Printed Circuit Boards, abbreviated as PCBs, are one of the most indispensable platforms in contemporary electronics. These are mainly used for convection and connection of circuits and components. The thickness of PCB directly impacts its performance and the reliability factor associated with it. Usually, the standard PCB thickness comes in 0. 4-0.6 inches (1. 6 mm) thick, which, together with other properties, provides the necessary strength and adequate electrical characteristics. Although, it may vary according to the manufacturers.                       

Investing in electronics manufacturing companies is deemed feasible, especially given the fact that the current PCB market stands to be $80.33 billion in 2024. Thus, understanding circuit board thickness is important to compete effectively in the market.

This guide will offer a brief explanation of the PCB thickness and the way of measuring the PCB layer thickness. It will also explain the way of selecting thickness depending on the type of application. At the end of this course, you will be equipped with this cocktail of knowledge to guide you in producing designs that conform to standard industrial designs.

What is Standard PCB Thickness?

Standard PCB thickness usually describes the thickness that is most widely used in production, which is defined at 0.062 inches (1.6mm). The 1.6 mm thickness is thick enough for mechanical strength and electrical performance.

Several factors influence the choice of standard PCB thickness:

· Mechanical Strength: Bear component and remain to mechanical stress.

· Thermal Management: Enhances heat dissipation or reduces heat generated within or by the car.

· Cost Efficiency: Minimizes expensive processes in manufacturing, hence leading to the reduction of cost.

In total, the standard PCB thickness is 0.062 inches, which applies to different design and manufacturing requirements.

Types of PCB Thickness

It is to be noted that PCB thickness may differ from case to case depending on the characteristics of the appellation. Here's a list of common PCB board thicknesses used in the industry:

0. 031 inches (0. 8 mm)

Mainly found in small portable devices as they use up less space.

0. 047 inches (1. 2 Millimeter)

Offers a medium level of hardness/tackiness, which is ideal for many different uses.

0. 062 inches (1. 6 millimeters)

The most used thickness mentioned earlier is commonly used due to its strength and economy.

0. 091 inches (2. 3 mm)

Applied in industries where higher mechanical strength and thermal conductivity are needed.

0. 125 inches (3. 2 millimeters)

It offers greater tensile strength and is commonly applied in products containing bulky elements or high mechanical loads.

These thicknesses make it possible for those involved in the design to easily select the required PCB board thickness. The choice depends upon the mechanical, electrical, and thermal aspects of the particular project that they intend to undertake.

Constitutions of PCB Layer Thickness

You can find 2-layer PCB thickness, 4-layer PCB thickness, or other multilayer PCB thicknesses that vary depending on the design requirements. Understanding the PCB layer thickness involves examining the components that contribute to the overall thickness of a printed circuit board:

Substrate: Composes a foundation and offers mechanical support; it might be a formed dielectric material like FR-4 with the thickness varying between 0. 8 mm to 3. 2 mm.

PCB Copper Thickness: On the electrical interconnect, the most standard 1oz copper thickness stands at approximately 35 µµm. The higher-density current applications may call for 2oz copper layers or 3oz copper layers.

Prepreg Layers: These bond layers of the PCB, that lay down the insulation and thickness of the board, may vary according to the sizes and types of board.

Copper Foil Layers: In multilayer PCBs, incorporating extra copper layers will impact electrical and thermal characteristics.

Solder Mask and Silkscreen Layers: Copper traces should be protected and components should be labeled. However, they are very thin, they do contribute to the thickness of the printed circuit board.

Overlay and Other Coatings: Other thinner layers may then be deposited as per requirement for other protective purposes.

All these collectively describe the PCB layer thickness concerning the number of layers and design issues.

How to Measure the Thickness of PCB

Measurement of the thickness of PCB is crucial to meeting the intended design, besides fitting well within a specific application. Here are the primary methods used to measure the thickness of PCB:

Calipers

Often applied for the measurement of thickness of PCB, digital calipers can provide accurate readings of thickness for both single and multilayer PCBs. All that is needed is to position the jaws of the caliper across the PCB and find the measurement on the digital screen

Micrometer

As opposed to the calipers, which give merely estimates, micrometers are more suitable for high-precision measurement of the thickness of PCB. Put the PCB between the touching scales of the micrometer and note the value on the dial.

