Issue link: https://iconnect007.uberflip.com/i/1143487
JULY 2019 I PCB007 MAGAZINE 35 After the implementation of the three chang- es in design variables, the effect to the failure rate needed to be verified in terms of whether the system can survive during the severe of shock in the transportation and handling pro - cesses. Two transportation routes were cho- sen: from Fushan, China, to Sezimovo, Czech Republic, through the China and Russia bor- der by train, and a return sea trip through the Mediterranean, Arabic, and South China Seas. As shown in Figure 9, a shock gravita - tional force measurement device was embed- ded in the shipping box of the computer serv- er to record the acceleration and direction of shock in real-time in large stationary or mov- ing systems in transportation and transferring process. The data collected can be used to calcu- late the shock energy level ΔV. The compari- son between the value of ΔV and the criterion can be used to judge whether the shock can cause poor contact problems in transportation and transferring process. At the same time, the maximum temperature and humidity were measured by temperature sticker and humid- ity sticker to compare to the reading from the shock measuring device. Improvement Effect Verification A lab drop test with extreme conditions was performed on a boxed computer server system to simulate the harsh transportation process (Figure 10). The test setting included a 250-Hz filter frequency and a drop height of 610 mm for the packaged weight of 16.42 Kg. In the test, the accelerometer was installed in the box and used to record the acceleration and dura- tion along X, Y, and Z axes when the system was going through 10 multiple corner-edge- face drop tests. After the lab test and road test, the system would go through normal boot-up and inspection to see if any accessories were loosened. Then, the package box was checked, and humidity and temperature numbers on stickers were recorded. The maximum shock energy from field mea- surements and lab tests were then calculated based on Equation 1 where A is the peak ac- celeration of nominal pulse in g and D is the duration of the nominal pulse in 1/ms [2] . If the total energy level from the lab drop test on the product is larger than from real transportation and handling stress, then the package design Figure 9: A shock gravitational force measurement device embedded in the shipping box. Figure 10: The 10 lab corner-edge-face multiple drop tests to emulate transportation stress.