Everwide newsletter No.93

A customer found that some photoelectric components filled with epoxy resin will crack during the cooling process after heating and curing, and the defect rate is about 1% (left picture). We couldn't think of the reason, so we cut this part from the middle with a slow-cutting machine. We found that the thickness of the epoxy resin on both sides of the normal part is very even after cutting, about 1.5mm (right picture). The thickness on both sides of the cracked part is very uneven. One side is thick and the other is thin. The thick part is 1.9mm and the thin part is only 1.1mm (right picture). We speculate that because the thickness of the resin is too different, the shrinkage is uneven during the cooling process, and excessive stress causes cracks. After we communicated with customers, they found that some parts were not placed horizontally during the heating and curing process, resulting in uneven resin thickness. After the level adjustment, the parts no longer cracked.

─Author: Dr. Ming-Xu Li / Photography: Ms. Jia-Ying, Qiu Everwide Chemical

If you have visited Everwide Chemical, you might be curious where is the "guard"? Unlike ordinary companies, we have no guards. In the early days, the staffing of the organization was simple, so we don't need the guards. Up to now, the number of employees at Everwide is more than one hundred, and we still have no guards. Everyone will ask, what should we do for everyone’s safety at night? Since Everwide Chemical has staff dormitories, and there are people staying in the company every night, if the company has an accident, the people will be responsible for reporting. When people were sleep, our best guards, the dogs will protect us. Dogs are the most loyal friends of humans, so we have kept five "ferocious dogs" in the factory. Each of them is very powerful. Among them, the Tibetan Mastiff mixed breed "Dabao" has the deepest experience and the longest service. In addition to being responsible for the night guard mission of Everwide Chemical, they also helped the neighbor on the opposite side to relieve the thief crisis. When you visit Everwide, there is no need to worry that the dogs will attack you. Because, during the day, they will return to the cage to rest, waiting for night work tasks and delicious food.

In Everwide Chemical Newsletter-Issue 91, we mentioned the processing method when epoxy resin is crystallized. Below we introduce several situations where epoxy resin may crystallize: 1. Epoxy resin crystallizes fastest in an environment of 10°C. 2. The lower the chlorine content of the resin, the narrower the molecular weight distribution, and the higher the purity, the easier it is to crystallize. 3. There are some diluents that are particularly easy to crystallize epoxy resins, such as BGE. 4. There are some chemicals that will induce the crystallization of epoxy resin, such as BPA. 5. Dust may also become the nucleus of epoxy resin crystals and induce crystallization. 6. The filler may also accelerate the crystallization of epoxy resin. The above are all kinds of conditions that easily cause the epoxy resin to crystallize. Some epoxy resins are easy to be granular due to the composition, and even the whole will become hard. The epoxy resin at this time is not broken but crystallized. Regarding the crystallization treatment of epoxy resin, please refer to the detailed explanation of the 91st issue.

The Internet news a while ago was discussing how to calculate such a formula. Based on years of "experience", I immediately calculated the answer to "1", but the true answer is "9". According to a certain mathematics teacher, the calculation of this formula should be from left to right, that is to say, 6 divided by 2 first calculate 3, and then calculate 2+1=3 in the brackets, and finally, 3×3=9 is the final answer. My "experience" is to calculate 2(2+1)=6 first, which violates the left-to-right calculation principle, so the answer is wrong. Whether it is 1 or 9 is not a brain teaser, so you can't say the result casually. If the teacher is right, then I would like to ask whether 1÷2y in the math formula of junior high school should be interpreted as 1÷2×y=0.5y or 1/(2y) according to the "left to right" rule. The results of the two calculations are completely different. "Arithmetic" is just a tool, the purpose is to complete the work of calculation. As long as the goal can be achieved, moderate simplification will not cause trouble, so many arithmetic symbols, such as "×" or "()" are omitted. Deliberately looking for problems, on the contrary, makes people feel a sense of deliberate existence. No matter what others say, I still insist on 6÷2(2+1)=1.

─Author: Dr. Ye-Xu, Li Everwide Chemical