Does someone know what this is on the LCD ribbon cable?

[mr.data]

Hello everyone,
I was wondering what this small piece of metal is on the ribbon cables from laptop LCDs?

 

[g_axelsson]

It looks like a silicon die but I don't know the exact function of it. At least it's not a metal but silicon.

Göran

 

[Yggdrasil]

Maybe a stupid question Gøran.
But Silicon (Silisium) are a "semi metal" in its basic form, aren't it?
I have always thought of it as a metal.
Does that mean it won't precipitate dissolved metals, like other metal like zinc does?

 

[Dr.xyz]

It's a source driver IC, chip on film (COF).

 

[mr.data]

Thank you Dr.xyz.
According to http://global.sharp/corporate/info/rd/tj3/pdf/12.pdf it has gold bumps in them.
How would I find out if it's worth putting them aside without actually testing the amounts of gold it contains?

 

[kurtak]

Maybe a stupid question Gøran.
But Silicon (Silisium) are a "semi metal" in its basic form, aren't it?
I have always thought of it as a metal.
Does that mean it won't precipitate dissolved metals, like other metal like zinc does?

No - silicon is not a "metal" - silicon is a "pure" element (Si) but is rarely if ever found in it's pure form

here on earth - silicon (Si) is most commonly found in/as silica (silicon dioxide or SiO2) other wise known as quartz (so think glass)

So - silicon is purified silica

in 1808, Sir Humphry Davy proposed the name "silicium" for silicon, from the Latin silex, silicis for flint, and adding the "-ium" ending because he believed it to be a metal

It was not until the mid 1900(s) that they really figured out how to purify silicon (at least on large scale) which brought us into the "silicon age" & using silicon in the production of silicon semi conductors

So - basically - silicon is a VERY purified glass

Edit to add: - I should note that although silicon is not a metal - it will alloy with metals - when it is pure forum - therefore - when smelting you need to add silica &/or lime (crushed lime glass) to your flux to slag off the silicon - or the silicon will end up alloyed with your metal (gold/silver/copper) when smelting something like bonding wires from IC chips --- Edit again; - borax &/or soda ash alone (as flux) will not slag slag off the silicon

Kurt

 

[Yggdrasil]

I have to arrest you a bit there Kurt :-D

Glass is SiO₂, not pure Silicone or Silisium as we say in our part of the world.

As I told in the post to Gøran, I have been thinking of it as a metal (errounusly obviously) because of its metallic properties.
Which led to my question of how it behave in a solution with PMs.
Will it or will it not precipitate the dissolved PMs?
Will pure Silicone dissolve in our solutions at all?
Glass needs HF or similar, I know.
Just out of curiosity.

Edit for typing errors.

 

[g_axelsson]

Silicon is very nonreactive, for example when we process ceramic chip in boiling aqua regia it doesn't affect the dies inside the chips. So it doesn't cement out any gold or silver from a solution.

It does dissolve in Hf or hot NaOH if my memory serves me.

I wouldn't call it purified silica, purified silica (SiO2) is very pure silica. It's extracted from silica.

But as Kurt says it can form alloys with metals and one such alloy is the silicon gold alloy used to braze silicon dies to ceramic capsules. I suspect that the silicon in aqua regia forms silicon dioxide on the surface and that passivates the surface so it looks like it is not affected by the acid, just like aluminium in nitric acid reacts.

Göran

 

[nickvc]

Just to add a reference silicon is used in low karat gold casting alloys to help with fluidity I believe although it could also perhaps reduce oxidation of the base metals, I’m no metalagist so I could well be wrong about it’s uses.