The single - layer aluminum base PCB is essentially a special - type PCB with a structure of "single - layer circuit + aluminum - based support". Structurally, from bottom to top (or from top to bottom, depending on the component soldering - side design), it is divided into three core layers, each with a clear function and working in coordination:
Some single - layer aluminum base PCBs add a "solder - mask layer" on the surface of the copper - foil circuit layer (such as the matte white oil and matte black oil commonly used in LED lighting). The white - oil solder - mask layer can increase the light reflectivity (up to over 90%), reducing the light loss of LED light sources. The black - oil solder - mask layer has certain light - shielding properties, suitable for scenarios sensitive to light interference.
Although the single - layer aluminum base PCB has a simple structure, its technical advantages are concentrated in the three dimensions of "heat - dissipation, process, and cost", precisely matching the needs of medium - and low - power scenarios:
Compared with traditional single - sided FR - 4 boards (thermal conductivity coefficient of only 0.2 - 0.3W/m·K), the heat - dissipation capacity of a single - layer aluminum base PCB is 3 - 10 times higher. The core logic lies in "direct heat conduction to the aluminum base material". Take an LED lamp bead as an example. When a 1W LED is working and soldered on an FR - 4 board, the junction temperature is likely to exceed 85℃ (causing accelerated light decay). However, when soldered on a single - layer aluminum base PCB, the heat is quickly transferred to the aluminum base material through the insulating layer, and the junction temperature can be reduced to below 60℃, significantly extending the LED lifespan (from 20,000 hours to over 50,000 hours). In addition, the "large - area heat - dissipation characteristic" of the aluminum base material does not require additional complex heat - dissipation structures (such as multi - layer heat - dissipation vias), especially suitable for the uniform heat - dissipation needs of "long - strip - shaped and large - area" lighting products like LED tubes and panel lights.
The manufacturing process of a single - layer aluminum base PCB is optimized based on the traditional single - sided board process, without complex processes such as multi - layer lamination and blind/buried vias. The core steps include: ① Pretreatment of the aluminum base material (cleaning, surface passivation to enhance adhesion to the insulating layer). ② Coating of the insulating layer (evenly coating the thermally conductive insulating adhesive on the aluminum base material and forming the insulating layer through high - temperature curing). ③ Copper - foil lamination (pressing the copper foil and the insulating layer together under high - temperature and high - pressure to ensure the bonding strength). ④ Circuit fabrication (photolithography and etching to form conductive circuits). ⑤ Surface treatment and solder - mask layer printing. ⑥ Shape processing (cutting and drilling to meet installation requirements). The entire process has fewer procedures (only 1/3 of that of multi - layer aluminum base PCBs), a high yield (the industry - average yield is over 95%, higher than the 85 - 90% of multi - layer aluminum base PCBs), and low equipment investment, making it suitable for mass orders of over 100,000 pieces per year.
Under the premise of meeting heat - dissipation requirements, the single - layer aluminum base PCB has significant cost advantages:
- Material Cost: It does not require multiple layers of copper foils and prepregs. The unit price of the aluminum base material (about 20 - 30 yuan/㎡) is lower than the cost of the composite base material of multi - layer boards.
- Processing Cost: The simplified process reduces the processing cost to only 50 - 60% of that of multi - layer aluminum base PCBs (for example, the processing cost of a 1㎡ single - layer aluminum base PCB is about 50 - 80 yuan, while that of a 2 - layer aluminum base PCB is about 120 - 150 yuan).
- Terminal Cost: Without additional heat - dissipation accessories (such as heat sinks and thermal pads), it can reduce the overall cost of end - products (for example, for LED tubes using a single - layer aluminum base PCB solution, the total cost is 15 - 20% lower than the FR - 4 + heat - sink solution).
This characteristic of "low cost + sufficient heat - dissipation" makes it the first choice for medium - and low - power (≤10W) scenarios, such as LED bulbs, small - switch power supplies, and automotive dashboard backlights.
