Metal-core

Aluminum

An aluminium core under a thin dielectric pulls heat out from under the component instead of letting it accumulate in the laminate. For power LEDs and switching stages that is the difference between rated lifetime and early degradation.

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At a glance

Core material Aluminium

Core thickness 1.0 – 3.0 mm

Dielectric 75 – 150 µm

Thermal cond. 1 – 3 W/mK

Assembly single-sided

A metal-core board — often called IMS, insulated metal substrate — is a simple sandwich: an aluminium plate, a thin thermally conductive dielectric, and a copper layer on top carrying the circuit. Heat travels the short way down through the dielectric into the metal rather than the long way sideways through FR-4.

The dielectric is where the whole design is decided. It has to conduct heat and insulate electrically, and those two demands pull in opposite directions. Thinner conducts better and insulates worse; a higher-filled dielectric conducts better and is more brittle. Which compromise is right depends on the operating voltage and on how much heat the component actually produces.

What it delivers

[ Overview ]

Heat out of the component

Thermal resistance from junction to core is a fraction of what an FR-4 build achieves. For power LEDs that translates directly into luminous flux held over lifetime.

Mechanically rigid

The metal core makes the board its own heatsink and its own stiffener. In many luminaires it is also the mounting plate, which removes a part from the assembly.

Cost-effective at volume

Single-layer aluminium boards are among the cheapest constructions in the portfolio. In LED lighting this is usually the reason they are chosen, not just the thermals.

Build and options

[ Datasheet ]

Feature	Specification
Material	Aluminium core with dielectric layer; FR-4 and polyimide hybrids
Layers	1 – 4 (single-layer is standard, multilayer on request)
Final thickness	0.5 – 2.0 mm
Copper	18 – 105 µm (set by current carrying capacity)
Dielectric	75 – 150 µm, 1.0 – 3.0 W/m·K
Surface finish	ENIG, OSP, immersion silver/tin, lead-free HASL
Typical use	LED lighting, power electronics, automotive, industrial, telecoms

The usual build for this line. Anything outside it is normally still possible — ask and we will confirm.

Aluminium-core limits

[ Specification ]

The dielectric determines both thermal performance and isolation voltage. Pick it from the operating voltage first, then check the thermal budget.

Parameter	Standard	Advanced	Note
Core thickness	1.0 / 1.5 mm	2.0 – 3.0 mm	Thicker cores spread heat further sideways
Dielectric thickness	100 µm	75 µm	Thinner conducts better, isolates less
Thermal conductivity	1.0 – 2.0 W/mK	3.0 W/mK	Of the dielectric, not of the aluminium
Isolation voltage	3 kV AC	4.5 kV AC	One minute, to IPC test conditions
Copper weight	35 / 70 µm	105 – 200 µm	Heavy copper on IMS is possible
Line / gap	150 / 150 µm	100 / 100 µm	Coarser than FR-4 — the copper is thicker
Layers	1 (single)	2 – 4	Multilayer IMS costs considerably more
Isolation clearance	≥ 0.5 mm	≥ 0.3 mm	Copper to routed edge and to any hole

Guide values for pre-selection. Binding values are confirmed per project against your data.

Typical applications

[ Use cases ]

Street and industrial LED luminaires

Vehicle headlamp and rear-lamp modules

Horticultural lighting arrays

Motor drive and inverter power stages

Switch-mode power supply modules

Solid-state relays and contactor electronics

Design rules

[ Layout ]

The points below are what most often comes back as a query after data review. Settling them before layout freeze saves a loop.

Keep copper clear of the core

The aluminium is electrically conductive. Every hole and every routed edge needs at least 0.5 mm of isolation clearance, or the circuit shorts to the core.

Design for single-sided assembly

There is only one copper layer, and the core blocks any through-connection. Anything needing a second side has to become a multilayer IMS, which changes the price bracket.

Put copper under the thermal pad

The dielectric conducts heat but the copper above it spreads it. A generous copper area under the component drops junction temperature more cheaply than a better dielectric does.

Do not bend or re-work the core

Once bent, the dielectric micro-cracks and isolation voltage falls without any visible damage. If the assembly needs a bend, form the aluminium before the circuit goes on.

Frequently asked

[ FAQ ]

Aluminium or copper core?

Aluminium handles the large majority of LED and power applications and costs far less. Copper conducts roughly twice as well and is worth the 60 – 120 % surcharge only when the thermal budget genuinely will not close otherwise.

Can I have plated through-holes?

Not to the core — it is metal. Mounting holes are drilled and left unplated with a clearance ring. If you need through-connections, you need a multilayer IMS build with an insulated via structure.

What thermal conductivity do I actually need?

Most LED work closes comfortably at 1 – 2 W/mK. Going to 3 W/mK helps only when the dielectric is already the dominant term in the thermal path — often it is the copper spreading area or the heatsink interface that limits, not the dielectric.

Which surface finish?

For LEDs, a white solder mask with immersion silver or ENIG — reflectivity matters as much as solderability. HASL is common on cost-driven single-layer parts but leaves an uneven topography.

Not sure what fits?

Get your data checked

Applications in the vehicle