Electrical and electronic equipment contain various fractions of valuable materials. Most of the valuable substances are found in printed circuit boards, which occur in relevant quantities mainly in the categories Office, Information and Communication Equipment as well as Entertainment and Consumer Electronics. Besides well known precious metals such as gold, silver, platinum, and palladium also scarce materials like indium and gallium start to play an important role, due to their application in new technologies (e.g flat screens, photovoltaics).
The following table presents the composition of a desktop computer plus a CRT screen in 1996. More than 80% of the weight consists of silica (glass), plastics, iron, and aluminum. Precious and scarce materials account for only a small percentage of the total weight. Nevertheless, the concentration of such metals, e.g. gold, is higher in a desktop computer than found in naturally occurring mineral ore.
Composition of a Desktop Personal Computer Based on a typical desktop computer, weighing ~27 kg
| Material name | Content (% of total weight) | Weight of material in Computer (kg) | Use | Location |
| Plastics | 22.9907 | 6.26 | Insulation | Cable, Housing |
| Lead | 6.2988 | 1.72 | Metal joining | Funnel glass in CRTs, PWB |
| Aluminum | 14.1723 | 3.86 | Structural, Conductivity | Housing, CRT, PWB, connectors |
| Germanium | 0.0016 | < 0.1 | Semiconductor | PWBs |
| Gallium | 0.0013 | < 0.1 | Semiconductor | PWBs |
| Iron | 20.4712 | 5.58 | Structural, Magnetivity | Housing, CRTs, PWBs |
| Tin | 1.0078 | 0.27 | Metal joining | PWBs, CRTs |
| Copper | 6.9287 | 1.91 | Conductivity | CRTs, PWBs, connectors |
| Barium | 0.0315 | < 0.1 | Â | Panel glass in CRTs |
| Nickel | 0.8503 | 0.23 | Structural, Magnetivity | Housing, CRT, PWB |
| Zinc | 2.2046 | 0.6 | Battery, Phosphor emitter | PWB, CRT |
| Tantalum | 0.0157 | < 0.1 | Capacitor | Capacitors/PWB, power supply |
| Indium | 0.0016 | < 0.1 | Transistor, rectifier | PWB |
| Vanadium | 0.0002 | < 0.1 | Red Phosphor emitter | CRT |
| Terbium | 0 | 0 | Green phosphor activator, dopant | CRT, PWB |
| Beryllium | 0.0157 | < 0.1 | Thermal Conductivity | PWB, connectors |
| Gold | 0.0016 | < 0.1 | Connectivity, Conductivity | Connectivity, conductivity/PWB, connectors |
| Europium | 0.0002 | < 0.1 | Phosphor activator | PWB |
| Titanium | 0.0157 | < 0.1 | Pigment, alloying agent | Housing |
| Ruthenium | 0.0016 | < 0.1 | Resistive circuit | PWB |
| Cobalt | 0.0157 | < 0.1 | Structural, Magnetivity | Housing, CRT, PWB |
| Palladium | 0.0003 | < 0.1 | Connectivity, Conductivity | PWB, connectors |
| Manganese | 0.0315 | < 0.1 | Structural, Magnetivity | Housing, CRT, PWB |
| Silver | 0.0189 | < 0.1 | Conductivity | Conductivity/PWB, connectors |
| Antinomy | 0.0094 | < 0.1 | Diodes | Housing, PWB, CRT |
| Bismuth | 0.0063 | < 0.1 | Wetting agent in thick film | PWB |
| Chromium | 0.0063 | < 0.1 | Decorative, Hardliner | Housing |
| Cadmium | 0.0094 | < 0.1 | Battery, blue-green Phosphor emitter | Housing, PWB, CRT |
| Selenium | 0.0016 | 0.00044 | Rectifiers | rectifiers/PWB |
| Niobium | 0.0002 | < 0.1 | Welding | Housing |
| Yttrium | 0.0002 | < 0.1 | Red Phosphor emitter | CRT |
| Rhodium | 0 | Â | Thick film conductor | PWB |
| Platinum | 0 | Â | Thick film conductor | PWB |
| Mercury | 0.0022 | < 0.1 | Batteries, switches | Housing, PWB |
| Arsenic | 0.0013 | < 0.1 | Doping agent in transistors | PWB |
| Silica | 24.8803 | 6.8 | Glass, solid-state devices | CRT,PWB |
Source: Microelectronics and Computer Technology Corporation (MCC). 1996.
Electronics Industry Environmental Roadmap. Austin, TX: MCC.