Heat spreader,heat slug ,and heat sink?

[Alice]

What is the difference in heat spreader,heat slug ,and heat sink in a
semiconductor device? I am confused in them. I hope that someone can
tell me the difference. Thank you for your answers.

 

[Robert Redelmeier]

What is the difference in heat spreader,heat slug ,and heat
sink in a semiconductor device?

AFAIK, heat slug is just slang for heat spreader. Flat metal
a few cm square.

A heat spreader is attached by the chip mfr. It assures a
level of temperature uniformity across the die, protects the
die back, and makes attaching the heatsink easier at a slight
cost in increased die temp.

Most Intel CPUs since the original Pentium have had heat
spreaders except for some Pentium!!! chips. Most AMD Athlons
don't have heat spreaders, and the system builder attaches
the heatsink directly to the die-back.

A heatsink is a very different, separate thing. It has
extended surface fins and often a fan to remove heat from the
heatslug or die-back. Water cooled rigs have a transfer plate.

-- Robert
`

 

[Mike Ching]

AFAIK, heat slug is just slang for heat spreader. Flat metal
a few cm square.

The only use of the term heat slug that I've noticed is the heat pipe AMD
used to transfer heat from the die to the surface of the package. It became
unnecessary when Athlons were designed with the die on the surface of the
package.

 

[keith]

The only use of the term heat slug that I've noticed is the heat pipe AMD
used to transfer heat from the die to the surface of the package. It became
unnecessary when Athlons were designed with the die on the surface of the
package.

I agree with your interpretation of "slug" (a heat transfer mechanism to
the package surface), but not with "heat-pipe". A heat-pipe is widget
that transfers heat from the device via a phase-change. Typically the
surface of the chip boils a low vapor-pressure liquid and it condenses at
the heat-sink end, moving heat in the process.

 

[Alice]

AFAIK, heat slug is just slang for heat spreader. Flat metal
a few cm square.

Thank you for your answers. But I think the heat spreader is different
from the heat slug in semiconductor package. Can you tell me the
difference in detail? Thanks.

 

[George Macdonald]

What is the difference in heat spreader,heat slug ,and heat sink in a
semiconductor device? I am confused in them. I hope that someone can
tell me the difference. Thank you for your answers.

Slug and spreader have been used interchangably by some mfrs though I tend
to think of a slug as a separate piece of (often copper) metal from the
plate which contacts external cooling devices. IOW the slug is "glued" to
the CPU die and the contact plate is "glued" to the contact plate which is
often prettied up. I may be wrong but I think of a heat spreader as a
combined slug and contact plate.

In semiconductor devices in general a heatsink is generally a separate
piece of finned metal, often painted black and in small devices, like
voltage regulators and high current transistors, is often bolted to the
device package, with some heatsink paste and maybe an insulating film
(mica) in between. Of course with modern CPUs that heatsink is a big hunk
of metal, some with esoteric finning arrangements and an attached fan to
force cool it.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

[George Macdonald]

Slug and spreader have been used interchangably by some mfrs though I tend
to think of a slug as a separate piece of (often copper) metal from the
plate which contacts external cooling devices. IOW the slug is "glued" to
the CPU die and the contact plate is "glued" to the contact plate which is
often prettied up. I may be wrong but I think of a heat spreader as a
combined slug and contact plate.

<sigh>I hope you managed to interpret what I was trying to say above.
IOW the slug is glued to the CPU die and the contact plate/spreader is
glued to the *slug*.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

[Mike Ching]

I agree with your interpretation of "slug" (a heat transfer mechanism to
the package surface), but not with "heat-pipe". A heat-pipe is widget
that transfers heat from the device via a phase-change. Typically the
surface of the chip boils a low vapor-pressure liquid and it condenses at
the heat-sink end, moving heat in the process.

I guess I should be more precise if I'm going to try to talk about
terminology. I just used pipe in the sense that the transfer is mostly
contained and was thinking of the contrast with a spreader where lateral
transfer is the goal.

 

[keith]

I guess I should be more precise if I'm going to try to talk about
terminology. I just used pipe in the sense that the transfer is mostly
contained and was thinking of the contrast with a spreader where lateral
transfer is the goal.

I think you just hit it dead-on.

Slug = thermal mass used to move heat to the sink
Spreader = thermal conductor to move heat *latterally* to the sink's surface
Pipe = transfer device using phase change to remofe heat

Disagreements?

 

[Robert Redelmeier]

I think you just hit it dead-on.

Slug = thermal mass used to move heat to the sink
Spreader = thermal conductor to move heat *latterally* to the sink's surface
Pipe = transfer device using phase change to remofe heat

Disagreements?

Could be, but then I've never seen a heatslug. All have been
bigger than the underlying die, so will do some lateral transfer.

I was going to say that a heat slug might be some of those
sink-less lids that used to be put on chips (8087) for obscure
reasons (increased heat transfer, more uniform die temp?)

-- Robert