If you want
LED products to play the best performance, not only need to start from the design, but also the chemical reactions around the
video wall led screen products are also one of the factors that need to be considered. If the chemical reaction is not handled properly, it is likely to cause irreversible damage to the performance of the LED. This article will start from the perspective of chemical reactions, to tell you about the chemical reactions that should be paid attention to in LEDs.
1. The workshop environment is best guaranteed to be below 30 degrees and humidity within 40%RH-60%RH.
A temperature and humidity meter can be used to monitor environmental changes, and gloves or finger cots should be worn when touching the LED inspection. After the packaging bag is opened, it should be sealed in time to prevent oxidation of the feet.
2. Avoid exposing the LED to the acidic (PH<7) workshop environment.
For other LED assembly supporting materials purchased, the manufacturer can be required to provide the MSDS report (Material Safety Data Sheet) of the raw material to confirm whether it contains sulfur, (such as MCPCB boards, rubber gloves, rubber bands, and sulfur soaps contain sulfur. ), halogen-based substances (such as glass glue, low-end two-component resin glue), to prevent chemical or physical reactions with LED materials, such as LEDs that are in contact with sulfur-containing or halogen-containing substances or stored in an acidic environment. It is easy to cause corrosion of the silver-plated layer of LED products, and variations in the properties of LED silica gel and phosphor materials, resulting in the failure of LED photoelectric performance.
3. The user end must pay special attention to the protective treatment of sulfur in the production process, and select quality-assured MCPCB boards, solder paste and other auxiliary materials (without sulfur, halogen, etc. or whose content is lower than the safety standard).
From the EDS analysis of MCPCB boards in several cases in the past, it can be seen that many boards produced on the market have different levels of sulfur residues, although MCPCB manufacturers will clean the boards during the process to eliminate sulfur and sulfur. Acid chemical solvent residues, but it is difficult to completely eliminate them in ordinary production processes. For this, it is necessary to carry out quality control on the residual sulfur content of MCPCB boards. Generally, the maximum sulfur (S) content on MCPCB copper foil does not exceed 0.5% as the upper limit standard.
4. The following temporary measures can be used to prevent LEDs from being patched (SMT):
A. The characteristics of sulfur are more active at high temperature. Before surface mounting, the MCPCB board can be pre-passed through a high-temperature reflow oven (about 230 degrees) before surface cleaning (medical alcohol, etc.) can be used (if conditions are not allowed) Next, the MCPCB surface can be cleaned directly before mounting) to reduce the sulfur content of the MCPCB pad and surface layer.
B. Regularly clean the reflow oven and dehumidification oven to reduce the content of sulfur or halogen;
Control the workshop environment of LED or LED-containing components during welding, handling and application, and control the content of sulfur or halogen.
5. During the welding and processing of LEDs, please do not use auxiliary materials containing sulfur or halogens (such as rubber gloves, rubber finger cots, rubber bands, filler glass glue, hot melt adhesives, etc.) to touch the LEDs.
Chemical problems are not like if there is an error in the LED lighting circuit, it can usually be corrected by replacing the device, but it will cause irreversible damage to the circuit. Therefore, we need to pay special attention to these issues when designing.
The above 5 points are some chemical issues that LED designers need to pay attention to. Chemical problems are not like in the LED lighting circuit, if there is an error, it can usually be corrected by replacing the device, but it will cause more irreversible damage to the circuit. Therefore, we need to pay special attention to these issues when designing.
