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Everwide Newsletter No.212

Experiment § Wire drawing created by viscosity change

The customer uses a dispenser to apply UV resin on the four corners of the chip, and after exposure and hardening, it is used for fixing the PCB board and the chip (Figure 1, called Corner Bound). When dispensing, the dispensing machine moves very fast. If the adhesive has a wire drawing phenomenon (Figure 2), it will leave the circuit board's glue and cause malfunction. The main reason for the wire drawing phenomenon is the decline of the resin's thixotropy, especially after the dispensing process has been carried out for a while. Figure 3 shows the characteristics of a very typical thixotropic fluid: Point A represents the high viscosity of the resin at the very low speed of the viscometer. As the speed increases, the viscosity decreases (point B). If the speed is reduced at this time, the viscosity will rise again (point C). Point C and Point A are sometimes very close, which means that the adhesive is allowed to stand still after the hose has moved for a while, and the viscosity is almost the same as before; in this case, it may not have a drawing. The relatively large difference between the viscosity of point D and point F in Figure 4 means that the adhesive is allowed to stand after the hose has moved for a while, and the viscosity has decreased significantly; this situation is more likely to cause wire drawing as the dispensing time is extended. In summary, thixotropy is related to shear force and also to action time.

─ Author: Mr. Yu-Ren, Chen


Activity § Add safety net

Many tin roofs are composed of corrugated tin plates and transparent lighting covers to enhance the brightness of the work area. The transparent skylight panel is made of plastic material, and it is easy to become brittle after exposure to wind and sun for many years. According to reports, there are often cases of people falling on the roof by accidentally stepping on the skylight panel. To avoid similar accidents, we specially installed safety nets under the skylight panel. Annual roof cleaning, construction, and maintenance can provide an extra layer of protection. Also, many shelves, stairs, and railings have similar gaps on the sides, and there is also a risk of people and goods falling; we are all discussing the installation of safety nets. There is a saying: There is no best, only better. The application of this concept to the safety protection of the working environment really cannot be ignored.


Knowledge § What is a Fixture Time?

Some adhesive data will record the fixture time. Generally, the fixture time is used for adhesives with fast reaction speed, such as UV resin, instant glue, acrylic structural glue, etc.

These adhesives will cure within a few minutes or even a few seconds and are used to fix the substrate quickly. Its measurement method is simple; drop the adhesive on the glass, and then interlock another piece of glass at a certain angle, and shake the two pieces of glass by hand until the glass is fixed and unable to move; this time is the fixture time. The test material is not limited to glass; plastic and metal are both feasible. The viscosity of slow-reacting adhesives slowly rises, and it is difficult to define the exact fixture time, so this test method is seldom used.


Living & Slow Bike Tour of Sun Moon Lake

I am not a person who loves cycling nor received professional training. My friend persuaded me to take a bike tour of Sun Moon Lake; one of the reasons for the action is that CNN once listed the bike path around Sun Moon Lake as the world's 10 most beautiful bike lanes; of course, I should go and see it! (Please click the square pattern link for the original CNN: ■). The itinerary departs from Shuishe Wharf; the gentle breeze is accompanied by the warm winter sun, the lake is sparkling, and fish can be seen jumping out of the water from time to time; it is hard to imagine that the feeling of a slow tour is so different. When taking a break at the Xiangshan Visitor Center, stop by the viewing platform here, and you can enjoy the clear blue lake from an excellent angle. Starting from this attraction and going forward, there is a long physical strength and endurance test. I gritted my teeth through many climbing sections and almost fainted because of my hunger and low blood sugar. The riders continued to cheer each other up along the way, and some riders asked if we need biscuits to replenish physical strength? The strong affection gave me a lot of power to sustain it. We arrived at Yidashao Wharf, comforted my hard work with a big meal. After we were full, we rode to the terminal. Different from the uphill section just now, the downhill section is easy and comfortable, but you need to be careful to meet with large vehicles and pay attention to the timing of braking to slow down; otherwise, you will crash. After a whole day of shocking education, I won the 29KM ring road (please click the link: ■). Seeing this, is your heart moved? Suppose you are limited by time or physical strength by bicycle; in that case, you can also try the simplified route from Shuishe Wharf to Xiangshan Visitor Center to enjoy the beauty of Sun Moon Lake from a different angle, which is relaxing and cozy.

─ Author: Miss Heng-Hong, Li


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