The mechanical strength of the aluminum base material is better than that of the FR - 4 substrate (flexural strength ≥150MPa, while FR - 4 is about 100MPa), with strong vibration and impact resistance, suitable for automotive electronics (such as automotive ambient lights, reverse - radar modules) and industrial control (such as sensor modules) scenarios with vibration requirements. At the same time, the single - layer aluminum base PCB has a wide temperature - resistance range (-55℃ - 125℃, and some high - end products can reach 150℃) and a low water absorption rate (≤0.1%). It is less likely to delaminate or crack in outdoor lighting and high - temperature industrial environments, with significantly higher reliability than traditional FR - 4 substrates.
The application scenarios of single - layer aluminum base PCBs are concentrated in fields with "medium - and low - power, high - heat - generation, and cost - sensitivity". The core scenarios include:
This is the most core market for single - layer aluminum base PCBs, accounting for over 70% of its total usage, specifically including:
- Linear Lighting: LED tubes, light strips (using 1.0 - 1.6mm thick aluminum base material, suitable for long - strip - shaped heat - dissipation. The solder - mask layer is mostly white oil to improve light efficiency).
- Surface - light - source Lighting: LED panel lights, ceiling lights (using 2.0 - 3.0mm thick aluminum base material for large - area uniform heat - dissipation to prevent overheating in the middle area of the panel light).
- Low - power Lighting: LED bulbs, spotlights (using 0.8 - 1.2mm thin aluminum base material, balancing heat - dissipation and lightweight, reducing the weight of the lamp).
Suitable for small - power supplies with an output power ≤10W, such as:
- Switching Power Supplies: Mobile - phone chargers, router power supplies (the single - layer aluminum base PCB can quickly dissipate the heat of the power chip, preventing overload protection caused by chip overheating).
- LED Drive Power Supplies: Integrated with LED lamp beads on the same aluminum base PCB ("lamp - drive - integrated" design), simplifying the lamp structure and reducing costs.
The "low - power, non - core" modules in automotive electronics, such as:
- Automotive Lighting: Ambient lights, dashboard backlights, reading lights (the aluminum base PCB is vibration - resistant, suitable for the bumpy environment during vehicle driving).
- Sensor Modules: Reverse - radar sensors, temperature sensors (wide temperature - resistance range, adapting to the temperature fluctuations in the engine compartment and vehicle cabin).
- Industrial Sensors: Signal - amplification modules of temperature and pressure sensors (the heat - dissipation of the aluminum base PCB can ensure the stable measurement accuracy of sensors).
- Consumer Electronics: Control and display modules of small home appliances (such as coffee - machine indicator lights, air - purifier indicator lights) (low - cost and suitable for mass production).
When choosing a single - layer aluminum base PCB, the following parameters should be paid attention to ensure it meets the actual application requirements:
- Aluminum Base Material Model and Thickness: For medium - and low - power applications with an emphasis on heat - dissipation, choose 1060 aluminum; for applications requiring mechanical strength, choose 5052 aluminum. The thickness is selected according to the installation space and heat - dissipation requirements, usually 1.0 - 3.0mm (0.5 - 1.0mm for limited - space scenarios, and 2.0 - 3.0mm for large - area heat - dissipation scenarios).
- Thermal Conductivity Coefficient of the Insulating Layer: For LED lighting, choose 0.8 - 1.5W/m·K (sufficient and low - cost); for power modules, choose 1.5 - 2.0W/m·K (to deal with high - heat - generation chips).
- Copper - Foil Thickness: Choose 1oz for small currents (≤1A), 2oz for medium currents (1 - 3A), and 3oz for large currents (3 - 5A).
- Surface Treatment: Choose OSP for regular scenarios (low - cost); choose tin - plating/silver - plating for humid environments (good corrosion resistance).
- Solder - Mask Layer Color: Choose white oil for LED lighting (high reflection); choose black oil for light - shielding scenarios; choose green oil for no special requirements (general purpose).
