What problems should we pay attention to in the serpentine wiring of PCB?
In PCB wiring, serpentine wire is a special wiring method. Serpentine is a kind of routing method often used in Layout. Its main purpose is to adjust the delay and meet the requirements of system timing design; The two most critICal parameters are parallel coupling length (Lp) and coupling distance (S). So, what problems should we pay attention to in the serpentine wiring of PCB?
PCB circuit board serpentine wiring
1. The distance between parallel line segments shall be increased as much as possible, which shall be at least greater than 3H. H refers to the distance between signal routing and reference plane. Generally speaking, it is to route around a big bend. As long as the distance is large enough, the mutual coupling effect can be almost completely avoided.
2. Reduce coupling length. When the delay of twice the coupling length approaches or exceeds the signal rise time, the crosstalk generated will reach saturation.
3. The signal transmission delay caused by serpentine line of stripline or buried microstrip line is less than that of microstrip line.
4. For high-speed signal lines and signal lines with strict timing requirements, try not to use serpentine lines.
5. The serpentine routing at any angle can be used frequently, which can effectively reduce the coupling between them.
6. In the design of high-speed PCB, the serpentine line has no so-calLED filtering or anti-interference ability and can only reduce the signal quality, so it is only used for timing matching.
7. Carefully consider the following important issues:
(1) Are the minimum jumpers used? Do jumpers go through components and accessories?
(2) Is the letter visible after assembly? Is the size and model correct?
(3) Have large areas of copper foil been opened to prevent blistering?
(4) Is there a tool locating hole?
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