The Dangerously Clean Water Used To Make Your iPhone
The ordinary person thinks of reverse-osmosis as taking “everything” out of water. RO is the process you use to turn ocean water into crystalline drinking water. And in human terms, RO does take most everything out of the water.
But for semiconductors, RO water isn’t even close. Ultra-pure water requires 12 filtration steps beyond RO. (For those of a technical bent, the final filter in making UPW has pores that are 20 nanometers wide.
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Water is a good cleaner because it is a good solvent–the so-called “universal solvent,” excellent at dissolving all kinds of things. UPW is particularly “hungry,” in solvent terms, because it starts so clean. That’s why it is so valuable for washing semiconductors.
It’s also why it’s not safe to drink. A single glass of UPW wouldn’t hurt you. But even that one glass of water would instantly start leeching valuable minerals back out of your body.
UPW sytems, right down to their Kynar plumbing, suffer biofouling. It is obviously not much, but it impacts device yields unless countered. Life is tough stuff.
Re: It’s also why it’s not safe to drink. A single glass of UPW wouldn’t hurt you. But even that one glass of water would instantly start leeching valuable minerals back out of your body.
Complete and utter baloney. In terms of osmotic pressure difference vs. the fluids in the human body, there’s no appreciable difference between “regular” RO water and UPW.
Eat a sandwich with your glass of UPW and you’ll have more “valuable minerals” in your gut than if you drank mineral water without the sandwich. We stick a lot more down our gullets than water alone. It’s not like we’re a single celled organism swimming in the stuff.
LeChatelier is at work here.