A type of
integrated circuit packaging. This package is usually found in the
DIP form factor, but there are others.
Side-brazed ceramic is the "premium" of DIP IC packaging. It is composed of two or more layers of ceramic that have internal PC-board traces, used to connect the die to the outside world. The traces usually end on the sides of the package, onto which gold-plated pins are attached. The die itself is contained in a well on the top or bottom of the chip, and sealed under a gold-plated cover.
These packages are instantly recognizeable; they are generally white or brown ceramic chips with a gold cover on the top and gold pins. Side-brazed ceramic packages are not used often because they are extremely expensive; they are mostly used for first-run prototype and production chips. Part of the reason for this is lower failure rates during packaging, and also lower failure rates in the field. When die yields start going up, the cost of the package starts becoming significant and the manufacturer generally switches to ordinary ceramic or plastic packaging.
If you find a side-brazed ceramic version of a popular processor, for instance, a Motorola 68000, or of a RAM chip, like old 4116 DRAMs, you are most likely looking at a chip that is among the first of that kind produced, and were probably expensive when originally purchased.
Since DIP packaging is going the way of the dodo, we will likely see less and less of this nifty looking IC package. If you have an MC68000 or i8088 or other "famous" chip in a side-brazed package, hang onto it. It's probably a hard to find novelty.