2. Technical Field
The invention relates to a method for manufacturing multilayer circuit boards and the multilayer circuit boards obtained by this method. In particular, as consumer electronic products increasingly develop towards being thinner, smaller, and smarter, the requirements for circuit boards (FPC) as important components are becoming higher. In existing technologies, the manufacturing of multilayer circuit boards typically involves using double-sided copper-clad substrates to create through holes or blind holes, and then fabricating inner conductive circuits from the double-sided copper-clad substrates, with conductive holes used to interconnect the inner conductive circuits. However, this method increases the thickness of the final multilayer circuit board, and if copper plating is applied to the copper-clad substrate, it increases the risk of inner circuit disconnection, affecting the quality of the finished multilayer circuit board. The invention aims to provide a method for manufacturing multilayer circuit boards that can solve the above technical problems and the multilayer circuit boards produced by this method.
3. Invention Content/Main Theme
The invention provides a method for manufacturing multilayer circuit boards, aiming to solve the problems of increased thickness and the risk of circuit disconnection in the existing technology. The core of the method lies in utilizing via filling technology to achieve interlayer electrical connections, while optimizing the manufacturing steps and simplifying the process.
Main Technical Features and Important Concepts:
- Stacked Structure: The multilayer circuit board includes an inner layer of the multilayer circuit board and copper-clad substrates located on both sides of the inner layer. The copper-clad substrates achieve interlayer conduction through conductive holes or via filling.
- Via Filling Technology: The invention particularly emphasizes the use of “via filling” to achieve electrical connections. The diameter of the via filling is less than or equal to the diameter of the conductive circuit it penetrates. The via filling is only used to connect the conductive circuit it penetrates with the next layer of conductive circuit. This differs from the conventional methods that typically use “blind holes” or “through holes” with copper plating.
- Manufacturing Method Steps (taking a multilayer board with a first conductive circuit layer and a second conductive circuit layer as an example): Provide a first copper-clad substrate, which has a first copper foil layer and a second copper foil layer.
- The first copper foil layer is made into the first conductive circuit layer, and the second copper foil layer is made into the second conductive circuit layer.
- Provide a second copper-clad substrate, which has a third copper foil layer and a fourth copper foil layer.
- The second copper-clad substrate is pressed between the surface of the first conductive circuit layer and the surface of the second conductive circuit layer to form a multilayer board.
- From the external side of the multilayer board, a first blind hole is created that penetrates through the third copper foil layer and the third conductive circuit layer, stopping at the second conductive circuit layer, and this first blind hole is formed as a via filling, which is only used to connect the third conductive circuit layer with the second conductive circuit layer.
- The third copper foil layer and the fourth copper foil layer are made into the third conductive circuit layer and the fourth conductive circuit layer, forming the multilayer circuit board.
- Advantages: Simplifies the manufacturing process and steps of the multilayer circuit board.
- By eliminating the steps of copper plating the surface of through holes, blind holes, and copper-clad substrates, the final multilayer circuit board is thinner.
- By using via filling to connect the first conductive circuit layer with the second conductive circuit layer, it avoids short circuits between inner conductive circuits, improving the reliability of the multilayer circuit board.
- Via Filling Position and Function: Via filling can penetrate part or all layers of the multilayer circuit board, and its core function is to achieve electrical connections between specific conductive circuit layers. The diameter of the via filling is the key control factor.
4. Important References and Facts:
- Provides schematic diagrams of specific embodiments of the invention, demonstrating different stacked structures and applications of via filling, blind holes, and through holes. “In summary, when manufacturing the inner conductive circuit 110 of the multilayer circuit board 100 and the second conductive circuit layer 120, the inner conductive circuit layer 110 is not electrically connected to the second conductive circuit layer 120 through electroplating. All conductive holes of the inner conductive circuit layer 110 are formed simultaneously with the inner conductive holes used for conducting the multilayer circuit board 100, eliminating the steps of creating through holes or blind holes in the first copper-clad substrate before forming the inner conductive holes of the multilayer circuit board 100 and the outer conductive holes, and eliminating the steps of copper plating the surface of through holes, blind holes, and the first copper-clad substrate to conduct the inner conductive circuit layer, simplifying the manufacturing process of the multilayer circuit board and saving costs; by eliminating the copper plating of through holes, blind holes, and the surface of the first copper-clad substrate, the final multilayer circuit board is thinner, and by using via filling to connect the first conductive circuit layer with the second conductive circuit layer, it avoids short circuits between inner conductive circuits, enhancing the reliability of the multilayer circuit board.” This is an important summary of the main advantages and technical innovations of the invention.
5. Potential Impact/Importance
The invention provides a new approach to manufacturing multilayer circuit boards. By introducing via filling technology, it effectively addresses the issues of increased thickness and short circuit risks present in traditional manufacturing methods. This is of significant importance for consumer electronic products that pursue thinness and high performance, helping to improve the integration and reliability of circuit boards. Simplifying the manufacturing process also helps reduce production costs.
Summary:
The invention proposes a method for manufacturing multilayer circuit boards using “via filling” technology. By performing via filling at specific locations instead of traditional electroplating of blind holes or through holes, the manufacturing process is simplified, costs are reduced, and most importantly, the thickness of the finished circuit board is reduced, while improving the reliability of interlayer connections and avoiding short circuit issues in inner circuits. This technology has a positive impact on meeting the demands for thin, high-performance circuit boards in modern consumer electronic products.