Magnetic CPU

[IIRichard]

Hello:

While playing with an old 486 CPU, I discovered that it is strongly attracted to a magnet. Anybody got an idea why a chunk of silicon would behave this way? The heat sink was removed.

 

[Rob Lister]

Hello:

While playing with an old 486 CPU, I discovered that it is strongly attracted to a magnet. Anybody got an idea why a chunk of silicon would behave this way? The heat sink was removed.

Peel back (pry off) the top and you may find a sheet of steel (for even heat transfer). This might take some doing as it is probably ceramically affixed to the base. If not, I have no idea why it would be 'strongly' attracted.

 

[IIRichard]

Re: Re: Magnetic CPU

Peel back (pry off) the top and you may find a sheet of steel (for even heat transfer). This might take some doing as it is probably ceramically affixed to the base. If not, I have no idea why it would be 'strongly' attracted.

I'm in the process of grinding it down. I'll post the result here.

Thanks for the reply.

 

[Soapy Sam]

I'm in the process of grinding it down. I'll post the result here.


... and from that day to this, children, he was never seen or heard of again!

 

[richardm]

In the interests of science, I plonked a magnet on an 8086 processor at the weekend. No attraction!

Exciting life I lead, eh?

 

[MRC_Hans]

The magnetic material is called kovar (an iron alloy). It is used as a carrier for the chip and for the pins in old-ashioned pinned IC housings. Actually the reason to use kovar is it's relatively poor heat conductive properties. This protected the chip againd overheating during wave-soldering.

I must warn you against "grinding down" integrated circuits. Now, I don't think there is any risk with your old 486, but some IC packages contain bromide, a poisonous metal . And that IS for heat conduction. So better leave them alone, and the one you did grind down, make a through job of cleaning up.

Hans

 

[MRC_Hans]

In the interests of science, I plonked a magnet on an 8086 processor at the weekend. No attraction!

Exciting life I lead, eh?

I guess all the attraction went away from the 8086 many years ago.

Hans

 

[richardm]

 

[IIRichard]

The magnetic material is called kovar (an iron alloy). It is used as a carrier for the chip and for the pins in old-ashioned pinned IC housings. Actually the reason to use kovar is it's relatively poor heat conductive properties. This protected the chip againd overheating during wave-soldering.

I must warn you against "grinding down" integrated circuits. Now, I don't think there is any risk with your old 486, but some IC packages contain bromide, a poisonous metal . And that IS for heat conduction. So better leave them alone, and the one you did grind down, make a through job of cleaning up.

Hans

Thanks for the advice Hans. I'm actually using wet or dry sandpaper with a lubricant so there isn't any dust. It is however, slow.

 

[Stitch]

--snip--
but some IC packages contain bromide, a poisonous metal . And that IS for heat conduction. So better leave them alone, and the one you did grind down, make a through job of cleaning up.

Hans

I know my chemistry is rusty, but a bromide is a compound that contains bromine, which is a rather nasty brownish coloured, non-metallic liquid that gives of some pretty nasty fumes. It's in the halogen series along with chlorine & iodine and a couple of other less familiar ones.

 

[MRC_Hans]

I know my chemistry is rusty, but a bromide is a compound that contains bromine, which is a rather nasty brownish coloured, non-metallic liquid that gives of some pretty nasty fumes. It's in the halogen series along with chlorine & iodine and a couple of other less familiar ones.

And my English chemistry terms are rusty. It contains some bromine compound.

Hans

 

[Stitch]

And my English chemistry terms are rusty. It contains some bromine compound.

Hans

It wasn't a big dig, your English is way better than any foreign language ability of mine. Bromine still isn't a metal though

 

[MRC_Hans]

Whatever. Just don't put it in your coffee. Or anywhere else.

Hans

 

[Stitch]

Whatever. Just don't put it in your coffee. Or anywhere else.

Hans

There are rumours that the British Army used to put it in tea in to reduce the sex drive.

 

[RSLancastr]

There are rumours that the British Army used to put it in tea in to reduce the sex drive.

I didn't even know that tea had a sex drive...

 

[Powa]

I didn't even know that tea had a sex drive...

And that's how we know it worked.