PCB Technical - ​What is the core concept of modern electronic assembly?

Modern electronic assembly should adhere to the core concept of "design is the source, material is guarantee, craftsmanship is the key, management is fundamental, and idea is the core", and discard the old thinking of craftsmanship and purely confined to craftsmanship. model.

Modern electronic assembly should adhere to the core concept of "design is the source, material is guarantee, craftsmanship is the key, management is fundamental, and idea is the core", and discard the old thinking of craftsmanship and purely confined to craftsmanship. model.

1. Design is the source

Ensure the correctness of the design, meet the requirements of DFM, DFA, DFR and DFT, and do not allow violations of the prohibition and restricted design and process regulations. Only by fully demonstrating and paying attention to the design's manufacturability, usability, detectability, manufacturing economy, and quality stability in the initial stage of design, can it be possible to achieve "zero defect design" and "zero defect" The dual purpose of "manufacturing" is that only such enterprises can provide the market with high-quality electronic products with high cost performance. China Electronics Technology has integrated the experience of domestic and foreign electronic assembly industry and group companies, as well as the latest requirements of relevant standards at home and abroad, and comprehensively develops and produces PCBA processes from four levels: manufacturability design, logistics, process optimization and quality control. Quality control requirements, covering typical assembly welding process types, new components, new materials, new technology applications and key process quality control requirements.

Combining design and process, and process and process control together, not only puts forward the quality requirements and quality objectives of PCBA, but also puts forward the design, material process optimization and quality control measures to achieve the above quality objectives in great detail. This is the first time that this approach has been praised as an internationally advanced level by well-known domestic electronics assembly experts in all previous standards and norms systems at home and abroad. The analysis of failure cases is very important, but it is also preliminary. General reliability analysts basically discuss cases based on cases, or focus on analyzing failure phenomena from a process perspective; and we just need to clarify what kind of failures are through case analysis. The design is wrong and there is no manufacturability. At the same time, the failure cases of high-reliability electronic products are mainly reflected in the phenomenon of violating the prohibited and restricted processes and designs. The emphasis is on what kind of design is absolutely prohibited. Through the above analysis, The managers of the enterprise, especially the first-in-command and the chief engineer of product models, have made it clear that the main cause of the quality problems of electronic products is the lack of manufacturability in the design. On this basis, the advanced design and management concepts of IPD and DFX are applied, with the goal of circuit design adapting to the advanced manufacturing technology of electronic assembly, and it is proposed to include design for manufacturability (DFM), electronic assembly process logistics quality control, and process optimization design., Staff requirements and comprehensive training and management system top planning five levels of system solutions.

Taking board-level circuits as an example, design for manufacturability is a parallel design that runs through the full life cycle of PCB/PCBA. It is completely different from the current lagging practice of most electronics companies' process work from the back end of the product development and production chain. It is also different from the manufacturability analysis in which the current popular technology is involved from the end of the design; it is carried out completely in parallel with the circuit design, that is, from the product tactical technical indicator demonstration and program design stage to the product after-sales service stage. .

2. Materials are guaranteed

Material is the most fundamental and basic component of the electronic assembly soldering process. It includes not only processing materials such as components and PCBs, but also process materials/auxiliary materials such as solder paste, solder, flux, patch glue, cleaning agent, etc., Its quality and whether it meets the requirements directly affect the quality of welding. Many quality problems of electronic assembly are often caused by defects in the physical and chemical properties of the materials used. Material quality control is the basis for ensuring the quality of electronic assembly.

3. Craft is the key

Optimize the process parameters, and do not allow violations of the forbidden and restricted process regulations to ensure that the quality of assembly and welding meets the requirements of high-reliability electronic equipment. The inherent design lack of manufacturability defects and material quality problems are difficult to compensate through improved process measures, that is to say, the process is by no means a panacea! Conversely speaking, good design quality and material quality will not naturally lead to reliable welding quality. We must focus on optimizing welding process parameters and establish a complete process quality control system for process research and development. Foreign developed industrial countries have always placed process technology research and experimentation in a prominent position. The proportion of funds and manpower invested in each research stage in the US industry is 1, if the basic theoretical research is 1, then the applied research is 5, the product development research is 20, and the process technology research is 300. In other words, the investment in process technology research is 15 times that of product development research! The situation in our country is quite the opposite. The "Global Effects of China's Innovation" by the well-known American think tank McKinsey Global Institute pointed out: "The reason why China has a large gap between scientific research innovation and developed countries is that the quality of the results of the scientific research innovation system is still out of proportion to the scale of investment. Although China’s R&D investment scale leads the world, only 5% of R&D funding is used to fund basic research, compared with 19% in the United States. Whether the emphasis on process technology research and testing directly affects the improvement of product quality and economic benefits increase.

4. Management is fundamental

Efforts should be made to enhance the sense of recognition of the necessity and importance of the implementation of DFX in the R&D and production process of electronic products by the leaders of all enterprises, and strive to make leaders at all levels fully realize that a company must be bigger and stronger, and the implementation of DFX is the only way! Without a centralized and unified process research department, without the support of powerful process personnel, the platform for implementing DFX will be lost.

5. Idea is the core

Circuit, structure, and technology are the three major technical elements that constitute electronic products. The three are indispensable and complement each other. An advanced and perfect electronic product must not only have a technologically advanced and economically reasonable circuit plan and structural design, but also The need for advanced process technology, the final realization of the product and whether it has market vitality, to a large extent depends on the advanced level of process technology. For electronic products, it is the process of designing the product's function, structure designing product form, and process designing product. Poor manufacturability design is the source that affects the quality of electronic products. This phenomenon is mainly manifested in the THT period and the early SMT period. In the THT period and the early days of SMT, an electronic assembly engineer only needs to understand the structural principle and composition of the equipment, according to the predetermined reliability expectations and goals of the design, and rely on the accumulation of experience to assemble it into an independent product. In this period, The reliability of electronic products mostly depends on the correctness of the design and manufacturability. With the rapid development of high-density and fine-pitch components, micro-miniature components and electronic assembly technology, the function of circuit design is gradually weakened. When the miniaturization of the product requires the application of high-density and high-precision QFP, BGA, CSP and other SMDs with lead center distance less than or equal to 0.3mm, as well as inch 0201, 1005 and metric 03015 chips, when the mounting density on the PCB board is higher than 35-50 pieces/ cm2, the solder joint density is higher than 100 dots/cm2, facing the 5th generation assembly technology represented by 3D assembly, multi-chip module (MCM) and 3D-MCM, it must rely on advanced electronic assembly technology and advanced electronic assembly equipment.