1. The motherboard shield must not have too many unnecessary openings and gaps. Explanation: An ideal shielded shield is free of any openings or gaps. The shielded interference signal is radiated to the inner surface of the shield. If it is an ideal shield, the interference signal is shielded by 100% without any leakage. However, if the length of the shield opening and gap is greater than or equal to an integral multiple of the half wavelength of the electromagnetic wave, the leakage of the electromagnetic wave is maximized. For a 1 GHz (300-mm wavelength) interference signal, when the gap and the opening length are less than 150 mm (half wavelength), the 1 GHz interference signal starts to be attenuated. If you want to attenuate 20DB, then the gap length should be less than 15mm (1/10th of 150mm, 20 log 10=20db.) If you want to attenuate 26Db, then the gap length should be less than 7.5mm (15mm of 1/2, 20 log 2 = 6db If you want to attenuate 32db, then the gap length should be less than 3.75mm. A better shield shielding effectiveness is required to reach 30-40db. In the figure below, the openings and gaps are large, and electromagnetic leakage is very large. 2. There must be no gaps in the four corners of the main board shield cover, and they must be lapped or riveted well. Explanation: According to the above analysis, there are no gaps in the four corners of the shield, such as the two shields on the right. The products on the left are those of our company. To compare the corners of two shields, one is to consider the corner gaps, and the other is to not consider the corner gaps. If the shield has good shielding effectiveness, the corner gap must be handled properly. 3. The shield opening on the disc exit of a DVD movement cannot be too large. Explanation: Too much opening of the shield cover at the exit of the movement of the disc causes the noise on the main board, the noise on the DVD board and the movement to radiate through these relatively large openings. The mask should be made to leave only one disc exit as shown in the figure on the right. Thick Wall Stainless Steel Pipe Thick Wall Stainless Steel Pipe,Thick Wall Ss Pipe,Welding Think Wall Stainless Steel Tubing,Decorate Seamless Ss Thick Wall Pipe ShenZhen Haofa Metal Precision Parts Technology Co., Ltd. , https://www.haofametals.com
