LED Aluminum Core PCB Design to Manufacturing

The efficient operation of an electrical system greatly depends onthermal management. Unfortunately, standard fiberglass boards can’twithstand the huge amount of heat produced by high-power LED arrays.

To solve this problem, modern electronics leverage LED aluminum PCBs,also known as metal core PCBs (MCPCB) or insulated metal substrates(IMS).

The most important feature of these boards is in their structure, alayout that consists of three layers: a top copper circuit layer forelectrical pathways, a highly specialized, thermally conductivedielectric layer, and a rigid aluminum base.

This intelligently arranged layout results in a low risk of heatbeing trapped in the boards. The thin dielectric layer absorbs the heatand distributes it evenly across the metal base, which later releasesthe heat outside.

This guide covers everything you need to know about the LED aluminumPCB. You’ll learn about the structure, heat dissipation properties,material selection criteria, and manufacturing processes of theseboards.

LEDAluminum PCB vs FR-4: Which One Should You Choose?

The relationship between LED aluminum PCB and high-Tg FR-4 is one ofthe most commonly misunderstood concepts among beginner designers, andit would help to set the distinctions between these two types ofboards. 

Double-sided Aluminum PCB

A laminate starts softening, warping, and delaminating at the glasstransition temperature (Tg). A high-Tg FR-4 circuit board has higherresistance to high temperatures and has dimensional stability insoldering and operation compared to standard-Tg FR-4.

However, this parameter only defines the board’s resistance to heat,not how well it can disperse heat away from the board. Tg value does notmake FR-4 thermally conductive like aluminum, and does not substitutefor the vertical heat flow that aluminum PCBs boast of.

LED aluminum PCBs are a better choice in applications involvinghigh-power LEDs, densely populated arrays, or enclosed fixtures withoutsufficient airflow. The boards are also widely used in devices intendedfor prolonged operation in a steady state since aluminum easily releasesheat from the board.

On the other hand, FR-4 may be a good choice for low-power,low-density LED operations. With the addition of thermal vias and copperpours to spread heat, the technology works well for indicator lights andsmall decorative fixtures.

Generally, FR-4 is ideal when the LEDs don’t produce much heat, withno need for a heatsink or metal enclosure for cooling.

How AluminumMCPCBs Improve LED Heat Dissipation

Heat generated inside an LED package requires an uninterrupted pathto escape the system. In a standard aluminum MCPCB assembly, heat movesfrom the LED package to the copper layer to which the LED package issoldered. The heat in the system journeys further to the dielectriclayer before reaching the aluminum base, then through a thermalinterface material (TIM), to the heatsink or metal enclosure, andfinally escapes to the outside air.

Every stage of this heat transfer process provides its own quota ofthermal resistance, and it is up to the aluminum PCB to control just theinitial stages.

A good aluminum core PCB reduces thermal resistance between the LEDpackage and the base PCB, but it cannot compensate for the insufficientsize of the heatsink, poor mechanical contact between the heatsink andthe aluminum PCB, or lack of ventilation in the enclosure.

Hence, reducing the thermal resistance of the junction to ambientimproves brightness stability, color constancy, and longevity of theLED.  However, this should not be taken separately because all elementsof this chain, including the PCB, TIM, heatsink, and enclosure, worktogether as a whole system.

Howto Select Thermal Conductivity, Dielectric Thickness, Copper Weight, andAluminum Thickness

Aluminum MCPCB datasheets are often compared with one value – thermalconductivity of the dielectric, expressed in W/m·K. A higher W/m·K valueincreases the ability of the dielectric to conduct heat, but the effectat the LED will depend on the interaction between the conductivity ofthe dielectric, the thickness of the dielectric layer, the electricalrequirements for insulation, and the power dissipation of the LED. Themounting scheme of the PCB to the heatsink/housing also plays a role inthe overall outcome.

A thin, standard dielectric layer, for example, will give betterresults on a well-designed PCB with adequate housing contacts incomparison with a thicker, higher-conductivity layer, which doesn’tmatch other characteristics of the system.

Thick aluminum is used on large and high-power PCBs to provideadditional stiffness and spreading area. Copper weight, expressed inoz/sq ft, influences the current-carrying ability of the copper layerand heat spreading ability before heat reaches the dielectric layer.Among these listed parameters, the material of the dielectric layer hasthe largest impact on the thermal resistance through the plane.

Therefore, the dielectric layer is the most important parameter inthe selection process, while aluminum thickness and copper weight playcontributory roles in the mechanical and electrical properties of theboard.

In fewer words, choose thermal conductivity, dielectric thickness,copper weight, and aluminum thickness based on LED power dissipation,board design, and mounting conditions.

Can AluminumPCBs Be Double-Sided or Multilayer?

The standard construction of an aluminum circuit board has a singlecircuit layer mounted over the dielectric and aluminum substrate,leaving the other side of the board as bare metal. It is the simplestand most cost-effective structure and can be used in most LED lightingboards, in which the aluminum side of the circuit board will be attachedto a heatsink or a housing structure. 

However, multilayer aluminum PCB boards do exist, and they areused in cases when a design requires circuits to be placed on both sidesof the board or multiple layers of interconnection between the layers ofa circuit board. Multilayer circuit boards significantly increase designcomplexity, require additional lamination processes, higher registrationand drilling tolerances, and increased cost per unit.

