What is the PCB Fabrication Process?
The PCB fabrication process starts with designing the PCB. The process involves creating a schematic diagram of the circuit and converting it into a layout for the PCB. The design team must consider various factors, including the board’s size, the number of layers, and the materials to be used.
Engineers then use computer-aided design (CAD) software to develop a digital model of the PCB. The digital model is then translated into a Gerber file, a standard file format in the PCB fabrication industry that includes all the necessary details for manufacturing.
A prototype is created to test the design before PCB manufacturing. Prototyping involves producing a miniature version of the PCB to examine its functionality and potential problems. Photolithography is commonly used to create prototypes, involving transferring the digital model onto a copper-clad board.
During photolithography, a photosensitive substance is applied to the copper-clad board. The board is then exposed to ultraviolet light through a mask containing the digital model. The photosensitive substance is then developed, leaving behind a copper pattern that matches the digital model.
An acid solution is used to etch the copper pattern, leaving behind copper traces that make up the circuit. After etching, the board is cleaned and drilled to create holes for components.
After testing the prototype and making any necessary adjustments, the PCB is ready for manufacturing. The manufacturing process involves several steps:
- Material Preparation: The first step is to prepare the materials, including cutting the copper-clad boards to size and shape.
- Lamination: The boards are then laminated by layering the copper-clad boards with insulating material to form a sandwich-like structure, with the number of layers varying with design.
- Drilling: The boards are drilled to create holes for component insertion.
- Electroless Copper Deposition: The boards are plated with a thin layer of copper using electroless copper deposition to ensure proper trace connections.
- Plating: The boards are then plated with a thicker layer of copper using an electroplating process, forming the traces and pads on the PCB.
- Etching: The excess copper is then etched away using an acid solution, leaving behind copper traces and pads.
- Solder Mask Application: A layer of solder mask is applied to the board to prevent solder from flowing onto the wrong parts of the board during assembly.
- Silkscreen Printing: Component labels and other information are printed onto the board using silkscreen printing.
The PCB fabrication process is a complex and intricate process that involves various steps, from design and prototyping to manufacturing. Each step in the process is critical to ensure that the final product meets the design specifications and functions correctly. PCBs are essential components used in a wide range of applications.