Manufacturing method of asymmetric impedance product
A production method and asymmetric technology, applied in the directions of printed circuit components and conductive pattern formation, etc., can solve the problems of terminal impedance mismatch, terminal scrap, signal distortion, etc., and achieve the effect of solving terminal impedance mismatch.
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Embodiment 1
[0031] like figure 1 As shown, it is a schematic diagram of the design of the conventional impedance line 2 and the reference layer 1 . It can be seen from the figure that the grid copper-clad areas on both sides of the impedance line 2 are in an asymmetric state, and the impedance line 2 is prone to impedance mismatch at this time. By performing impedance test on impedance line 2 in the design diagram, we can obtain the following figure 2 waveform shown. from figure 2 It can be seen that its impedance value range completely exceeds the industry's + / -10ohm variation range standard, and its maximum range is about 40ohm, which cannot meet the impedance matching requirements of the terminal device and can only be scrapped.
[0032] like image 3 A partial asymmetric scheme of the impedance line reference layer 1 of the present embodiment is shown. If the impedance line 2 is asymmetrical with respect to the reference layer 1, several areas with different residual copper rat...
Embodiment 2
[0037] In the flexible printed circuit board, the covering layer that has a great influence on the impedance value is generally electromagnetic shielding film, steel sheet, covering film polyimide film, and solder resist ink. When other conditions of the printed circuit board are constant, the influence of electromagnetic shielding, steel sheet, polyimide film covering film, and solder resist ink on the impedance value of impedance line 2 decreases in turn, and the width of the impedance line is proportional to its impedance value. inversely proportional.
[0038] Based on the above-mentioned known laws, the front of the impedance line 2 is covered with a covering film as a benchmark. If the impedance line 2 is asymmetrical with respect to the covering layer, the impedance line 2 is subjected to line width segmentation processing according to the material covered on the front of the impedance line 2 .
[0039]Specifically, if the front surface of the impedance line 2 is cover...
Embodiment 3
[0042] If the impedance line 2 is asymmetric with respect to the cover layer and the reference layer 1, the line width of the impedance line 2 is divided according to the residual copper rate in the reference layer 1 and the material covered on the front side, and the line width of the impedance line 2 is processed in turn. .
[0043] Preferably, if the front surface of the impedance line 2 is only covered with a cover film or solder resist ink, the line width of the impedance line 2 is processed according to the residual copper ratio in the reference layer 1. The line width of the impedance line 2 is processed.
[0044] The design of the line width of the impedance line 2 will be described below based on the first embodiment and the second embodiment, for different combinations of the reference layer 1 and the cover layer.
[0045] It is assumed that the impedance line 2 in the flexible printed circuit board is asymmetric with respect to the cover layer and the reference laye...
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