[PCWorks] What's a heatsink? (Was Re: Thanks to list members, and KEEP the posts coming!)
- From: "Clint Hamilton-PCWorks Admin" <PCWorks@xxxxxxxxxxxxxxxxxxxxxxxx>
- To: <pcworks@xxxxxxxxxxxxx>
- Date: Sat, 4 Apr 2009 06:59:43 -0500
(I forgot to change the subject line of Sue's post to the
appropriate topic, so I'm doing that this time).
Technically, a device, usually metal, that draws heat away from
either a heat-sensitive device and/or a device that produces
large amounts of heat, to facilitate faster more efficient
cooling of the hot device.
In this context, it's a HSF unit (heatsink & fan) which MUST go
on the motherboard's CPU (aka processor), or the CPU will melt
(or, theoretically they are supposed to shut down via thermal
protection before it melts). There are usually HS's all over a
motherboard, and video card. Some of them will have fans on
the HS if the HS is too small or if the device gets too hot for
a HS alone. Years ago, you never saw any HS's on a mobo (aka
motherboard), and the CPU only needed a HS and not even a fan.
But the faster the chips operate, the hotter they get,
therefore the need for HS's, and larger and larger ones.
It order for a HS to work properly, it's surface ideally should
be mirror-smooth, as should the surface of the HS, and tightly
and squarely attached at perfect right angles to each other.
If there are any surface imperfections, the more of them that
exists the worse the HS will perform and the hotter the device
will get. If they are smooth enough down to the atomic-level,
no TIM (thermal interface material) is needed. But since the
two surfaces can never be like that in practical use, even
after lapping, hence the requirement of good TIM. ("Lapping"
is a multi-stepped VERY fine sanding process on both CPU and HS
surfaces in efforts to achieve these perfect mirror-smooth
surfaces). Ideally, TIM fills all the surface imperfections,
creating a greater contact area for better cooling. The
greater the contact area, the better the cooling. TIM can be
silicone based (not very good), or have copper or silver
particles in it, or PCM (phase-change material), or thermal
pads. There's a huge market of TIM, dozens and dozens of
various patented formulas, with more coming out each year.
Lapping can't really be done on non-metallic chips, like
transistors, FET's (Field Effect Transistors) or IC's
(Integrated circuit chips) because they are usually silicon or
similar material (that can operate a high temps), and you can't
exactly sand those. With those that require a HS, you usually
need more TIM to cover the greater surface imperfections. To
much TIM can actually be a thermal INSULATOR, which of course
is bad. So you always want to use as little as possible.
-Clint
God Bless,
Clint Hamilton, Owner
www.OrpheusComputing.com
www.ComputersCustomBuilt.com
www.OrpheusComputing.com/PCworks-computer-help-email-list.html
----- Original Message -----
From: "Sue Cubic"
At 10:05 AM 4/3/2009 -0500, you wrote:
>There was a time when I didn't know the difference between a
>hard drive (HDD) and a floppy drive (FDD), and didn't know
>that
>a CPU needed a heatsink!
Ok, Clint. I'll bite. What's a heatsink?
Sue (computing since 1986, and never knew I needed one!)
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