Recycling critical raw materials from waste electronic equipment

Recycling critical raw materials
from waste electronic equipment
Table 16: Quantities of precious metals in the PCBs of a notebook
Ag [mg] Au [mg] Pd [mg]
Motherboard 248 56 25
Memory cards 33 15 4
Small PCBs 22 5 2
Hard disk drive PCB 31 5 3
Printed circuit boards for optical drive 55 5 2
Display PCB 48 18 4
Total 438 104 39
Besides the PCB, the hard disk drive platters also contain a certain amount of precious
metals. These are mostly located on the surface of the storage medium. Notebooks usually
use hard disks with a 2.5 inch format. However, some newer devices are equipped with
semiconductor flash memories. These Solid State Disk (SSD) storage media are still more
expensive than hard disks and, in addition, do not yet have the same storage capacity.
However, they have the advantage of being less susceptible to physical stress (knocks,
bumps, etc.). They also run on less electricity, which has advantages especially for mobile
devices in terms of increasing battery life. With falling unit prices and higher storage
capacities it can be anticipated that notebooks will increasingly be fitted with SSDs in the
future 15 .
Hard disk drive platters can generally be divided into those based on either glass or
aluminum in terms of their substrate material. Whilst aluminum-based platters are usually
used in a 3.5 inch format, 2.5 inch hard disk drives are primarily equipped with two or three
glass-based platters 16 . A single glass-based platter of 2.5 inch format weighs around 4.8 g.
15
There is currently no reliable data on the material composition of solid state disks. However, as far as critical
raw materials are concerned, it can be assumed that these semiconductor storage devices are important in
terms of precious metals. The effect on the total quantities of precious metals in notebooks cannot be
established at present. However, as some components containing precious metals become unnecessary
(hard disk drive PCB), the simplified assumption is made that the quantity of precious metals remains
unchanged. However, there are changes in the content of rare earths, as SSD drives do not contain
permanent magnets (see Section 3.4).
16
As hard disk drives with two data platters have flatter profiles than hard disk drives with three platters, modern
slim notebooks mainly use hard disk drives with two data platters.
21