PCB Thickness Gauges

These are normally used in PCB measurements where they can give a precise thickness of PCB. It is perfect for use when conducting quality checks on products being manufactured.

Optical Microscopes

For improved accuracy, especially on multilayer PCBs, optical microscopes with measurement devices are employed. It also gives the correct readings of the thickness of the PCB.

Ultrasonic Thickness Gauges

Another method of measuring the thickness of PCB is ultrasonic thickness gauges, which employ sound waves. In panel industries, this technique is highly applicable when thick boards are used.

Selecting the most appropriate technique for gauging the thickness of PCB ensures that the PCB is of the correct thickness required and serves the intended function properly.

How to Choose the Right PCB Thickness Under the Influence of Multiple Factors

Choosing the right PCB thickness entails considering various factors that affect both the functionality and production process of the printed circuit board. Here's a guide to choosing the right PCB thickness based on multiple influencing factors:

Manufacturing Constraints

Thickness: Manufacturers usually provide a choice of PCB thicknesses: for example, 0.031 inches, 0.047 inches, and 0.062 inches. The selection of these popular thicknesses can decrease production costs further and make work easier.

Cost Implications: While using non-standard or thicker boards, the cost of production increases. When considering costs, choose conventional thicknesses in the industry to avoid the extra expenses of cutting.

Design Requirements

Mechanical Strength: In cases where rigid mechanical support is needed for the application because of heavy loads or excessive use, one should go for thicker substrates like 0.125 inches.

Thermal Management: High power, on the other hand, requires proper heat control and, thus, effective heat sinking. Thicker PCBs or increased copper thickness (e.g., 2oz or 3oz) can improve thermal circuit performance to meet thermal requirements when the circuit is subjected to thermal stress.

Electrical Performance: PCB thickness has direct implications on the levels of impedance and signal integrity. In high-frequency circuits, it is important to keep tight control of the thickness of the PCB substrate to maintain minimal loss of signal.

Regulatory and Compliance Standards

Industry Regulations: Some cases may demand strict compliance with the standards of certain industries, and the thickness of the PCB may be affected by this condition. Ensure that the specified thickness meets the requirements of codes governing the use of the material in the intended application.

By assessing these aspects, you can choose the most suitable PCB thickness where the design demands, manufacturability, and cost constraints are adequately addressed. These should be addressed as per the board design standards and reliability standards.

Conclusion

Picking out the best kind of PCB thickness is one of the most critical factors that must be taken into account in printed circuit boards. Some of the things to look at include manufacturing limitations, design specifications, intended application, and regulatory standards.

Selecting 'normal' thicknesses, such as 0.062 inches or thinner boards, can make manufacturing more accessible and less costly. The thicker ones might be preferable for strength and to 'shed' heat. Some measurement instruments, including calipers and micrometers, are used in mini wide-randomizing errors in the manufacturing process.

Considering these factors and following standards helps in selecting the right PCB thickness. This ensures both functionality and reliability in electronic designs. Or you can choose to come to PCBasic to buy the finished PCB assembly.

FAQs

1. What is PCB tolerance?

PCB tolerance refers to the allowable deviations in dimensions, including thickness, that ensure the board can still function and perform its tasks as designed.

2. What should one consider when determining the right thickness of copper to be applied on the PCB?

Select the copper finish of the PCB based on its existing use and the amount of heat that will enable its dissipation. Normally, it ranges from 1 oz per square foot of space, while the high-power uses may require you to include additional layers like 2oz.

3. What is the mean thickness of the copper layer in a printed circuit board or PCB?

Foils are available in varying thicknesses, and the most popular foil is one that is 1oz per square feet, 35 micrometers, or 1. 4 mil.

4. What kind of relationship does the thickness of the printed circuit board have with signal integrity?

As this paper seeks to show, the thickness of PCB plays a part in impedance and signal transmission. On the same note, the design also ensures that thinning does not in any way result in a compromise of the quality of the signal.