Automotive electronics is the third largest application field of PCB after computer and communication equipment. Automobiles have gradually evolved from the traditional sense of mechanical products to electromechanical integration, intelligence, information technology of high-tech products, The use of electronic technology in automobiles is already widespread. No matter the engine system, or chassis system, information system, control system, safety system, interior environment system and so on all use electronic technology.

  A variety of electronic and electrical products in the process of working together, each other inevitably produce various electromagnetic interference, If these disturbances are not restrained by the corresponding technical measures, they will often cause the instability of the product or system. Printed circuit board is the basic component of electronic and electrical equipment of various automobile power products, and its electromagnetic compatibility problem is particularly important in product design.

  PCB on automotive electronics are subject to the same electromagnetic interference as other PCB, Or even more directly related to the usability of the product.

  A reasonable circuit layout should be:

1. minimize the delay of key signals and high-speed signals to control the reflection of signals.  
2. Control the consistency of the delay of the signal group, otherwise the collected data may be misplaced. 
3. maintain the overall balance of the wiring density on the whole circuit board to control crosstalk, and the wiring density of high-speed signals should be as small as possible.

  For special components, requirements that:

1. The connection between high-frequency components should be as short as possible, so as to minimize electromagnetic interference between them.
2. The components vulnerable to interference should not be too close to each other.
3. Input and output elements should be separated as far as possible. 
4. Increase the distance between components with higher potential difference to reduce common-mode radiation. 
5. The decoupling capacitor should be close to the power pin of the chip. 

  For common components, requirements that:

1. Place the devices of each functional circuit unit according to the circuit progress, so that the signal flow direction is as consistent as possible;
2. Layout around the core components of each functional circuit to minimize and shorten the leads and connections between components; 
3.  For high-frequency working circuits, the components should be arranged in parallel as far as possible to facilitate wiring.