Aluminum printed circuit boards (PCBs) are metal-based, copper-clad laminates with a good heat dissipation function. Generally, a single Aluminum PCB is composed of a three-layer structure: a circuit layer (copper foil), an insulating layer, and a metal base layer. Aluminum PCBs are commonly found in light-emitting diode (LED) lighting products. There are two sides—the white side is for soldering the LED pins, and the other side is the natural color of aluminum. Generally, the thermal conductive paste will be applied to come into contact the thermal conductive part. Very few applications are multi-layer aluminum PCB boards, which can mix-press ordinary multi-layer boards like FR-4 (glass-reinforced epoxy) with insulating layers and aluminum core.
LED aluminum substrate is often referred to by the shorthand PCB, but the material is aluminum based. In the past, our general circuit board material was glass fiber (FR-4), but because the LED heats up, the circuit board used in LED lamps is generally aluminum substrate, since it has good thermal conductivity and electrical insulation properties compared to other equipment, electrical circuit boards or fiberglass boards.
Aluminum PCB working principle
The power components are mounted on the circuit layer, and the heat generated during operation is quickly transferred to the metal base layer through the insulating layer, and then the heat is transferred from the metal base layer, culminating in the heat dissipation of the components.
Compared to FR-4, the aluminum substrate minimizes thermal resistance and has excellent thermal conductivity; compared with the thick film ceramic PCB, its mechanical properties are extremely good.
In addition, using aluminum substrates has the following unique advantages:
- MeetsRestriction of Hazardous Substances (RoHS) requirements;
- More suitable for the surface-mounted technology (SMT)process;
- In terms of circuit design, thermal diffusion is extremely well treated, thereby reducing the operating temperature of the module, extending the service life, and improving the power density and reliability;
- Reducesthe assembly of heat sinks and other hardware (including thermal interface materials), reduces product volume, and reduces hardware and assembly costs; optimizes the combination of power circuits and control circuits; and
- Replacesfragile ceramic substrate PCBs to obtain better mechanical durability.
Compose of an Aluminum PCB
1. Circuit Layer
The circuit layer (usually electrolytic copper foil) is etched to form a printed circuit, which is used to realize the assembly and connection of the components. Compared to FR-4s with the same thickness and the same line width, the aluminum substrate can carry higher current.
2. Insulation Layer
The insulating layer is the core technology of the aluminum substrate, which plays the primary role of bonding, insulation, and heat conduction. The insulating layer of the aluminum substrate is the largest thermal barrier in the power module structure. The better the thermal conductivity of the insulating layer, the more conducive to the diffusion of heat generated during the operation of the device—and the more conducive to reducing the operating temperature of the device, so as to increase the power load of the module, reduce the volume, extend the life, and increase the power output.
3. Metal Base Layer
What kind of metal is used for the insulated metal substrate depends on a comprehensive consideration of the thermal expansion coefficient, thermal conductivity, strength, hardness, weight, surface condition, and cost of the metal substrate.
Under normal circumstances, considering the cost and technical performance, aluminum plating is an ideal choice. Available aluminum plates are 6061, 5052, 1060, etc. If there are requirements for higher thermal conductivity, mechanical properties, electrical properties, or other special properties, then copper plates, stainless steel plates, iron plates and silicon steel plates can also be used.
Aluminum PCB Advantages and Performance Characteristics
Aluminum pcb Vs Fr4 PCB
Aluminum base plating (metal base heat sink [including the aluminum base plate, copper base plate, iron base plate]) is a low-alloyed Al-Mg-Si series high-plasticity alloy plate (see the figure below for the structure). This has good thermal conductivity and electrical insulation performance as well as mechanical processing performance. Compared to the traditional FR-4, the aluminum substrate adopts the same thickness and the same line width, can carry higher current, can withstand voltage up to 4500V, and the thermal conductivity is greater than 2.0. The industry is dominated by aluminum substrates.
Some other advantages include:
- Usessurface mount technology (SMT);
Street lamp aluminum substrate
- Extremely effective treatment of thermal diffusion in the circuit design scheme;
- Reducesproduct operating temperature, improves product power density and reliability, extends product service life;
- Reducesproduct volume and reduces hardware and assembly costs; and
- Replaces fragile ceramic substrates to obtain better mechanical durability.
3. Aluminum layer characteristics
- Circuit layer: copper clad laminate equivalent to ordinary PCB; the thickness of the circuit copper foil is 1ozto 10oz
- Insulation layer: The insulation layer is a layer of low thermal resistance,thermally conductive insulating material. Thickness: 0.003" to 0.006" is the core technology of aluminum-based copper clad laminates, which has obtained Underwriters Laboratories Inc. (UL)
- Aluminum Base layer: This is a metal substrate, generally aluminum or optionally This can be aluminum-based,copper-clad laminate and traditional epoxy glass cloth laminate, etc.
