assembly, and interconnects
Updated October 2,
here to learn about hermeticity
Click here to learn about epoxy used in electronics (new for September 2012!)
This will serve as our main page
from which we will branch out and cover some packaging topics in-depth.
Our apologies in advance, we know that this material is not well
covered yet. If anyone has any comments on the definitions below,
or material to submit (especially photos), send
This topic deserves to be huge,
but without some help from engineers like you it will take some
time to construct. If you want fame and fortune, send us some material
to add, like Nameless Insider from New Jersey did!
Microwave packaging is often
broken into two broad categories: modules (often called hybrids)
and circuit card assemblies. The intent of the two approaches is
best summarized as this:
hybrid module is you want bulletproof reliability,
Use a circuit
card assembly if you want cheap.
Below are further definitions
that will show the distinctions between various categories of microwave
packaging. One of the big distinctions between various packaging
methods is whether or not hermeticity is provided; hermetic
sealing of active devices in inert atmosphere extends
reliability and is often a requirement for military systems.
Multi-chip modules: these
combine two or more chips (integrated circuits) into a more complex
circuit. Often an MCM is a non-hermetic package. And often, the
distinction between MCM and Hybrid is blurred.
modules: hybrids combine chips (discrete or monolithic),
interconnect substrates, and passives (resistors, inductors and
capacitors) into one module. Hybrid construction almost exclusively
implies that hermeticity
is provided. Fedoras
are used to get signals into/out of the housing
yet maintain hermeticity. Often, the housing
is fabricated from low-expansion
alloys. Lids are hermetically welded on with laser or seam
Microwave Integrated Circuit
(MIC): here a circuit is constructed from discrete devices (transistors)
into a larger circuit such as an amplifier. MIC refers more to a
method of construction, than a type of packaging (such as hybrid
module). The "classic" MIC circuit is a balanced amplifier
which contains two identical transistors, a pair of Lange couplers,
and suitable blocking capacitors and bias elements such as resistors
and inductors. An MIC circuit can often be replaced with an MMIC
(monolithic microwave integrated circuit). Back in the day when
MMICs were a new technology, supporters of MIC said that no matter
what, they could always wrestle better performance from a device
than a MMIC designer could. Today, MIC construction has almost been
completely replaced with MMICs, because increased functionality
is only possible though massive integration.
wire: chip and wire refers to a method of construction,
which is the basis for MIC circuits and hybrid modules alike.
circuit card assemblies:
wiring boards form the "substrate" for CCAs. Here's
a page that offers PWB hints.
ceramics come in two flavors: low temperature (LTCC)
and high temperature (HTCC).
discharge: no matter how you package electronics, ESD is
something to consider.
Relevant books for microwave
Here's a book recommendation
for the topic of packaging:
Advanced Electronic Packaging,
by Richard K. Ulrich and William D. Brown is an encyclopedia effort
with a treasure-trove of information on various material's parameters,
different interconnect schemes, design, fabrication and assembly
of hardware, not just microwave (which we consider a plus!) Look
for it soon on our book page.
If you are developing prototype
modules in a lab, chances are you will take a lot of short cuts
and not worry about half the stuff on this page. But if you intend
to design something for production, you should learn as much as
you can about production packaging processes.
A really great book on packaging
is Advanced Electronic Packaging, by Richard K. Ulrich and
William D. Brown. It is one of the best "encyclopedia"
efforts we've seen, and we've seen a lot of lame ones. Look for
it on our book page.
Some possible future topics:
Advanced interconnects such