Several important communication parameters such as impedance, attenuation, delay and near-end crosstalk attenuation of SAS transmission line are analyzed, and the key points of manufacturing process design and process control are clarified. The factors that may cause the above important parameters to deteriorate in each process are controlled.
In the production process of the insulation process, comprehensive consideration of the factors that affect the quality of the product, the theoretical analysis and the specific equipment and the actual use of raw materials, and finally make a suitable process plan to guide the production of SAS high-speed transmission line insulation process. Because the raw materials and production equipment selected by each production enterprise are different, there are certain differences in practical applications. There are many factors affecting the performance parameters of physical foam insulation, but the main influencing factors are the points mentioned in this paper. In the production process, the main factors can be solved first, and then the secondary factors are adjusted.
Equipment requirements
In the production process of this product, it is necessary to understand two key terms, 1, wrapping, 2, hot melt.
The thickness and overlap rate of the wrapped aluminum foil should be strictly controlled, and the overlap rate of the ordinary wire can meet the requirements in 15-25%, but SAS uses the structure of parallel line pairs, and the anti-crosstalk ability of the line pairs themselves is reduced to zero. In order to ensure the crosstalk attenuation of the near end of the cable, It is generally required that the overlap rate of wrapping is between 30-40%, the process control of the manufacturing process of wrapping is very important, the wrapping quality will affect the non-uniformity of the transmission medium, such as the release of aluminum foil is not smooth and there are aluminum chips, when the blockage to the general degree, the aluminum foil will be pulled off; In addition, if the aluminum foil is not placed smoothly, the debris will be scraped off, and it will adhere to the surface of the core wire very uneven, affecting the uniformity of the transmission medium, resulting in a decline in the transmission performance of the product, especially the impedance and attenuation.
Before the differential pair take-up, the self-adhesive polyester tape needs to be heated to make the hot melt adhesive of the self-adhesive polyester tape melt and bond. The hot melt part adopts the controlled temperature electromagnetic heating preheater, and the heating temperature can be adjusted appropriately according to the actual needs. General preheater installation methods are vertical and horizontal two, the vertical preheater can save space, but the winding pair needs to pass through a large Angle of the guide wheel, in order to enter the preheater, easy to make the insulation core and the relative position of the wrapping tape change, resulting in a decline in the electrical performance of the high-frequency transmission line. In contrast, because the horizontal preheater is in the same straight line with the winding pair, before entering the preheater, the wire pair only passes through a few guide wheels with national straightening function, and the Angle of the winding wire knitting does not change when passing through the guide wheel, which ensures the stability of the phase knitting position of the insulated core wire and the winding tape. The only disadvantage of the horizontal preheater is that it takes up more space and the production line is longer than the winding machine equipped with the vertical preheater.
Therefore, when selecting the equipment, it is necessary to fully consider the equipment capacity and the actual situation of the production workshop. Generally, if the space conditions of the production workshop allow, vertical preheaters can be used for high-frequency communication lines below 5GHZz, while horizontal preheaters are used for high-frequency communication lines with higher frequencies. If the production workshop space is limited, the production of frequent transmission lines above 5GHz can also use vertical preheaters, but relative to horizontal preheaters, the process control is more complex. When wrapping polyester tape, it should be noted that the direction of wrapping should be opposite to the direction of aluminum foil, the overlap rate is stable, and there is no undesirable phenomenon such as warping. Before receiving, it is necessary to heat the self-adhesive polyester tape, the heating temperature should not be too high, the temperature is too low, the hot melt adhesive can not be fully melted, the bond is not strong, and it is easy to have leakage adhesion phenomenon, such as leakage adhesion phenomenon, the product may not be found unqualified in the initial test stage, but after moving in the later use process, it is likely to cause loose deformation of wrapping. Leading to the polyester charged aluminum foil layer has an opening phenomenon, resulting in electromagnetic wave leakage, affecting the shielding effect, resulting in product scrap, and once this unqualified occurs in the use process, it will cause great losses. If the temperature is too high, it is easy to cause the insulation core to soften and deform, and even lead to the insulation core wire sticking, resulting in unqualified products, so the preheating temperature must be strictly controlled. According to the above description, it is not difficult to see that the closing speed is also crucial, under a reasonable preheating temperature, if the closing speed is too fast, it will affect the melting of the hot melt adhesive, too slow will lead to the softening and deformation of the core wire, the consequences are the same as the improper preheating temperature, and the attenuation will suddenly increase at a certain frequency point.
For high quality Mini sas 5.0,MINI sas 6.0 and above wires, Jd-cables professional manufacturers are recommended。https://www.jd-cables.com
Post time: May-07-2024