Compared to other materials, Aluminum PCBs use materials with incomparable advantages. Suitable for surface-mount technology (SMT) public art of power components. No radiator is needed, the volume is greatly reduced, the heat dissipation effect is excellent, and the insulation performance and mechanical performance are good.
The LED die (or semiconductor device) substrate is mainly used as a medium for heat dissipation between the LED die and the system circuit board. This substrate is combined with the LED die through the process of wire bonding, a eutectic system or flip chip. Based on heat dissipation considerations, the LED die substrates on the market are mainly ceramic substrates, which can be roughly divided into three types: thick film ceramic substrates, low temperature co-fired multilayer ceramics, and thin film ceramic substrates. For high-power LED components, thick-film or low-temperature co-fired ceramic substrates are mostly used as die heat dissipation substrates, and then the LED die and the ceramic substrate are combined with gold wires.
1200mm long led PCB
As mentioned in the introduction, this gold wire connection limits the effectiveness of heat dissipation along the electrode contacts. Therefore, major domestic and foreign manufacturers are all working hard to solve this problem. There are two solutions. One is to find a substrate material with a high heat dissipation coefficient to replace alumina—including silicon substrate, silicon carbide substrate, anodized aluminum substrate, or aluminum nitride substrate. Among them, silicon and silicon carbide substrate are semiconductor materials. Due to its characteristics, it has encountered more severe tests at this stage, and the anodized aluminum substrate is easy to conduct due to cracking resultant from the insufficient strength of the anodized oxide layer, which limits its practical application. Therefore, at this stage, the more mature and generally accepted solution is to use aluminum nitride as the heat dissipation substrate; however, the aluminum nitride substrate is not suitable for the traditional thick film process (the material must be heat-treated at 850°C in the atmosphere after the silver paste is printed; there is thus a material reliability problem), therefore, the aluminum nitride substrate circuit needs to be prepared by a thin film process. This thin film process greatly accelerates the efficiency of heat from the LED die through the substrate material to the system circuit board, thus greatly reducing the burden of heat from the LED die to the system circuit board through the metal wire, thereby achieving a high heat dissipation effect.
Aluminum PCB Application (Power Hybrid IC [HIC])
Some common applications are:
- Audio equipment: Input and output amplifiers, balanced amplifiers, audio amplifiers, preamplifiers, power amplifiers, etc.
- Power supply:Switching regulators, DC/AC converters, SW regulators, etc.
- Communication:electronic equipment, high-frequency amplifiers, filtering appliances, sending circuit
- Office automation equipment,motor drivers, etc.
- AutomotiveElectronic regulators, igniters, power controllers, etc.
- LEDLamps and lighting.
With the promotion energy-saving lamps, various efficient and brilliant LED lamps are greatly welcomed by the market, and the aluminum substrates used in LED lamps have also begun to be applied on a large scale.
The Aluminum PCB Manufacturing process
Aluminium PCB board for led
The aluminum substrate production process is as follows.
1. Cutting lamilate
- The process of material opening-cutting
- The purpose of cutting
- Cut large-size incoming materials to the size required for production
- Precautions for cutting
① Open the first piece to check its size
② Look for scratches on aluminum surface and copper surface
③ Pay attention to the delamination and the front of the board
- Drilling process
- Pinning-drilling-board inspection
- The purpose of drilling
- Positioning and drilling of plates provides assistance for subsequent production processes and customer assembly
- Precautions for drilling
① Check the number of holes and the size of holes
② Avoid scratches on the sheet
③ Check the front of the aluminum surface and the deviation of the hole position
④ Check and replace the drill bit in time
⑤ The drilling is divided into two stages: first, after cutting, drill the peripheral tool hole; second, drill tool hole in the unit after solder mask
3. Dry/wet film Developing
- Dry/wet film developing process
- Grinding board-filming-exposure-development
- The purpose of dry/wet film developing
- Show the parts needed to make the circuit on the sheet
- Precautions for dry/wet film developing
① Check whether there is an open circuit after development
② Check whether there is deviation in the development registration to prevent the occurrence of dry film breakage
③ Pay attention to the defective circuit caused by scratches on the board surface
④ Ensure that no air remains during exposure to prevent poor results
⑤ After exposure, keep still for more than 15 minutes before developing
4. Acid/alkaline etching
- Acid/alkaline etching process
- Etching-film removal-drying-board inspection
- Purpose of acid/alkaline etching
- After imaging the dry/wet film, keep the required circuit parts and remove the excess parts other than the circuits. Pay attention to the corrosion of the etching solution on the aluminum substrate during acid etching.
