09/08/2023
PCB fundamental concepts
How to understand the PCB? A printed circuit board (PCB) is an electronic assembly that uses copper conductors to create electrical connections between components. Printed circuit boards provide mechanical support for electronic components so that a device can be mounted in an enclosure. A printed circuit board design must include a specific set of steps that aligns with the manufacturing process, integrated circuit packaging, and the structure of the bare circuit board.
Conductive features on printed circuit boards include copper traces, pads, and conductive planes. The mechanical structure is made up of an insulating material laminated between layers of conductors. The overall structure is plated and covered with a non-conductive solder mask, and a silk screen material is printed on top of the solder mask to provide a legend for electronic components. After these fabrication steps are completed, the bare board is sent into printed circuit board assembly, where components are soldered to the board and the PCBA can be tested.
Types of PCBs
Today I only introduce 5 types common pcbs:
• Single-sided - This board only has components mounted on one surface. The back surface is typically fully copper (ground) and coated with a solder mask.
• Double-sided - This type of circuit board has components mounted on both surfaces. Each surface is defined as a signal layer in the PCB stack-up, so the surfaces will contain traces that carry signals between components.
• Multi-layer PCBs - These boards have conductors on internal layers that carry electrical signals between components, or the internal layers could be conductive plane layers. Multi-layer PCBs may be single-sided or double-sided.
• Rigid PCBs - These boards are fabricated and assembled on rigid laminate material, such as FR4-grade epoxy resin-impregnated fiberglass laminate materials. Other types of rigid laminate materials are available as well, which provide different material properties for use in some specialized applications.
• Rigid-flex PCBs - Rigid-flex PCBs use a flexible polyimide ribbon that connects two or more rigid sections in a printed circuit board assembly. A rigid-flex board might be used when the design must have some movable element, such as a folding or bending enclosure.
• Flex PCBs - Fully flexible PCBs do not use any rigid materials and are made entirely of flexible polyimide ribbons. These boards can have components mounted and soldered on the, just like rigid and rigid-flex printed circuit boards.
