### 1.1.3 Electronic Materials and Products

| So what are "Electronic Materials"? Ask Google and you get an answer!
| Progress in Electrical Engineering was always dependent on progress in materials. For quite some time, electrical engineering meant electromechanical engineering, and electrical products were made from "trivial" materials, as seen from a modern point of view. What was needed were cables, insulators, ferromagnetic sheet metal for transformers and generators, and a lot of metal for the general mechanics. A few applications centered around some mysterious materials - out of that grew electronics and electronic materials. But even then there were key materials:
|  | Cu wires of all kinds. Not so trivial - how do you make a insulated but still flexible wire?
|  | Insulating materials - plastics didn't quite exist yet. Mica was one of the key materials - there were mines for it!
|  | Graphite and tungsten were important, whenever things got hot, like the filament in the light bulb or in a vacuum tube.
|  | The "tube of Braun" - the "Braunsche Röhre" as it was known in Europe - the first cathode ray tube (CRT) in other words - needed complicated glass work and some ZnS as electroluminescent material
|  | Strange compounds like "phosphor bronze" were developed for contacts.
|  | And Selenium (Se) was important for rectifiers, although nobody quite understood how it worked.
| The essential break through in the thirties was the vacuum tube; with it came electronics: Rectifiers, amplifiers, radio, black-and white TV, colour TV. It's not that long ago, but obviously long enough for some not to remember!
| The next break-through was called transistor; it happened in 1947. Integrated circuits followed around 1970, and since then we witness exponential growth with growth rates in the complexity of electronics (at constant prices) of up to 40% a year!
|  | A good (german) book covering this development in some detail is Hans Queissers "Kristallne Krisen".

### 1.2.2 Electronic Materials and Electronic Products
| Electronic Products
| Electronic Materials are what you find inside the components making up electronic products. They consist of some stuff that you cannot easily exchange with something else - not even in principle - without losing the function.
|  | What you can change easily for example, is the material for the box, the housing. Use Al instead of plastic or vice versa for your video recorder - it would still work, needing at most some minor adjustments.
|  | You also may change (in principle) the metal for real wires. Using Au, Ag, or Al instead of - let's say - Cu, makes little difference for the function.
|  | But exchange any material in a "chip" (i.e. in an integrated circuit) with something else (even allowing for minor adjustments) - and that definitely will be the end of your product.
| Let's look at some typical products or product groups that contain electronic materials:
|  | Electronics in general (Computer, TV, Radio, Radar, Microwave, ...).
|  | Flat panel displays (FPD).
|  | Micromechanics and Microsystems (MEMS).
|  | Solar cells.
|  | Lasers (in particular semiconductor Lasers).
|  | Batteries, Accumulators; energy storage systems in general.
|  | Sensors, in particular solid state sensors, that convert whatever they sense directly into a current or a voltage.
|  | Fuel Cells.
|  | Magnetic Memories.

| Looking at Components
| Consider, e.g., a laptop or notebook in more detail. If you take it apart, you find the "high tech" stuff:
|  | Any number of chips, i.e. integrated circuits.
|  | Some quartz oscillators.
|  | A hard disc, i.e. a magnetic memory for the bulk memory.
|  | A reading head for the hard disc that uses the "giant magnetoresistance effect"
|  | A CD ROM, i.e. an optical memory and a semiconductor Laser
|  | A flat-panel display (FPD) using "liqiud crystals", whichis pretty big as a single component, but cannot be subdivided in smaller pieces.
| But there is also "low tech" - or so it seems:
|  | Capacitors and inductors.
|  | Switches, connectors, the keyboard as a unit.
|  | Insulation.
|  | Mechanical stuff like the disk drive, but also the housing.
| Some components betray their key material in their name ("quartz" oscillator) or by common knowledge (who, besides some so-called intellectuals, does not know that the word "chip" is almost a synonym for Silicon?), but for most components we have to look deeper - we must open them up (which will almost always destroy them). What do we find?

| Electronic Materials
| Lets open up a chip. We find
|  | Packaging material - either some polymer blend or ceramics.
|  | A "chip" mostly consisting of Si, but interlaced in an intricate pattern with other materials like P, B, As, SiO2, Si3N4, MoSi2, W, TiN, Al, Cu....
|  | A lead frame - the little pins sticking out of the package - made of some metal alloys.
|  | Tiny wires connecting the leads to the chip or some pretty sophisticated stuff doing this job.
| Now open up the FPD. You will find many materials, the most suspicious beyond what we already found in chips are:
|  | Liquid crystals, some strange liquid stuff.
|  | Amorphous Si.
|  | Indium tin oxide ITO, a transparent electrode.
|  | Plastic foils acting as polarizers.
|  | A plastic (or glass) front and end plate.
| Now lets look at the Laser coming with the CD drive :
|  | You find a complex mix of GaAs, GaAlAs, some other elements, as well as wires and packaging materials.
|  | And all of this is quite different from what you find in the Si chips!
|  | Soon you would find GaN in your Laser diode - and the capacity of your CD memory will quadruple!
| We could continue this, but by now you got the idea:
Progress in Electronic and Communication Technology is driven by Progress in Material Science (and almost nothing else)

© H. Föll (Advanced Materials B, part 1 - script)