- Precautions for acid/alkaline etching
① Note whether the etching is not clean, or that the etching is excessive
② Pay attention to line width and line thinness
③ Ensure that there is no oxidation or scratching on the copper surface
④ Remove the dry film to clean
5. Silk screen solder mask, characters
- Silk screen solder mask and character process
- Silk screen-pre-bake-exposure-development-characters
- The purpose of the silk screen solder mask and characters
① Anti-solder: protect the circuit that does not need to be soldered, and prevent the entry of tin from causing a short circuit
② Characters: play a role in marking
- Precautions for screen printing solder mask and characters
① Check whether there is debris or foreign substances on the board
COB aluminum substrate
COB aluminum substrate
② Check the cleanliness of the screen
③ Pre-bake for more than 30 minutes after screen printing to avoid bubbles in the line
④ Pay attention to the thickness and uniformity of the silk screen
⑤ After pre-baking, the board should be completely cooled to avoid staining the film or destroying the gloss of the ink surface
⑥ Place the ink face down when developing
- The process of V-CUT and gong board
- V-CUT-gong board-tear off the protective film-except for the front
- The purpose of V-CUT and gong board
① V-CUT: Connect the single PCS circuit to the whole PNL plate cutting and leave a small part to facilitate packaging and taking out
② Gong board: remove the excess part of the circuit board
- Precautions for V-CUT and gongs
① Pay attention to the size of the V, incomplete edges, and burrs during V-CUT
② Pay attention to burrs and skewed gong knives, check and replace gong knives in time
③ Finally, avoid scratches on the board when removing the front
7.Test, organic solderability preservative (OSP)
- Test, OSP process
- Line test-withstand voltage test-OSP
- Test, the purpose of OSP
① Line test: check whether the completed line works normally
② Withstand voltage test: check whether the completed circuit can withstand the specified voltage environment
③ OSP: Let the circuit be better soldered
- Test, OSP precautions
① Distinguish between qualified and unqualified products after testing
② Take care of the placement after finishing OSP
③ Avoid line damage
8. Final quality control (FQC), final quality assurance (FQA), packaging, shipping
① FQC conducts full inspection and confirmation of the product
② FQA conducts sampling verification
③ Pack and ship to customers as required
① FQC pays attention to the confirmation of the appearance during the visual inspection and makes a reasonable distinction
② FQA conducts random inspections to verify FQC inspection standards
③ Confirm the packaging quantity, avoid mixing boards, wrong boards, and packaging damage
Aluminum PCB testing Items
Aluminum pcb test
- Experimental conditions
- Typical value
- Performance parameter
- Peel strength
- Solder resistance
- No layering, no bubbles
- Insulation breakdown voltage
- Thermal resistance
- Cooked impedance
- Thermal conductivity
- Surface resistance
- Volume resistance
- Dielectric constant
- Dielectric loss
- Flame resistance
- Insulation thickness: 75 um±% Conductor thickness: 35um±10%
- Metal plate thickness: 1.0mm±0.1mm
※ The above thickness is only the thickness of the adhesive layer, not including copper foil and copper plate.
Aluminum PCBs are generally stored in a dark and dry environment. Most aluminum PCBs are prone to dampness, yellowing, and blackening. Generally, they should be used within 48 hours after opening the vacuum package.
Types of Aluminum Substrates
The commonly used metal aluminum-based plates for aluminum substrates mainly include 1000 series, 5000 series, and 6000 series. The basic characteristics of these three series of aluminum materials are as follows:
① 1000 series represents 1050, 1060, 1070. 1000 series aluminum plating is also called pure aluminum plate. Among all series, the 1000 series contains the most aluminum, and the purity can reach more than 99.00%. Because it does not contain other technical elements, the production process is relatively simple and the price is relatively cheap. It is the most commonly used series in conventional industries. Most of the products circulating on the market are 1050 and 1060 series. The 1000 series aluminum plate is based on the last two digits to determine the minimum aluminum content of this series. For example, the last two digits of the 1050 series are 50. According to the international brand naming principle, its aluminum content must reach 99.5% or more to be a qualified product. In my country's aluminum alloy technical standard (GB/T3880-2006), it is also clearly stipulated that the aluminum content of 1050 reach 99.5%. For the same reason, the aluminum content of the 1060 series aluminum plate must reach 99.6% or more.
