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Some factors affecting the life of LED display
- Aug 25, 2018 -

Some factors affecting the life of LED display


The LED display has the advantages of high brightness, flexible installation, low energy consumption, etc., which makes it widely applicable to places with flexible display area and long viewing distance. At present, there are nearly a thousand LED display manufacturers in China, but there are less than 100 production scales (Easy is one of them).

For LED displays, their lifetime can be divided into economic life, technical life, service life and average life. The economic life of a product (also known as the value of life) is determined by the maintenance and depreciation of the product, usually based on the minimum annual average cost of use, the life of the product; the economic life is used to determine the most The old age and the best update timing; the technical life is the period in which the product has a technical value, that is, the length of the technical life is determined from the beginning of use of the product to the replacement of the new technologically advanced equipment. In the invisible wear rate of the device, in fact, the current technical life of the LED display is generally only 3 years; the service life refers to the time from the use of the product to the complete failure. As an integrated system integrating LED display technology, visual principle, computer technology, video technology and electronic technology, LED display can be divided into independent parts, and each part is replaceable, so in actual use The life of LED displays is quite long, and some can even be decades. Average life (also known as mean time between failures or MTBF) refers to the time elapsed between two failures. It is a statistical average, the determination of MTBF value, usually using theoretical statistics and empirical statistics, theoretical statistical methods. Accumulated averaged data based on actual conditions of devices, components, and constraints. Empirical statistics are cumulative average data based on destructive records from factories or laboratories. Regardless of the method used, the reliability of the product changes regularly. Taking the failure rate as an example, its curve over time is like a bathtub, which is commonly referred to as the "bathtub curve". From the bathtub curve, the life of the product can be divided into three stages: early life; life; loss life.

Electronic product manufacturers generally eliminate early failures by testing, aging, screening, etc., and then provide them to customers. When the service life period is over, the product is about to enter the high-risk period of failure, and needs to be scrapped or updated.

The impact of environmental factors on product life

1. The impact of temperature on product life

The failure rate of any product during the service life and only under the right working conditions is very low, and the LED display is an integrated electronic product, which is mainly composed of a control board, a switching power supply, a light-emitting device, etc. with electronic components attached thereto. Composition, and the lifetime of all of these is closely related to the operating temperature. If the actual operating temperature exceeds the scope of use specified by the product, not only will the lifespan be shortened, but the product itself will also be severely damaged.

2. The impact of dust on product life

To maximize the average life of LED displays, the threat of dust cannot be ignored. Working in a dusty environment, the printed board absorbs dust, and the deposition of dust will affect the heat dissipation of the electronic components, which will cause the temperature of the component to rise, resulting in a decrease in thermal stability or even leakage, which may cause burns in severe cases. . In addition, dust can also absorb moisture, corrode electronic circuits, and cause short-circuit failure. Although the volume of dust is small, the harm to the product cannot be underestimated. Therefore, it is necessary to clean up regularly to reduce the probability of failure. When cleaning the dust inside the display, remember to disconnect the power supply and handle it carefully.

3. The impact of humidity on product life

Although almost all LED displays can work in a 95% humidity environment, humidity is an important factor influencing product life. The humid gas enters the inside of the IC device through the joint surface of the package material and components, causing the internal circuit to oxidize and break the circuit, and the high temperature during the group soldering process causes the humid gas entering the IC to be thermally expanded to generate pressure, so that the plastic is Internal separation (delamination) on the chip or lead frame, wire bond damage, chip damage, internal cracks and cracks that extend to the surface of the component, and even component bulging and bursting, also known as "popcorn", which leads to assembly Rework or even scrapped. More importantly, those invisible and potential defects will be incorporated into the product, causing problems in the reliability of the product. Reliability improvements for wet environments include the use of moisture barrier materials, dehumidifiers, protective coating closures, and the like.

4. Influence of corrosive gases on product life

Humidity and salty air environments can cause degradation of system performance because they can exacerbate the corrosive effects of metal parts and also contribute to the generation of galvanic cells, especially when different types of metals are in contact. Another detrimental effect of moisture and salty air is the formation of a film on the surface of non-metallic parts that causes the insulation and dielectric properties of these materials to degrade, thereby forming a leak path. The absorption of moisture by the insulating material can also cause an increase in the volumetric conductivity and dissipation factor of the material. Reliability improvements for wet and salty air environments include the use of hermetic seals, moisture barrier materials, dehumidifiers, protective coatings/caps, and reduced use of different types of metals.

5. Influence of electromagnetic radiation on product life

The interference of radio frequency radiation on electronic systems generally comes from two sources. One way is that the electrical noise of the radiation field interferes directly into the system. Experiments show that when the field strength reaches 5V/m, the system will definitely make an error. The electromagnetic interference is enough to change the value of the CPU program counter PC, so that the microcomputer erroneously "jumps out" the program being executed, especially for small signal circuits. The memory does not work properly when the field strength is 15V/m. Another way of RF interference is introduced through the power supply. The power line of the outer frame is equivalent to the receiving antenna, and the radiation interference is introduced into the system. When such interference is serious, the power of the system itself can be burned.

6. The impact of vibration on product life

Electronic equipment is often subjected to environmental shocks and vibrations during normal use and testing. This environment can cause physical damage to components and structural parts when the resulting mechanical stress caused by the deflection exceeds the allowable working stress of the component parts.

7. The impact of load on product life

Whether it is an integrated chip or an LED tube or a switching power supply, whether it is operated under a rated load, the load is also an important factor affecting the life. Because any component has a fatigue damage period, taking the power supply as an example, the brand power supply can output 105%~135% of power. However, if the power supply is operated under such a high load for a long time, the aging of the switching power supply will be accelerated. Of course, the switching power supply does not necessarily fail immediately, but it will quickly reduce its life.

Review

From the impact of various environmental factors on product reliability indicators, it can be seen that each environmental factor experienced by the product during the life cycle needs to be considered in the design process. This will ensure that sufficient environmental strength is incorporated into the reliability design. Of course, improving the product's use environment and regular maintenance of the product can not only eliminate hidden troubles in time, but also improve product reliability and extend the average life of the product.


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