The Ultimate Guide: Factors Affecting PCB Thickness

We first need to understand what PCB thickness is . PCB thickness is the thickness of the finished circuit board. the nominal thickness of copper-clad boards is 0.5, 0.7, 0.8, 1.0, 1.2, 1.5, 1.6, 2.0, 2.4, 3.2, 6.4 mm. the nominal thickness of paper-based copper-clad boards is 0.7 to 1.5 mm

Standard Copper Thickness

When we talk about the thickness of copper when implementing a printed circuit, we are referring to the thickness of the tracks and pads, whether they are inside or outside of the layer.

PCB copper thicknesses are generally classified as 1oz (35µm), 2oz (70µm), and 3oz (105µm). Of course, the copper thickness depends on what kind of board you make. The greater the weight of copper, the better the electrical properties of the board. But the more difficult it becomes to etch the board. For mass production of boards, please make sure that the minimum pattern width/pattern pitch meets the specifications. We offer a complete customization service for you, please contact us to learn more.

PCB Core Thickness

The substrate, also known as the dielectric, is the insulating material that separates the two conductor layers. The core is a copper-clad material that hardly changes its thickness during the manufacturing process of the board.

In a two-layer printed circuit, there is therefore a central substrate between the two copper layers, often referred to as the top and bottom.

The standard thickness of the substrate is 1.6 mm for two-layer circuits and 4/6-layer multilayer circuits. However, due to the minimum thickness of the layers, usually the more layers, the thicker the printed circuit board.

Thicker or smaller thicknesses may be required for mechanical reasons or for characteristic impedance.

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Prepreg thickness

In the laminate structure of a printed circuit board, there are always 2 to 3 pieces of prepreg between the 2 copper cores. They are pressed together with the core.

Unlike the cores, the prepreg changes its effective thickness during the pressing process. Therefore, the thickness depends on the PCB manufacturer, its process setup and the ratio of copper cladding area to open space. 

Inner PCB thickness

In addition to the layer order, the true customization of the stack includes the definition of the internal PCB thickness. In particular, the vertical distance between the floor where the copper rails are placed.

It is important to clarify immediately that the internal thickness values do not have complete freedom. Because in fact, these thicknesses are the result of a specific construction order of the printed circuit. In a sense, to obtain a certain thickness configuration, it is necessary to build with a certain structure.

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Standard PCB thicknesses

Printed circuit boards have standards such as JIS, JPCA, IPC/JPCA, UL, etc. Materials and PCB thickness vary by standard. PCB thickness is not only the thickness of the board itself, but also the thickness of the copper foil section, the thickness of the plating section, etc., which varies depending on the material of the printed circuit board. 

The standard thickness of 2-layer PCB thickness is 1.6mm. our expectation is that the PCB fab has some copper clad core and the total thickness of copper and FR4 material is equal to 1.6mm.

If you want to control the copper thickness of the PCB, you just write your requirements clearly, tell us, and the manufacturer will make the copper thickness according to your requirements.

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