New process for white LED manufacturing: encapsulation through gel-like sheets

In the case where the demand for white LED modules continues to rise due to the use of lighting, Japan's Ideck Corporation (IDEC) has developed a module (pseudo-white LED module) that realizes white light combining blue LED components and yellow fluorescent materials. New manufacturing process (Figure 1)*1. The difference between the new process and the conventional process is that the gel-like silicone resin sheet containing the fluorescent material is attached to the LED element by heating and encapsulating the resin element by encapsulating the LED element on the substrate. Compared to conventional processes, the new process reduces the time required for the packaging process to 1/9, while achieving consistent quality and simplifying equipment.

White LED manufacturing new process

Figure 1: LED module (a) produced by a new process and gel-like resin sheet (b)

White light is achieved by using a combination of a blue LED element and a yellow fluorescent material. The package of the LED element is a gel-like silicone resin sheet (manufactured by Nitto Denko Corporation) containing a fluorescent material.

*1: The way to achieve white light also includes the combination of three primary colors of light - red, green and blue LED elements. However, its use is mostly the light source of the display. In lighting applications, pseudo white LED modules are the mainstream.

Figure 2 shows the comparison between the traditional process and the new process*2. Conventional processes encapsulate LED elements by a liquid resin containing a fluorescent material. First, a "dam" for blocking the outflow of the resin is formed around the LED elements on the substrate and hardened. Then, the liquid resin and the fluorescent material are stirred and poured into the dam on the substrate. Finally, the cast resin is subjected to a heat hardening treatment. The time required for the entire packaging process is approximately six hours.

White LED manufacturing new process

Figure 2: Comparison of traditional and new processes in the packaging process

The conventional process takes about six hours throughout the packaging process (forming the dam and hardening it, stirring the resin and fluorescent material, pouring the liquid resin and hardening it). The new process only requires the gel-like sheet to be attached to the LED component for hardening, so it takes only 40 minutes. Produced by the magazine according to the information of Adek.

*2: In addition, there is a manufacturing process of packaging an LED element by a solid resin sheet containing a fluorescent material. This manufacturing process is easy to stabilize the quality, but it cannot be packaged separately by the solid resin sheet, and it is required to additionally use a liquid resin for packaging, so that the production efficiency is low.

However, in such a manufacturing process, there is a problem that the resin and the fluorescent material are not uniformly mixed, the phosphor is precipitated in the resin, and the amount of the resin to be poured is not large, which causes quality instability, and it is difficult to maintain the quality. If the quality of the packaging process is uneven, chromaticity deviation will occur, which may affect the performance of the LED module.

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