Why and where copper needs to be replaced for diamond in AI chip cooling

Copper has been the backbone of thermal design for decades. If you’ve ever seen a heat sink, cold plate, or serious cooling hardware, copper is usually somewhere in the system. So why is “copper vs diamond” even a conversation? Because modern AI hardware isn’t losing to average temperature. It’s losing to hotspots.

This article breaks down why copper remains essential and why diamond is increasingly discussed as an upgrade specifically for hotspot-limited AI compute.

The real issue isn’t rack cooling. It’s heat spreading at the hotspot.

Most people imagine cooling like this: “get heat out of the box.” But AI chips fail first in a smaller place: the last few millimeters near the hotspot, where heat is generated at extremely high intensity. So you can have an excellent cold plate, high flow rate, and sophisticated coolant loop, but still see throttling because heat can’t travel fast enough through the short path between the hotspot and that cooling system.

That’s why the most important question becomes: How quickly can you spread heat away from the hotspot before it concentrates and forces throttling?

What copper does well in AI cooling stacks

Copper is great at:

• Bulk heat conduction through large components

• Heat removal when integrated into cold plates and heat sinks

• Cost-effective scaling for widespread deployment

Copper remains the workhorse material for macro-level cooling hardware.

Where copper starts to hit limits (and why diamond enters the conversation)

Copper is “good,” but hotspots are getting sharper due to rising power density and dense packaging. The limitation copper as a heat spreader is confronting is that

• hotspot heat can be too concentrated,

• and copper cannot spread it laterally fast enough close to the source.

That’s the specific gap diamond targets.

Diamond’s value shows up when used as a near-source heat spreader: it can redistribute hotspot heat quickly, lowering peak temperature before the heat ever reaches the copper heat sink or cold plate.

In plain terms and as a sequence:

• Copper can remove heat well once it’s in the cooling hardware.

• Diamond helps prevent hotspots from becoming extreme in the first place.

Diamond isn’t replacing the entire cooling stack. It’s usually positioned as an upgrade layer that makes the rest of the stack work better. A simplified “before vs after”:

Typical approach

• hotspot → heat spreader (often copper-based) → cold plate (copper) → liquid loop

With diamond

• hotspot → diamond heat spreader → cold plate (copper) → liquid loop

So the main swap is: copper heat spreading near the source becomes diamond heat spreading near the source while copper stays in the system for heat sinks and cold plates.

Copper vs diamond for AI thermal bottlenecks

Material	Best at	Where it struggles (in AI hotspot reality)
Copper	Macro-level heat removal, cold plates, heat sinks	Flattening extreme near-source hotspots as power density climbs
Diamond	Near-source heat spreading, hotspot reduction	Integration complexity, but targets the bottleneck directly with outsized returns

Hot Take

Copper is still essential in AI cooling systems. The reason diamond is increasingly discussed is that AI’s thermal limit is often set by peak hotspot temperature, not average temperature or coolant capacity.

Diamond is a near-source heat-spreading upgrade that can lower hotspot peaks, reduce throttling risk, and unlock higher sustained performance, while the rest of the cooling system (still often copper + liquid) does the bulk heat removal.