Consider design factors during the PCB design phase. While manufacturing factors are equally important, these factors focus primarily on the function and purpose of the board rather than the practical considerations required in the manufacturing process. Some of the most important design factors that affect PCB thickness include:
1. Size, weight and flexibility
Thinner boards are lighter and more flexible than thicker boards, but are more prone to fracture due to their brittleness. While flexible PCBs must be thin to achieve their flexibility, applications that do not require flexibility for structural integrity may benefit from a slightly thicker board. However, while thicker boards are stronger, they also carry more weight and take up more space within the device. Both features can be problematic for light applications or devices with limited space capacity. The final application of the PCB printed circuit board determines these factors, which must be some parameters that are first defined before starting the PCB design.
2. Thickness of copper
The thickness of copper plays a role in the overall thickness of the PCB. The thickness of the copper layer used usually depends on the current that needs to pass through the PCB. The standard copper thickness is approximately 1.4 to 2.8 mil (1 to 2 OZ), but this thickness can be adjusted according to the unique requirements of the board. Due to material requirements and processing challenges, the thicker the copper and the thicker the board, the more expensive the board.
3. Board board
The operation and longevity of a PCB printed circuit board depends on the choice of materials, but these choices also affect the thickness of the board. Typical circuit board fabrication includes substrates, laminates, solder masks, and screen printing. Of these, laminates and substrates are the most important materials to consider, as they provide the structure of the board and greatly affect the overall thickness. Depending on the desired dielectric constant, the substrate can consist of paper and epoxy, glass braid, or ceramic. Laminates, on the other hand, consist of thermosetting resins and layers of paper or cloth. There are many options for both laminate and substrate, which determine the thermal, mechanical and electrical properties of the board, but also the overall thickness of the board.
The number of PCB layers affects the thickness of the board. While 2-6 layer PCB thicknesses may be within standard thresholds for PCB thickness, 8 layers and above may not be. While manufacturers can use thinner PCB layers to achieve standard thicknesses, this becomes increasingly impractical as the number of layers increases. In fact, if your design requires more layers, allow for a larger PCB thickness. If the design does not require multiple layers but needs to meet certain thickness parameters, reducing the number of layers will be the best option.
4. Signal type
The PCB printed circuit board carries a variety of signal types, which can determine the material required for the circuit board, which affects the thickness of the circuit board. For example, a board carrying high-power signals requires thicker copper traces and wider traces, which means it is much thicker than a board that operates in a low-power environment. However, high-density boards with more complex signals typically use laser microvias, fine traces, and thin high-performance materials, so they are traditionally thinner than other types of boards.
5. Via Type
PCB vias are routed through the board rather than on its surface, which is important for creating more compact designs. Many different via types are available, including: Via, Microvia, Blind Via, Buried, In-Pad Via.
The type and density of vias used will affect the thickness the board needs to accommodate. For example, micro-vias can be used for thinner PCB printed wiring boards because they are smaller and used for high-density connections.
The thickness of the printed circuit board and the materials it is composed of affect the conductivity and resistance of the PCB, so different thicknesses are required in different environments. For example, thin or flexible boards may not be the best choice for harsh operating environments. Additionally, thicker copper traces are less thermally stable at high currents, making them unsuitable for thermally varying or high-current environments. Connectors and components on the PCB are also critical because they have certain material and performance requirements that may be related to board thickness.
Based on these factors, designers can reasonably assess whether standard or custom PCB thicknesses are ideal. However, the design phase does not end there - manufacturers must then engage in discussions about their capabilities and how their capabilities affect the final PCB design.
In addition to design factors, manufacturing capabilities also play an important role in the final PCB printed circuit board design. Including thickness. Some manufacturing factors to consider include:
6. Drilling equipment
While designers typically focus on drill hole size and spacing for performance goals, the drill hole fabrication process adds a layer of complexity. When drilling any type of hole, PCB printed circuit board manufacturers are limited by the thickness of the board and the diameter and depth capabilities of milling machines and lasers. This limitation is expressed by the aspect ratio, which is the ratio between the depth of the hole and the diameter of the hole.
For standard drilling, all manufacturers should be able to achieve a 7:1 aspect ratio. Some manufacturers can achieve larger aspect ratios, but this must be discussed with the manufacturer before finalizing the board design, and is usually more expensive. For thicker boards, this means that manufacturers are less likely to implement small diameter holes.
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