In the case of LED products, which include both light-emittingcircuitry with more complex driver or control electronics, it is usuallymore efficient to use two circuit boards: one aluminum board for the LEDand another FR-4 board for the controller or connector. This keeps theLED layout simple for heat management, while giving the control circuitsenough space for dense routing.

LEDAluminum PCB Design and Manufacturing Considerations

A few design elements have a large impact on thermal performance andease of manufacture of LED aluminium PCBs. These elements are:

·         LED placement and spacing determine the heat distributionacross the aluminum layer

·         The copper area that influences the current-carryingcapability and lateral heat distribution of the board

·         Current path and trace width, sized for the actual LEDdrive current

·         Board outline and mounting hole placement, which determineshow securely and flatly the board mates with its heatsink or housing

·         Dimensional tolerances that dictate the fit within thefinal fixture

On the manufacturer’s side, a number of considerations applyregarding yield, price, and assembly quality. They include:

·         Board outline and fabrication technique used (routing,punching, or V-scoring), for both panel and final outline

·         Copper thickness and its impact on etching accuracy andcurrent-carrying capability

·         Type and pattern of solder mask applied around LED pads andheatsinking areas

·         Choice of surface finishing

·         Panelization pattern for efficient assembly anddepaneling;

·         Total dimensional tolerances needed for mounting and casefitting 

What Is an LED Aluminum PCB?

An LED aluminum PCB features three layers, and each layer plays a role in achieving the overall purpose of the board. The first is the copper layer that forms the circuits, pads, and mounting area for the LED.

Under the copper layer is the second layer, a specialized dielectric layer. This layer doesn’t conduct electricity but instead dissipates heat vertically.

The last layer is the aluminum base, whose function is to provide mechanical stiffness to the circuit and dissipate heat effectively.

In some applications, the aluminum layer isn’t involved in the circuit of the LED aluminum PCB since it doesn’t have etched traces and doesn’t conduct electricity. Its only functions are thermal and mechanical dissipation of the heat and giving necessary mechanical stiffness to the PCB to mount, handle, and reflow solder the circuit.

This simple functionality differentiates the aluminum PCB technology from the conventional multilayer PCB.

LED Aluminum PCBApplications

LED aluminum PCBs are often required for efficient and reliable LEDlighting across a number of sectors. Common applications are:

General and CommercialLighting

LED aluminum PCBs are used in high-bay industrial lighting, streetlights, downlights, panel lights, and LED bulbs to prevent overheatingand dimming.

Automotive Lighting

These boards are used in manufacturing car headlights, brake lights,and dashboard indicators, an application linked due to their vibrationresistance and thermal durability.

Power Electronics

LED aluminum boards are also common in power converters, solid-staterelays, and motor drives to manage heavy electrical loads.

Medical andSpecialized Lighting

Surgical lighting, medical examination lamps, and diagnosticequipment are common applications of LED aluminum PCBs in the medicalindustry.

Display Backlighting

Display backlighting applications include large computer monitors,television backlights, and telecommunications indicator panels toprotect adjacent heat-sensitive components.

LED Aluminum PCB Price

The cost of aluminum PCBs varies significantly depending on a fewfactors, but budget between $0.50 and $3 per square inch for an averagestandard design. It is ideal to contact a manufacturer or supplier toget a precise quote for your specific project.

To determine the cost of an aluminum PCB, factor in thesevariables:

Size

In terms of size, larger PCBs are generally more expensive comparedto the smaller ones.

Thickness

Thicker PCBs tend to be costlier than thinner variations.

Quantity

If you’re ordering larger quantities, you should expect a lower costper unit than when ordering smaller quantities.

Complexity

More complex designs are generally priced higher than simplerdesigns.

Manufacturer

Many manufacturers tend to have different pricing structures, sodiscussing your needs with your manufacturer is the best way to confirmcosts.

LED Aluminum PCB Prototyping    LEARN MORE ABOUT SERVICE

Aluminum PCB prototyping tests your design before full-scaleproduction. It is essential for identifying and resolving design issuesand ensuring the final product works as intended.

The required inputs for prototyping aluminum PCBs include:

Gerber files: Digital manufacturing blueprints forboard layers

BOM (Bill of Materials): Complete list of the neededcomponents if assembly is needed

Board dimensions: Exact physical size and shape ofthe circuit board.

Aluminum thickness: The thickness of the metal baselayer, commonly 1.0mm, 1.5mm, or 2.0mm

Dielectric requirements: Specifications for thethermally conductive insulating layer between the circuit and thealuminum

Copper weight: How thick is the copper foillayer?

Surface finish: What is the metallic finish appliedto the exposed copper

Quantity: How many prototype boards aremanufactured?

Solder mask: The color and type of protectivecoating applied to the board

Test requirements: Instructions for electrical orthermal testing before shipping.

Final Words

The LED aluminum board is a great success in electronic thermalmanagement.  Their inherent features make them suitable for use in powerelectronics with special requirements and high heat generation.

With the assurance of dispersed heat, LED aluminum has gained theheart of designers and manufacturers who cherish efficiency. With theevolution of technology, these boards will gain greater importance inelectronics design and manufacturing.

However, when working with a manufacturer, it’s best to choose aprofessional who is experienced in working with LED aluminum PCBs forthe best result. This is why you want to choose Known PCB.

Contact us today.