Factors to consider before designing and routing mobile phone PCB
Factors to consider before designing and routing mobile phone PCB
[Introduction] Setting wiring constraints 1. Report design parameters After the layout is basically determined, use the statistical functions of the PCB design tool to report basic parameters such as the number of networks, network density, and average pin density in order to determine the number of signal wiring layers required. The determination of the number of signal layers can refer to the following empirical data Note: The PIN density Setting wiring constraints 1. Report design parameters After the layout is basically determined, use the statistical functions of the PCB design tool to report basic parameters such as the number of networks, network density, and average pin density in order to determine the number of signal routing layers required. The determination of the number of signal layers can refer to the following empirical data. Note: The definition of PIN density is: board area (square inches) / (board pins / 14) The specific determination of the number of wiring layers must also consider the reliability requirements of the board. Signals work at speed, manufacturing costs and lead times. 2 Wiring layer setting l The PCB stacking arrangement needs to consider the following: Dielectric material (dielectric constant) The thickness of the entire PCB board and the number of metal layers The thickness of each metal layer The dielectric thickness between the metal layers is given to each metal layer The reference stack design of the electrical function distribution MTK is shown in Figure 1.2: MTK RF traces: Impedance control transmission lines are traces that connect RF signal sources and loads. Their nominal impedance is 50 ohms. In the mobile phone PCB, the 50Ω transmission line is implemented using the following two technologies: Microstrip line: The trace is routed on the outermost layer of the PCB, with the entire ground plane below it as the reference ground, and the periphery is surrounded by a large area of ground. Stripline: The traces are laid on the inner layer of the PCB. The adjacent upper and lower ground planes are their reference grounds, and the periphery is surrounded by a large area of ground. The reference design of the 50Ω trace is as follows: The line width is determined by the PCB's stack structure (some reference values are shown in the figure below). At least twice the safety clearance of the line width. There should be enough ground holes around the trace. Spreadtrum Impedance Control impedance control (eight layers) Spreadtrum commonly used mobile phone stacking method: the distribution method is not static, it can be appropriately modified according to functional requirements and required winding layer requirements. One thing to note is that the key routing layer must be close A complete reference level.
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