Where are the rare earth elements in electronics?
The "rare earth elements" are in several places in common electronics.
Strong magnets commonly use rare earth elements.
Ceramic capacitors also use rare earth elements. Pretty much any piece of modern electronic equipment will contain ceramic capacitors.
Semiconductors (transistors, diodes, and the integrated circuits built from them) all use various amounts of rare earth elements. Pure silicon is a semiconductor by itself, but it doesn't do much of interest. It has to have specific amounts of "impurities" (properly called dopants) to get it to do the cool things it does. Those dopants are purposefully (and carefully) introduced in specific amounts in specific places to make silicon semiconductor devices work.
You'll rarely (if at all) see the rare earth elements listed in a datasheet. The datasheets tell you how a part works and how to use it, not what it is made of.
Some examples of where some less-common (not necessarily true rare-earth metals) they are used in electronics manufacturing: For ICs:
Arsenic, Boron, Antimony and phosphorus are used as dopants in silicon-based processes. Platinum and tungsten have been used for contacts, tantalum in barrier layers. Usually high-k dielectrics are used for gate dielectrics, often using something like hafnium or zirconium.
Lots of phones will use RF amplifiers and LNAs based on more exotic III-V technologies, such as GaAs (Gallium Arsenide), InP (Indium-Phosphide), etc, all of which use some less-common elements too.
On PCB-level, you have components such as tantalum capacitors which (you guessed it) contain tantalum. Ceramic capacitors might use things like barium, magnesium, and paladium. Lanthanum is sometimes used in barrier layers here. I also seem to recal strontium being used here somewhere, but I don't remember where exactly.
PCBs themselves might use paladium as barrier layer for gold plating in some applications.
A chemist friend told me once that no other industry uses so much (dangerous) chemical elements and compounds than the semiconductor industry.
(this is not an exhaustive list, but just what I could remember off the top of my head)
Googling 'rare earth elements in electronics' gave me two articles(see references) which lists the specific usage of these elements in various applications:
- Cerium - the most abundant of the rare earth elements, used in magnets, electrodes and carbon-arc lighting, as a catalyst in
catalytic converters and for precision glass polishing- Neodymium - a soft silvery metal used to create strong permanent magnets for computer disks, microphones and headphones and in the production of powerful infrared lasers
- Dysprosium - one of the most highly magnetic elements used in the manufacture of electronics, computer disks, lasers, commercial lighting and energy-efficient vehicles
- Terbium - a soft, silvery metal used as an additive in rare earth magnets, in some electronic devices and in sonar systems
- Holmium - another rare earth element with powerful magnetic properties, used in the microwave equipment and nuclear control rods
- Lanthanum - a highly reactive rare earth element used in the manufacture of telescope lenses and infrared absorbent glass
- Scandium - used in the manufacture of popular consumer products such as televisions and energy-saving lamps
- Yttrium - a silvery metal found in superconductors, lasers, and surgical supplies.
References
- https://www.jjsmanufacturing.com/blog/rare-earth-elements-electronics-manufacturing
- https://www.bbc.com/news/world-17357863