FR4 or aluminium (IMS) PCB: which one do you need?
A short comparison for designers: heat conduction, layer count, plated holes, typical applications and what to specify when you order.
The short answer
Choose FR4 for general electronics — it offers 1 to 6 layers, plated through-holes and dense routing. Choose an aluminium (IMS) board when heat is the real constraint of the design: LED lighting, power supplies, motor drivers and other boards with components that must be cooled through the board.
Side by side
| Property | FR4 | IMS aluminium |
|---|---|---|
| Structure | Glass-epoxy core with copper, 1 to 6 layers | Copper circuit, thin thermal dielectric, solid aluminium base |
| Heat conduction | Roughly 0.3 W/m·K — practically an insulator | Dielectric typically about 1 to 8 W/m·K, heat flows into the aluminium |
| Copper layers | 1, 2, 4 or 6 | Usually one |
| Plated through-holes | Yes | Normally none — a plated hole would short to the aluminium base |
| Typical applications | Controllers, interfaces, sensors, consumer and industrial electronics | LED lighting, switch-mode power supplies, motor controllers, automotive power electronics |
| Board separation | Routing or V-cut | Almost always routing |
| Maximum size at PCB-ELECTRA | 390 × 520 mm (1–2 layers), 335 × 440 mm (4–6 layers) | 390 × 520 mm |
| Standard silkscreen | White | Black |
When to choose IMS aluminium
- LEDs or power components dissipate heat that has to leave the board quickly.
- The circuit can be routed on a single copper layer.
- The board will be mounted on a heatsink or metal chassis.
- You want a mechanically rigid board that does not warp under heat.
Read how an IMS board is built and which layout rules apply on the IMS aluminium PCB page.
When to stay with FR4
- The design needs more than one copper layer or plated through-holes.
- The routing is dense (microcontrollers, fine-pitch components, interfaces).
- Heat is moderate and can be handled with copper area or a heatsink on the component.
For more layers see double layer, 4-layer and 6-layer boards, or the single layer page for simple designs.
What to specify when you order
- FR4: thickness 0.51–2.4 mm, copper 18, 35, 50 or 70 µm, glass transition temperature Tg 135 °C (standard), 150 °C or 170 °C.
- IMS aluminium: base thickness and thermal conductivity of the dielectric; typical base alloys are 5052 and 6061.
- Both: solder mask and silkscreen colour, surface finish (HASL lead-free) and the outline.
All options are set in the price calculator, which gives an instant estimate in euros. If you are unsure which material fits your design, contact us — our engineers will advise before you order.
Frequently asked questions
How many copper layers does an aluminium board have?
One. If you need several copper layers, use FR4.
When is an aluminium board the better choice?
When heat has to be removed, for example with LEDs and power stages, because the metal base carries the heat away from the components.
Is an aluminium board tested electrically?
Yes. Every board goes through a 100% electrical test (short circuit and open circuit, flying probe) and AOI, and aluminium boards also get a high-voltage (hi-pot) insulation test.
Browse the questions and answers →
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