② 5000 series represents 5052, 5005, 5083, 5A05 series. The 5000 series aluminum plate belongs to the more commonly used alloy aluminum plate series, the main element is magnesium, and the magnesium content is between 3-5%, which is also called aluminum-magnesium alloy. The main features are low density, high tensile strength, and high elongation. In the same area, the weight of aluminum-magnesium alloy is lower than other series, so it is often used in aviation, such as aircraft fuel tanks. In addition, it is widely used in conventional industry. Its processing technology is continuous casting and rolling, which belongs to the hot-rolled aluminum plate series, so it can be used for oxidation deep processing. In my country, the 5000 series aluminum sheet is one of the more mature aluminum sheet series.
③ 6000 series represents 6061, mainly containing magnesium and silicon, so the advantages of 4000 series and 5000 series are concentrated. 6061 is a cold-treated aluminum forging product, suitable for applications with high requirements for corrosion resistance and oxidation. It boasts good workability, excellent interface characteristics, easy coating, and good processability.
The general characteristics of 6061: excellent interface characteristics, easy coating, high strength, good workability, and strong corrosion resistance. Typical uses of 6061 aluminum: aircraft parts, camera parts, couplers, ship parts and hardware, electronic parts and connectors, etc.
Considering the texture, hardness, elongation, chemical properties, and price of the material itself, aluminum substrates are generally commonly used in 5000 series aluminum alloy 5052 aluminum plates.
Classification of Aluminum PCB
According to the process: HASL/LF Aluminum PCB, aluminum OSP Aluminum PCB, Immersion Silver Aluminum PCB , Immersion Gold Aluminum PCB, etc.
According to use : street lamp aluminum PCB, fluorescent lamp aluminum PCB, LB aluminum PCB, COB aluminum PCB, Packaging aluminum PCB, bulb aluminum PCB, power supply aluminum PCB, automotive aluminum PCB and so on.
RAYMING has been offering aluminum PCB manufacturing services for over ten years. Our full feature aluminum circuit board–making capabilities and value-added options, including Free DFM Check, allow you to get high-quality aluminum PCBs fabricated within budget. Aluminum PCBs printed by RAYMING are widely used for LED lighting, power equipment, and automotive systems.
Aluminium PCB for led
Metal Core PCB Materials and Thickness
The metal core of the thermal PCB can be aluminum (aluminum core PCB), copper (copper core PCB or a heavy copper PCB), or a mixture of special alloys. The most common is an aluminum core PCB.
The thickness of metal cores in PCB base plates is typically 30 mil - 125 mil, but thicker and thinner plates are possible.
Metal Core Printed Circuit Board (MCPCB) copper foil thickness can be 1 - 10 oz.
RayMing Aluminum PCB Capacity
RayMing can produce 1-Layer, 2-Layer,4-Layer, and 6-layer Aluminum PCBs. Multilayer aluminum PCBs are mainly used by high-power industrial products like outdoor LED screens.
Solder mask colors
White & Black. We can provide super white color for LED PCBs to improve the LED lumen.
The following table presents some of our Aluminum Core materials:
|Items||Performance Index (Measured value)|
|Peeling strength (n/mm)||1.8|
|Insulation resistance (ω)||>1*10 g|
|Breakdown voltage (vdc)||>2 k|
|Soakable soldering (°C/m)||280°C / 260°C, 1 min, no bubble & delamination|
|Thermal conductivity (ω/m-k)||>0.8|
|Thermal resistance (°C/ω)||< 1.2|
|Dielectric constant (1mhz)||4|
|Dielectric loss angle (tangent)||0.03|
Check our Aluminum core PCB manufacturing capabilities in the following table:
|Quality Grade||Standard IPC 2|
|Number of Layers||4 - 24layers|
|Order Quantity||1pc - 10000+pcs|
|Build Time||2days - 5weeks|
|Material||Aluminum core (Domestic 1060), Copper core, FR-4 covering|
|Board Size||Min 6*6mm | Max 610*610mm|
|Board Thickness||0.8mm - 5.0mm|
|Copper Weight (Finished)||0.5oz - 10.0oz|
|Solder Mask Sides||As per the file|
|Solder Mask Color||Green, White, Blue, Black, Red, Yellow|
|Silkscreen Sides||As per the file|
|Silkscreen Color||White, Black, Yellow|
|Surface Finish||HASL - Hot Air Solder Leveling
Lead Free HASL - RoHS
ENIG - Electroless Nickle/Immersion Gold - RoHS
|Min Annular Ring||4mil|
|Min Drilling Hole Diameter||6mil|
|Other Techniques||Countersink holes