Key Design Factors Influencing PCB Thickness for Reliable Performance

Feb 12,2021

Thickness is a crucial factor in PCB design and manufacturing. The standard PCBs are designed and developed on standardized values of thickness. However, the customized PCBs are designed for various thicknesses, weights, and the number of layers, therefore, in customized PCB manufacturing thickness plays a crucial role. Although thickness itself is a design parameter for PCBs, it is not totally independent. The PCB thickness is connected to several other design parameters like the number of layers, weight, and many more. This post discusses the standard and custom PCB thickness, followed by the list of factors that impact selecting or achieving the thickness.

An Overview and Types of PCB Thickness

PCB thickness is basically the collective thickness of the PCB core, solder-mask, the substrate layer, the thickness of the copper layer (multiplied by the number of layers), and so on. Since the overall thickness of PCBs is a collective entity, it differs according to different factors like thickness and number of copper layers.

However, there are two types of PCB thickness are adopted in the PCB design and manufacturing process, listed as follows.

• Standard Thickness:

  Several contract PCB manufacturers adopt nearly 0.062 inches (1.57) mm as the standard thickness for standard PCBs. However, as the demand for compact PCBs is increasing, small-sized and mid-sized PCBs are also gaining popularity. Today, the PCBs are available in three standard thickness values as 0.031inches (0.78mm), 0.062inches (1.57mm), and 0.093inches (2.36mm). To achieve a standard thickness, the thicknesses of layers and other elements are adjusted in this type.

• Custom Thickness:

  The custom thickness of PCB is versatile. As the name suggests, it can be customized based on the design requirements. In order to accomplish custom thickness, the adjustment in thicknesses of different elements can be made or overall thickness can be adjusted based on different elements. Now let us discuss different design factors that may impact the selection of PCB thickness.

Design Parameters that Impact on PCB Thickness (Standard/Custom)

The below-listed parameters directly or indirectly impact the thickness of PCBs.   

• Weight:

  Higher the thickness, the bulkier the PCB becomes. In order to maintain a specific weight of PCB assembly, the thickness has to be maintained.

• Flexibility:

  In the case of flexible PCB or rigid-flex PCB designs, flexibility is important. In order to bring structural integrity for flexible or rigid-flex PCBs, the thickness should be lesser. The thinner the PCB is, the greater is the flexibility. Therefore, based on flexibility requirements, the thickness has to be decided.

• Copper Core Thickness:

  The copper core thickness is one of the elements of the overall thickness of the PCB. Thus, it must be chosen wisely to match the desired thickness.

• Board Material:

  The board material is chosen according to the desired thermal, mechanical, and electric properties of the PCBs. The complete fabrication of a PCB may include different substrate materials, silkscreens, solder pastes, epoxy resins, etc. The material properties and thickness must be compatible with each other in order to customize the PCB properties.

• Number of PCB Layers:

  As the number of layers increases, the overall thickness of PCB eventually increases. Therefore, the thickness should be decided based on the number of layers.

• Types of Vias:

  The PCBs in modern electronics require high-density fabrication, therefore, different types of vias are adopted. In these types of vias, the through-drill assembly of the PCB components is done. The board thickness must be able to accommodate vias and fabrication.

• Types of Signal Traces:

  Due to electric signal transmission, the PCBs may be exposed to various temperatures and frequencies. The thickness must be capable to handle certain stresses caused due to temperature and electric frequencies.

• Operational Conditions:

  The operating situations must be checked before selecting the board thickness. A very thin PCB may not sustain a rugged operational environment, whereas a thick PCB may offer enough flexibility for modern-electronic operations.

The OEM must consider all these factors to select the appropriate board thickness. Most experienced contract manufacturers would help them understand the impact of each of the above factors and often help them to design PCBs based on their requirements. Creative Hi-Tech is one such reliable and experienced manufacturer, which offers PCB fabrication services to industries like medical, electronics, aerospace, and many more. They can offer high-quality standard or customized PCB manufacturing services based on your operational requirements.

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