The impact of environmental factors on product life

However, in some places, the display screen is used for a long time and the display screen is used for a short time. Why? Because the harsh environment will aggravate the aging of the LED display, the environment is an important factor affecting the service life of the display. Below is an analysis of the impact of the environment on the service life of the LED display.

1. Temperature:

(1) If the temperature is too high, the LED display will be completely destroyed:

LED display screens are mostly encapsulated in transparent epoxy resin. If the junction temperature exceeds the solid phase transition temperature (usually 125 ° C), the packaging material will change to rubber and the thermal expansion coefficient will rise sharply, resulting in LED display open and failure, LED display The operating temperature of the screen exceeds the carrying temperature of the chip, which will cause the luminous efficiency of the LED display to be rapidly reduced, resulting in significant light decay and damage.

(2) The increase in temperature will shorten the life of the LED display:

The life of an LED display is characterized by its light decay, that is, the time is long, and the brightness is getting lower and lower until it is finally extinguished. The time at which the LED display's luminous flux decays by 30 is usually defined as its lifetime.

(3) The temperature rise will reduce the luminous efficiency of the LED display

(4) The effect of temperature on the LED display wavelength (light color)

(5) Excessive temperature will limit the maximum injection current of the LED display

2. Dust

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. Wet

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. Corrosive gas

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. Electromagnetic radiation

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. Vibration

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. Load

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.

We only have to minimize the damage of LED screens by various environmental factors and improve the working environment of the display to make our display life increase.