In the manufacture of electronic products, multi-layer PCB (printed circuit board) design and production is an indispensable key link, patchwork design (Panelization) is a PCB manufacturing process commonly used in a technology, Topfast one-stop PCBA intellectual manufacturers today to talk about multi-layer PCB circuit board design rules?
Multi-layer PCB circuit board board design rules and techniques
- Importance of PCB design
PCB design is the layout of multiple individual PCB circuit boards on a large board, in order to process multiple PCBs at the same time in the production process, so as to improve production efficiency and reduce material and processing costs. Reasonable PCB design can improve productivity, reduce manufacturing costs, improve soldering quality, oand ptimize the subsequent process. - Basic rules for the design of patchwork
The size of the board should be designed according to the actual processing capacity of the production equipment. Common board sizes such as 250mmx250mm, 300mmx400mm, etc.. At the same time, the board should be reserved around the process edge, easy PCB in automated equipment for transmission, welding, and testing, usually 5mm ~ 10mm wide.
The type of board structure is divided into V-cut board, slot/bridge connection (Tab-Routing) board, and hybrid board, which is suitable for different working scenarios. According to the different ways of board splitting, the spacing between PCBs should be set reasonably to ensure that the PCB edges have sufficient margins, taking into account the use of the board after splitting, to avoid affecting the subsequent assembly. Use FiducialMark to help mounter and other equipment to identify the PCB position during the production process to ensure placement accuracy. - Multi-layer PCB design skills.
The layout of the puzzle board design, maximizes the use of material space, to achieve the effect of cost reduction and efficiency. At the same time, the heat distribution of different PCBs in welding is different, to ensure that the heat distribution of each PCB is uniform, such as the layout of the wise man, in the splicing board evenly distributed temperature-sensitive components to balance the heat, guarding the smoothness and harmony of the splicing board. In the face of complex shapes or shaped PCBs, designing a PCB is like facing a strange jigsaw puzzle, and special attention needs to be paid to its arrangement. In the design of the puzzle board, each PCB is reserved for the necessary testing points and interfaces to ensure that the test process can easily access the test equipment for the subsequent test process. Try to minimize the mechanical stress in the process of board assembly and depaneling, to ensure the quality of depaneling, and to ensure that the PCB after depaneling is as smooth as a mirror without traces.
At the same time, the multilayer board layer structure design is also very important, a reasonable layer structure can not only ensure the integrity of the signal but also improve the overall performance and reliability of the circuit board.PCB layer structure is mainly composed of Core and Prepreg (semi-solid sheet, referred to as PP). Core has two layers of copper foil, the filler between the layers of the solid material; and PP plays a role in the filler, the material is a semi-solid resin. PP is a semi-solid resin. Different thicknesses of Core and PP can be selected to form a variety of laminated structures to meet different design requirements. Before designing a laminated structure, the following prerequisites need to be clarified: the total number of layers on a single board, the thickness of the board, the target impedance, and the material of the PCB.
Laminated structure design flow, the goal of laminated structure design is to determine the arrangement order of signal, power, and ground layers, as well as the thickness of each layer and the parameters on the signal lines.
First: assess the number of signal layers required based on the layout design and the density of signal lines between key devices
Second: Determine the number of power and ground layers required based on the type of power supply and signal layer isolation requirements
Third: According to the target impedance and signal integrity requirements, select the appropriate PCB material
Fourth: Combined with the prerequisites, the design of the signal layer, power layer, ground layer arrangement order, and the thickness of each layer
Fifth: Utilize impedance calculation tools to calculate the line width and layer thickness of the signal line based on the target impedance and laminated structure parameters.
Multi-layer PCB PCB design needs to consider the process requirements, material utilization, thermal management, and subsequent processing steps. Through reasonable PCB design, as well as reasonable layer stacking structure design, to improve production efficiency,and reduce costs, while ensuring product quality, is to enhance product competitiveness and market responsiveness of the key.