To get the best performance from LED products , not only do you need to get started with design, but also the chemical reactions that take place around LED products are one of the factors to consider. Chemical reactions, if not handled properly, are likely to cause irreversible damage to the performance of the LED. This article will talk about the chemical reactions that should be noted in LEDs from the perspective of chemical reactions.
1, the workshop environment is best guaranteed to be below 30 degrees temperature, humidity 40% RH-60% RH range.
The temperature and humidity meter can be used to monitor the environmental changes, and gloves or finger sleeves should be worn when inspecting the LEDs. The bags should be sealed in time to prevent oxidation of the feet.
2. Avoid exposing the LED to a workshop environment that is acidic (PH<7).
For other LED assembly materials purchased, the manufacturer may be required to provide the MSDS report (Material Safety Data Sheet) of the original material to confirm whether it contains sulfur. (For example, MCPCB sheet, rubber glove, rubber band, sulfur soap contain sulfur. ), halogen-based substances (such as glass glue, low-end two-component resin glue) to prevent chemical or physical reaction with LED materials, such as LEDs in contact with sulfur or halogen-containing substances or in acidic environments, It is easy to cause corrosion of the silver plating of LED products, and the performance of LED silica gel and phosphor powder materials will be mutated, resulting in 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 MCPCB sheet and solder paste with quality assurance and other auxiliary materials (excluding sulfur, halogen, etc. or the content is lower than the safety standard).
From the EDS analysis of MCPCB sheets in several cases in the past, many plates produced in the market have different levels of sulfur, although MCPCB manufacturers will clean the plates during the process to eliminate sulfur and The residue of the acid chemical solvent, but the ordinary production process is difficult to completely eliminate the clean. For this, it is necessary to carry out quality control on the residual sulfur content of the MCPCB board. Generally, the content of sulfur (S) on the MCPCB copper foil is not more than 0.5%. standard.
4. When the LED is being patched (SMT), it can be prevented by the following temporary measures:
A. The characteristics of sulfur at high temperature are more active. The MCPCB board can be pre-cleaned in a high-temperature reflow oven (about 230 degrees) before surface mounting, and then surface cleaning (medical alcohol, etc.) can be used (if conditions are not allowed) The MCPCB surface can be cleaned directly before mounting to reduce the sulfur content of the MCPCB pads and the surface layer.
B. Regularly clean the reflow oven and the dehumidifying oven to reduce the sulfur or halogen content;
Controls the sulfur or halogen content of the LED or LED-containing components in the shop environment during soldering, handling, and application.
5, LED in the welding and processing, please do not use sulfur or halogen containing accessories (such as rubber gloves, rubber finger cots, rubber bands, filled glass glue, hot melt adhesive, etc.) to contact the LED.
Chemical problems are not like LED lighting circuits. If an error occurs, it can usually be corrected by replacing the device, but it will cause more difficult reversal damage to the circuit. Therefore, everyone needs to pay special attention to these issues when designing.
The above 5 points are some of the chemical issues that LED designers need to pay attention to. Chemical problems are not like LED lighting circuits. If an error occurs, it can usually be corrected by replacing the device, but it will cause more difficult reversal damage to the circuit. Therefore, everyone needs to pay special attention to these issues when designing. I hope everyone can gain something after reading this article.
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