During the design phase of a product, it is necessary to control the development process to ensure that EMC's design concepts and methods are implemented accordingly at each stage. In addition, EMC design is considered from the perspective of the system of the product, not just a single part, which can ensure the final EMC performance of the product.
1.Overall product scheme design
In the overall scheme design stage, EMC design considerations are required for the overall specifications of the product, mainly involving the target market for product sales, as well as the standards and regulations that need to be met, while paying attention to the requirements of EMC standards and regulations in subsequent potential target markets. Propose an overall EMC design diagram for the product based on the requirements of the above EMC standards and regulations, and formulate a detailed overall EMC design plan for the product, such as how to design the shielding of the system, how to design the filtering based on the overall power topology of the system, and how to systematically consider the grounding of the product.
At this stage, the product R&D personnel propose an overall EMC plan, and the quality or specialized EMC engineers conduct a check based on the checklist.
2. Detailed product scheme design
In the detailed product design stage, it is mainly proposed to propose detailed EMC design and selection requirements for the overall hardware of the product, such as power interface, signal interface, cable selection, interface structure design, connector selection, etc. Ensure that these key points can be focused during subsequent implementation.
At this stage, product hardware designers propose detailed EMC solutions based on existing specifications, and quality or specialized EMC engineers conduct inspection based on the checklist.
3. Product schematic design
In the product schematic design stage, detailed solutions are proposed for the filter circuit design of the main chip inside the product, the filter circuit design of the crystal oscillator power supply pin, the filter circuit design of the clock drive chip, the filter circuit design of the power input socket, the filter circuit design of the external signal interface, as well as the selection of filter and protective components, the division of the functional and protective properties of the board, and the attribute definition of the screw hole on the board, EMC means to ensure filtering and grounding are implemented at this stage.
At this stage, the product hardware engineer performs detailed schematic design for EMC based on detailed program requirements and performs a check check based on the checklist.
4. Product PCB design
In the product PCB design stage, the main considerations are the design of stacked structures that have a significant impact on EMC, the layout of key components, and high-speed digital signal wiring.
The design of the laminated structure mainly considers the return flow of high-speed signals to the power plane;
During the layout stage, special consideration should be given to the placement of key chip components on the PCB, such as crystal oscillator positions, digital analog circuit settings, interface protection filter circuit placement, high-frequency filter capacitors, etc., the number and location of PCB grounding screws, connector grounding pin settings, and detailed segmentation of ground plane and power plane;
During the wiring phase, the emphasis will be placed on high-speed non-span division, routing protection for key sensitive signals, and reducing string winding.
At this stage, product PCB designers design PCB boards according to the company's relevant design specifications, and quality or specialized EMC engineers conduct inspection based on the checklist.
5. Product structure design scheme
In the product structure design stage, the design plan is mainly aimed at the product's need to meet EMC regulations and standards, including the shielding design scheme used for the product, the shielding material selected, and the thickness of the material. In addition, the overlap and gap design between the shielding bodies are considered, and the coordination between the interface connector and the structural member is also emphasized.
At this stage, product structure designers conduct product structure design according to the company's relevant design specifications, and quality or specialized EMC engineers conduct inspection based on the checklist.
6. Trial assembly of initial product sample
During the initial sample and trial assembly stage of the product, it is mainly to inspect the EMC design control measures for various aspects such as the overall design scheme, detailed design scheme, PCB layout design, and structural model in the early stage of product design, to see the implementation level of the proposed design scheme in the early stage; In addition, the main inspection is to check the coordination between the circuit board and the structure to see if there are any potential EMC hazards, so as to identify problems in advance, so that they can be improved together during subsequent product prototyping.
This stage is mainly for designers related to the complete product to jointly inspect and evaluate the product samples, identify processing issues and potential EMC hazards of the product, so as to facilitate the subsequent thorough testing and improvement of the version.
7. Product EMC Demonstration
After the trial assembly of the product is completed, if there are no special coordination issues, you can conduct EMC exploratory testing on the prototype according to the regulatory standards of the target market preset in the overall design plan to see if the product can meet the preset standard requirements. Whether the preliminary design scheme can meet the standard requirements needs to be verified at this stage. If there are any further problems, it is necessary to locate the existing problems, so that the product can be optimized and changed together during the next PCB modification and structural prototype.
This stage is mainly for EMC engineers to jointly conduct corresponding EMC mapping tests based on the product sales market. If there are minor issues, they can modify them. If there are no issues, they can decide whether to initiate certification based on the market development situation.
8. Product Certification
If the product can pass EMC testing according to the pre-designed scheme and method, then we can conduct product certification.
In short, EMC design synchronizes product design and does a good job at once!