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Everwide Newsletter No.276

Experiment § When epoxy meets SMD

Many LED lamps are filled with epoxy resin to protect the LED and circuit board parts from moisture corrosion and oxidation. Figure 1 is a traditional piranha LED lamp. The packaging material of this LED is epoxy resin. When Silicone-encapsulated surface-mount LEDs become popular, the method of potting epoxy resin to protect lamps needs to be changed (Figure 2). Due to the low height of the SMD, the epoxy resin will flood the light-emitting area. Plus, the hot LED will turn the resin into a brown color when lighting, affecting the brightness and color of the light (Figure 3-4). In addition to the discoloration of the external resin, some components will penetrate into the packaging material of the SMD and discolor inside the SMD (Figure 5). Although some components that penetrate the SMD do not affect the packaging material, but they will react with the chip silver paste, causing the chip itself to change color (Figure 6). In conclusion, when epoxy resin meets SMD LED, you really have to be very careful.

─Author: Su-Huan, Li


Activity § Trip in Xiaoliuqiu

Before the staff travel, colleagues clamored to go to outlying islands - Xiaoliuqiu. This time we went to Vase Rock, Beauty Cave (Sea View Pavilion), Wild Boar Trench, Black Devil Cave, and Geban Beach. Sea View Pavilion is a good place to see the sea and the scenery. The guide shared a knowledge about sea turtles: Sea turtles are omnivorous, so don't stretch out your fingers because you will be bitten. Vase Rock is a popular spot for snorkeling, and it is also a landmark in Xiaoliuqiu. You can watch the scenery in the sea up close; Black Devil Cave is related to the incident on the Lamey island and the cave has undergone a long history of heroic destruction. During the two-day staff travel, we all left many beautiful memories in our minds.


Knowledge § What are functions of TGA?

TGA (Thermogravimetric Analysis) is used to test the relationship between the weight of the test object and the temperature. Many substances change their weight at high temperatures. For example, volatilization of some components, decomposition reactions of some components, cleavage reactions of structures, etc. These products evaporate in the form of gas, causing the weight of the test object to decrease as the temperature increases. In contrast, some substances undergo oxidation reactions at high temperatures, so the weight of the test substance will increase as the temperature rises. For instance, metal aluminum is oxidized to alumina at high temperature. Plot the change in weight of the test object against temperature to obtain a thermogram spectrum. The thermoweight curve has the following functions:1. Use the temperature of 5% weight loss to calibrate the short-term cracking temperature; 2. Obtain the weight retention rate at high temperature, and use this data to estimate the filler content; 3. Overlap different experimental curves and quickly compare whether the composition is variable; 4. Use the cracking kinetic equation to estimate the long-term service life.


Living § Good Book Sharing-The Power of Habit

The decisions that people make every day seem to be thoughtful, but they are not. People are mostly controlled by habits. Behind people's various habits are the rewards that come after the completion of the pursuit of habitual actions. For example, develop the habit of regular exercise to enjoy the comfort after exercise; The habit of eating junk food is based on the satisfaction of appetite. Habits will unknowingly affect people's life, so it is very important to get rid of bad habits and replace them with good ones. Because we need to have a way to withdraw from bad habits, the chance of success is not high if we just rely on inner determination. This book teaches us to analyze habits first, and then discuss changing habits. Obviously, we must first analyze the “reasons” for wanting to get rid of the habit. We must think about the “reward” for doing this action. Then look at what the “reminder” is to perform this action. Maybe at a certain time, a certain place, or when something happens, we will perform bad habits without realizing it. If we know what a “reminder” is, we can change different “habit” actions when it appears, and give this action a new “reward”. For example, addicts always want to smoke after meals. After the meal is a "reminder". In summary, when we find a way, we will be motivated to practice new habits and use them to replace old ones. Habits are not only for individuals, but organizations also have organizational habits. If the organization has positive habits, you don't need to do anything deliberately to achieve good results. This book emphasizes that the conscious establishment of good habits is never subject to bad habits. It is a permanent topic for individuals and organizations. I feel the same, so I would like to share with you.

─Author: Yu- Hsiang, Cheng


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