Deep analysis of COB LED temperature distribution mechanism and measurement method

March 06, 2021

The reliability of OFweek's semiconductor lighting LED products is closely related to the temperature of the light source. Since the COB light source is packaged in a high-density chip, the temperature distribution and measurement are significantly different from those of the SMD light source. From the technical level, the temperature distribution characteristics of COB light source and its internal mechanism are introduced, and the commonly used temperature measurement methods are compared.

introduction

COB (Chip-on-Board) packaging technology has received more and more attention in the industry due to its low thermal resistance, high luminous flux density, small color tolerance, and fewer assembly processes. COB packaging technology has been used in IC integrated circuits for many years, but for the majority of luminaire manufacturers and consumers, LED light source is COB package or novel technology.

The reliability of LED products is closely related to the temperature of the light source. Since the COB light source is packaged in a high-density package with multiple chips, the temperature distribution and measurement are significantly different from those of the SMD light source.

Temperature distribution of COB light source

The COB package is to mount the chip directly on the substrate of the light source. When used, the COB light source is directly connected to the heat sink, eliminating the need for SMT surface assembly. In the SMD package, the chip is first mounted on the holder as a device, and the device needs to be mounted on the substrate and then connected to the heat sink.

The schematic diagram of the thermal resistance structure of the two is shown in Figure 1. Compared with the SMD device, the COB thermal resistance is less than the thermal resistance of the solder layer and the thermal resistance of the solder layer when the SMD is used, and the heat of the chip is more easily transmitted to the heat sink.

1

Figure 1: Schematic diagram of thermal resistance structure

1, comparison of common temperature measurement methods

Commonly used temperature sensor types are thermocouples, thermal resistors, infrared radiators, and the like. A thermocouple consists of two different wires that are joined together at one end. The temperature change at the junction causes a voltage change between the other ends. The voltage can be reversed by measuring the voltage. The thermal resistance calculates the temperature by indirectly measuring the resistance by using the mechanism of the resistance of the material as a function of the temperature of the material.

The infrared sensor measures the temperature by measuring the radiant energy emitted by the material. The main features of the three are shown in Table 1.

2

Table 1: Comparison of temperature measurement methods

Thermocouples are inexpensive and the most widely used in the field of temperature measurement. The smaller the probe is, the more sensitive it is to temperature. IEC60598 requires thermocouple probes to be coated with highly reflective materials to reduce the effect of light on temperature measurement. However, if the thermocouple is directly attached to the illuminating surface for measurement, the effect of converting the absorbance of the probe into heat is very obvious, which may result in a high measured value.

Aluminum Profiles Materials and features:
1, the shape led jewelry counter lamp housing are V-shaped, U-shaped and triangle, so the jewelry counters led lamp housing, also known as V-groove, U-groove and triangular-shaped groove;
2, Sichuan and spread of new energy production can be equipped with plug, 90 degree angle, angle of 135 degrees, 180 degrees straight through led jewelry counter lamp housing, 6063 GB of raw materials are all aluminum, high purity aluminum, quality assurance, all through the testing and certification;
3, surface gloss, uniform oxide film, bright color, color uniformity, corrosion resistance;
4, the appearance of fine, beautiful, overall product design scientific and rational, durable;
5, high-pressure tensile aluminum shell, good heat dissipation, and diverse styles.
6, product variety, can be customized according to customer demand.
7, the surface may be anodized, electrostatic spraying, gloss treatment
8, streamlined design, the appearance of multilateral tooth design, increase the cooling area, cooling fast.

Aluminum Profiles

Aluminium Profiles,Aluminum Profile For Curtain Wall,Aluminium Profiles For Windows And Doors,Waterproof Aluminium Profiles

Shenzhen Mingxue Optoelectronics CO.,Ltd , https://www.led-lamp-china.com