The cost calculation of PCB assembly involves multiple factors, including but not limited to the following aspects:

　　Raw material cost: This is the main component of PCB assembly cost. Raw materials include substrate materials (such as FR-4), copper foil, solder mask ink, character ink, electroplating materials, etc. The price of each material will fluctuate based on factors such as market supply and demand, quality level, etc.

　　Manufacturing process cost: Different manufacturing processes can affect costs. For example, the manufacturing process of multi-layer boards is more complex and costly than single-layer boards; High precision and high-density wiring design will also increase manufacturing difficulty and cost.

　　Labor cost: Labor cost includes the salaries of workers directly involved in production and related management expenses. The labor cost may vary depending on the region, technological level, and labor efficiency.

　　Equipment depreciation and maintenance costs: The investment in equipment required for PCB manufacturing, such as drilling machines, exposure machines, etching machines, etc., is huge, and the depreciation and daily maintenance costs of the equipment are also part of the cost.

　　Testing and inspection costs: In order to ensure product quality, PCBs need to undergo strict testing and inspection during the production process. These processes require specialized testing equipment and human resources, which increases costs.

　　Logistics and warehousing costs: Raw material procurement, finished product transportation, and warehousing management all incur corresponding costs. These costs will vary with changes in transportation distance, storage conditions, and logistics efficiency.

　　R&D and design costs: For customized PCBs, R&D and design costs are also an important part that cannot be ignored. The design team needs to carry out circuit design, layout planning and other work according to customer needs, and this cost will be reflected in the final product price.

　　Management expenses and profits: Enterprise management expenses and expected profits will also be added to product costs. Management expenses include administrative office expenses, marketing expenses, etc., while profits are the return on investment for business operations.

　　In summary, the cost calculation of PCB assembly is a complex process that requires comprehensive consideration of multiple factors such as raw materials, manufacturing processes, labor, equipment, testing, logistics, research and development design, management costs, and profits. In order to accurately calculate costs, enterprises usually use professional cost accounting systems to record and analyze the costs of each link in detail.