The quality control work of PCB circuit boards is mainly aimed at the effective management of the design, processing and inspection process of printed boards, as well as monitoring and measurement work.
1. Quality control in the design stage
The quality control work in the design stage mainly includes the following contents.
(1) The person in charge of the project should review the design documents of the printed circuit board and perform relevant approval procedures to ensure that the design documents are legal and effective. The printed circuit board made according to this document can meet the function and performance requirements of the equipment, otherwise it will be a waste of paper no matter how good the design is.
(2) Standardizers conduct normative review of the design of test points, structural forms, external dimensions, printed line layout, pads, cross-holes, characters, etc. of the printed circuit board to ensure the testability and specification of the printed circuit board It can meet the requirements of relevant national standards, national military standards and industry standards as much as possible.
(3) The project leader and the craftsman should check the process requirements for the production of the printed circuit board to ensure the manufacturability of the printed circuit board. If the process requirements are simple, they can be listed directly on the design drawings, and if the content is large, they can be written separately. Whether the process requirements are simple or complex, the processing process requirements should be accurately, clearly and coherently indicated. The audited process requirements should be able to meet the production process level at that time, be economical, cost-effective, and facilitate the development of subsequent assembly, debugging, inspection and other processes.
2. Quality control of PCB circuit board processing stage
The quality control work in the circuit board processing stage mainly includes the following contents.
(1) The quality department and the purchasing department conduct on-site inspection and certification of the qualifications and production capacity of PCB circuit board manufacturers to ensure that the PCB circuit board manufacturers have the ability to complete production tasks.
(2) The designer should re-examine the drawings used by the PCB manufacturer. Because the design of the printed board is often not a success, it needs to be revised several times. PCB circuit board manufacturers will have multiple versions of the processing drawings, so it is necessary to reconfirm the final processing drawings to ensure that the processed printed boards meet the requirements of the final version.
(3) Focus on the key processes in the production of printed circuit boards. Its quality has a great impact on the performance and reliability of the printed board, and quality control should be strengthened. Supervise and review the key process procedures formulated by the manufacturer, such as etching, hole metallization, etc., to ensure that the printed lines and pads are free of burrs, gaps, and bridge defects, and vias are free of nodules and voids. The "lamination" of multi-layer printed boards should also focus on quality control to ensure the thickness, bonding strength and positioning accuracy of the printed boards. High-frequency boards and microstrip boards usually require gold plating, and special gold-plating process work instructions should be formulated to ensure the thickness and purity of the coating.
3. Quality control in the inspection stage
The quality control work in the inspection stage is to monitor and measure the printed board strictly according to the inspection basis, through visual inspection or using special tooling and instruments, and keep records. If there are special requirements, special acceptance inspection rules should be formulated.