How Thick Should a PCB be?

Before now, the performance or overall outputs of a Printed Circuit Board (PCB) is adjudged by factors like the prototype, the material used for the construction and the fabrication process. Recently, concentration has turned to the possible influence of the thickness on the board’s performance.

It is for this purpose that we made this post to help you understand the intricacies of thick PCB and how the thickness could be an influence on the board’s performance.

What is Thick PCB?

Essentially, this has to do with the extent of the circuit board’s thickness. The thicker it is, the higher the consideration as a thick PCB.

What Makes a PCB Thick?

If you are looking at some of thick properties of a PCB, some of the things to look at it are the type of material used for the board.

What is the Standard PCB Thickness?

Today, there are a wide range of thickness options for Printed Circuit Boards (PCBs). These options can further be niched down to the core standard. While there might be variations of PCB’s thickness, based on the type of material used and other factors, there is a standard that regulates it all.

One of the primary standards for circuit board thickness is the 1.57mm or the 0.062-inch standard thickness. It is possible for the PCB manufacturer to have a different interpretation for this, such as using 1.5mm instead of 1.57mm.

PCB Thickness Variations

In addition to the standard thickness option, there are a couple of other thickness options you can explore for your Printed Circuit Boards (PCBs). These options include but are not limited to:

  • 0.78mm or 0.031-inch
  • 2.36mm or 0.093-inch
  • 0.78mm or 0.031-inch
  • 2.0mm or 0.079-inch
  • 0.8mm or 0.032-inch

Essential Design Factors for Thick PCB

Do you know that the design iterations have a role to play in the overall thickness of a Printed Circuit Board (PCB)?

Here are some of the design factors that could potentially make all the difference:

1. Copper Weight

Copper is the most significant metal that aids the functionality and the application of the Printed Circuit Board (PCB). Therefore, it is imperative to be certain of the thickness, which is often accentuated by the weight.

Here are some of the things you need to know about how the thickness of the copper can make all the difference:

  • The copper’s thickness is directly proportional to the application it is to be used.
  • Although the standard copper thickness is between 1 oz and 2 oz (or between 1.4 and 2.8 mils), the thickness is subject to adjustment, especially if the required application has a higher copper thickness demand.
  • It is also possible to make further adjustments in the PCB thickness, especially as it has to do with the prepreg’s thickness adjustment. This way, it would be possible for the copper thickness to meet up with the targeted PCB thickness.

2. PCB Cost has Some Roles to Play

One may have wanted to focus only on the prepreg thickness and the overall thickness of the components used on the PCB.

However, the cost of getting the PCB manufactured is another potential factor influencing the thickness of the circuit board. These significant factors cut across the PCB yield, the number of layers used and the overall size of the circuit board.

Here is a breakdown of how some of those factors could influence how thick the PCB would be:

3. The Correlation of Flexibility with Size and Weight

The size, weight and flexibility of the PCB are integral factors that influence what the thickness would be like.

The calculation is that a thicker Printed Circuit Board (PCB) thrives better in certain scenarios, especially if it is used with applications that require bending. With this in place, there is an assurance that the board wouldn’t bend or be subject to cracks when folded in a particular direction for some time.

Another factor to consider here is the flexibility of the board. In some cases, it is better to go for the thinner PCBs, which are more flexible than the ones that have more thickness.

4. The Number of Layers

How many layers are packed into the Printed Circuit Board (PCB)? The simple calculation is that the more layers are added to the circuit board, the higher the possibility of the board being thicker.

Note that the standard number of layers to use in a circuit board is anywhere between 2 and 6 layers. While we understand that the targeted application’s requirements might need more layers than the specified, it is also pertinent to note that more layers equal more thickness.

5. The Type of PCB Material

This is evident – the thickness or composition of the material used on the PCB has a way of impacting the thickness.

The core material focal points are the silkscreen, substrate, solder mask and laminate. It is pertinent to mention that these focal points refer to the major places where the materials are needed. So, if you have a need to place materials in some other parts of the circuit board, you should be willing to make extra preparations for the increased thickness.

Besides impacting the board’s thickness, the materials (especially those used for the substrate and laminate) have additional contributions to the PCB’s thickness. These additions range from the impacts on the mechanical, thermal and electrical properties/compositions of the circuit board.

Manufacturing Iterations to Consider

The manufacturing factors also have a way of impacting the PCB’s thickness. In this case, we are looking at the possibility of having an increased thickness due to factors like depanelization.

The depanelization method, for instance, has to do with the paneling structure of the circuit board. For example, it is common for the less thick or thinner PCBs to be depanelized with breakaway tabs, while the thicker boards are depanelized with the V-scoring depanelization method.

6. Surface Finish

The processes involved in finishing the board’s surface could potentially leave some residues, and this, in turn, impacts the thickness.

7. Layer Count

When manufacturing a PCB, one important factor to consider is the number of layers it has. If the layer count is higher, you can expect the board’s thickness to increase likewise, because more layers often mean working on multilayered PCBs.

Final Words

Overall, a PCB’s thickness is impacted or influenced by factors like the type of materials used, the number of layers it has and the range of manufacturing factors. You can partner with Hillman Curtis to optimize your circuit board project with the thickness level you prefer.

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