Integrated Circuits

An INTEGRATED CIRCUIT (or I.C. for short).  It is composed of many diodes and transistors, all interconnected to form an electronic circuit.  All these interconnected transistors and diodes are on a very tiny "chip" of silicon about 1/8 inch x 1/8 inch (like this r.) A tiny chip this size today can contain 50,000 (!) transistors and diodes all interconnected to form a complex circuit.

Since a tiny chip this big would be almost impossible to handle, store, identify and assemble, it is mounted into a "Package".  The package does nothing more than make it convenient to handle, mount and connect.  The three main "packages" in use today are:

1. Dual In-Line Package (called Dip)
2. Metal Can
3. Flat Pack

There have been an infinite number of new Integrated Circuits developed in the last few years.  The known leaders in the Integrated Circuit field are: Texas Instrument, Motorola, Fairchild, Mostek, National, RCA, Harris, Raytheon, Siliconix, Signetics, etc., etc.  Each has their own unique system of identification.  However, there are a few industry standards in the Dual-in-Line package (DIP).  The commercial line is offered in a plastic package, is the cheapest, and is operable at between 0° C to +70° C.  For the same circuit, most also offer the military temp range which is -50°C to +125°C and is usually made of ceramic so as to withstand the temp extremes.  Other letter designations commonly used in manufacturers part numbers are:

In order to promote increased reliability, some manufacturers also offer their military temp range device in a "burned-in” version.  Again, as in Diodes and Transistors, this burn-in is usually for 168 hours (one week) while the device is energized and while baking in an oven.  The theory here is if a device is "weak", it will probably fail during this burn-in period (called "Infant Mortality").  Those devices that successfully pass this burn-in are then identified with each manufactures special coding (Texas Instrument uses  “SNJ” The J indicates it has been "burned-in".  Fairchild uses the suffix "---QB", again indicating a burned-in device).  Any manufacturer can build, assemble and test their devices outside the continental U.S. (AKA: "off-shore").  Not so with MIL-M-38510 devices, as you will see in the following section.

LOT DATE CODE

Manufacturers of I.C.'s identify each "lot" by a simple "LOT DATE CODE" which denotes the time period of manufacture.  It consists of four digits.  The first two is the "YEAR" and the second two is the "WEEK" of that year.

"8149" would denote the 49th week of 1981.

The LOT DATE CODE is marked on all military I.C.'s along with the part number.

The U.S. Government wrote and invoked this specification and its associated QPL (Qualified Products List) in order to monitor the design, building, testing and subsequent approval-to-manufacture of all Integrated Circuits used in military contracts. The Government used the best characteristics of MIL-STD-883 (burn-in), ordered all manufacturing to be done in the U.S., and closely controlled the "Qualifying" of a manufacturer. (QPL 38510).

A manufacturer can only mark his I.C.'s "JAN" (meaning "Joint Army Navy") after extensive testing, subsequent approval by the Government, and being listed in QPL 38510.

The subsequent Governmental part number would break down-as follows:

The second letter in the part number refers to the physical package of the unit. 
(Remember? We talked about DIP, Metal Can, and Flat Packs)

The third and last letter of the part number refers to the finish (or plating) over the individual leads or pins:

A = Solder dip on the leads or pins

B = Tin plate on the leads or pins

C = Gold plate on the leads or pins

X = This designation is sometimes used (and is recognized in the industry) as
OPTIONAL. In other words, the Engineer is stating: "I'll take any available
finish.

TO INSURE FULL UNDERSTANDING 
THE COMPLETE-BREAKDOWN IS REPEATED BELOW: