COB light source use precautions
Unlike traditional SMD packages, COB (Chip on Board) LED technology involves directly mounting one or multiple LED chips onto an aluminum substrate. This design significantly improves heat dissipation and enhances the overall performance of the LED. Due to its low thermal resistance, cost-effective assembly, and excellent light uniformity, COB LEDs have gained widespread popularity in the lighting industry.
Important Usage Precautions for COB Light Sources
Static Electricity Protection:
COB light sources are highly sensitive to static electricity. Proper anti-static measures must be taken during handling and installation. Static discharge can exceed the maximum ratings of the device, potentially causing permanent damage. To prevent this, ensure grounding resistance is below 10 ohms. Use anti-static wrist straps, mats, overalls, gloves, and grounded soldering tools. Always ground your soldering iron properly before use.
Soldering Guidelines:
For manual soldering, it is recommended to use a low-power soldering iron (under 20W), with a temperature not exceeding 300°C and a soldering time limited to 3 seconds. For reflow soldering, follow the temperature curve provided in the figure. After soldering, allow the product to cool to room temperature before handling.
Cleaning Procedures:
After soldering, clean the product using isopropyl alcohol or denatured alcohol (95% or higher). The cleaning process should be done at 50°C for up to 30 seconds or at 30°C for 3 minutes. Ultrasonic cleaning should not exceed 300W.
Additional Notes:
Avoid touching the gel part of the LED at all times to prevent surface defects or failure. Cree introduced the XLamp® CXA2011 in 2011, followed by several other models including CXA1304, CXA1310, CXA1507, CXA1512, CXA1816, CXA1820, CXA1830, CXA1850, CXA2520, CXA2530, CXA2540, CXA2590, CXA3050, CXA3070, and CXA3590, totaling 15 COB series products.
The new XLamp® CXA Series COB integrated light sources offer numerous benefits, such as easy assembly, high lumen output (5,000–10,000 lm), and compatibility with various applications like lamps, track lights, downlights, spotlights, outdoor lighting, and high-ceiling lighting. This article focuses on proper handling of the XLamp® CXA series during manufacturing.
Key Handling Considerations for XLamp® CXA Series High-Power COB Light Sources
To ensure optimal performance, Cree recommends the following when working with the XLamp® CXA series:
- Avoid applying mechanical stress to the LED.
- Never touch the optical surface with fingers or sharp objects. When handling with tweezers, avoid touching the lens to prevent contamination or damage.
- Always take anti-static measures, such as wearing an electrostatic ring or connecting a resistor to the power supply.
- Use powder-free latex gloves when handling the COB light source.
Mounting the XLamp® CXA Series COB Integrated Light Source
Efficient thermal management is essential. Mount the COB source on a suitable heat sink based on voltage, current, and environment. A thermally conductive epoxy or thermal grease (TIM) is commonly used between the COB and the heat sink. Keep the TIM layer as thin as possible to minimize voids. For certain models, a reflective TIM pad may be used, but darker materials might slightly reduce light output.
CXA15xx, CXA25xx, and CXA3050 models are housed in ceramic substrates and can be mounted with epoxy or LED connectors. Many manufacturers, including Molex, TE Connectivity, IDEAL, and United States Up to Optical, have developed connectors to simplify installation and replacement.
Thermal paste offers good conductivity but can be harder to adjust once applied. Connectors, on the other hand, allow for easier assembly, electrical connection, and replacement. Choose based on cost, practicality, and design needs.
For the CXA2011, securing it with two diagonal screw holes or a connector is recommended. Use a 4-40 or M2.5 screw with a torque of around 45 N·cm to avoid damaging the LED array.
Soldering Instructions for XLamp® CXA Series COB Light Sources
Wire bonding is suitable for the XLamp® CXA Series. Cree recommends using a soldering iron with a tip size of 1.8 mm. Due to variations in heat sinks, LEDs, and soldering methods, specific recommendations are not provided. After soldering, allow the device to cool to room temperature before further processing. Avoid exposing the LED to temperatures above 350°C during soldering.
When soldering wire connectors directly to the COB, follow these steps:
- Solder the contact pads evenly.
- Apply appropriate solder to the wire and connect it to the COB.
- Ensure sufficient strain relief to prevent pulling the pads.
Cree recommends using “no-clean†solder paste, such as SnAgCu or SnAg, to eliminate the need for post-reflow cleaning.
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