
essentially a fully bonded package. Keep in mind, however, that even the early semiconductor
device packaging was no worse that the vacuum tubes that they replaced, since the
tubes also suffered from the same vulnerabilities due to their construction. In
fact, the process used with the early solid state device packaging descended directly
from vacuum tube construction.
This is what diodes looked like before Unitrodes
Remember the fragile whisker so easily burned out?
The cavity where, in time, contaminants were sure to degrade reverse characteristics
eventually? The delicate construction that was likely to fail under thermal and
mechanical stress? The limited service life even under the best of conditions?
Unitrodes have changed all that with an entirely new approach to diode design.
The silicon wafer is high-temperature bonded directly between the terminal pins,
and a hard glass sleeve is fused to all exposed silicon. Result: a void-free junction
that can't be contaminated. Broad current-carrying surfaces that can withstand 10
watt power overloads - continuously - with no after-effect.
A one-piece unit indifferent to shock. vibration, acceleration ... unperturbed
by thermal shock or cycling from -195°C to +300°C.
Naturally you'd expect performance like this to cost a bit more, and it does.
Mainly because of rigid manufacturing standards and because every Unitrode" diode
is 100% final tested. But if you're working in high reliability, you owe it to yourself
to watch your Unitrode representative's 15-minute demonstration. We'd be happy to
send him around with our entire line of diffused 3 ampere silicon diodes, fast switching
rectifiers, 3 watt zeners, high voltage stacks and bridge assemblies. We never cease
to be amazed ourselves. Write or call ... Unitrode Transistor Products, Inc., 214
Calvary Street, Waltham, Massachusetts 02154, Tel: (617) 899-8988 TWX: (617) 894-9876.
Posted May 28, 2019