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PCB Options: Custom PCB Thickness

For PCB designers that require thinner or thicker PCBs then the standard 1.6mm, we here at MacroFab offer the ability to specify customized PCB thicknesses. The PCB specifications section of the platform allows you to specify the desired thickness of your PCB. The thickness can be specified from 0.2mm to 6.3mm in hundredths of a millimeter increments. Yes, we can make 2 layer PCBs as thin as 0.2mm! Some PCB Stack Ups and layer-counts will have higher minimal thicknesses due to additional material needed to manufacture the Stack Up.

The PCB Specifications section of the PCB Design Workspace. Here you can select different default PCB thicknesses or set a custom thickness!


The PCB Specifications section of the PCB
Design Workspace. Here you can select
different default PCB thicknesses or
set a custom thickness!

When you select custom thickness the PCB thickness field turns into a text field where you can enter the value you need in millimeters.


When you select custom thickness the PCB
thickness field turns into a text field
where you can enter the value you need
in millimeters.

 

The PCB thickness option appears on the PCB Specification tab of your PCB’s Design workspace, and provides a couple of standard thicknesses for quick selection, or the ability to input a custom thickness of your choosing. Selecting a custom thickness will prevent your design from being panelized with other designs, so minimum PCB area charges will apply, but no additional charges will be added unless you increase the thickness higher than that of the standard stackup for your layer count.

Creating Different Thickness PCBs at the Fab House

Given that we can adjust the thickness of the PCB in hundredths of a millimeter increment, it’s worth noting how the PCB fab actually accomplishes this. Let’s take a 2-layer board for example, with a standard 1.6mm thickness. Our expectation is that the PCB fab has some copper-clad core, with the total thickness of the copper and FR4 material equaling 1.6mm. Now, you probably wouldn’t expect that they’d also have that same core materials in 1.67, 1.68, and 1.69mm thicknesses — and you’d be right.

What are core and prepreg? Core material is an FR4 substrate that has been fully hardened and is pre-plated with copper foil. Prepreg (pre-impregnated) is a layer of epoxy resin that has not been fully cured, with a thin layer of fiberglass embedded in it. To make PCBs out of multiple layers, the prepreg is stacked and then pressed and heated. The epoxy cures fully during this process.

MacroFab's 2 Layer PCB Stack Up for 1.2mm overall thickness.

MacroFab’s 2 Layer PCB Stack Up for 1.2mm overall thickness.

To create a custom thicknesses, the PCB fab starts with a set of common core and pre preg thicknesses, then combines them in the necessary sequence, along with copper foil, solder mask, and copper plating thickness to reach the desired final thickness. For example, to make a 1.2mm thick 2-layer PCB, assuming our standard thicknesses of 0.035mm for 1oz of copper pour and 0.01mm for soldermask, you will need a single core layer at 1.07mm thick – demonstrated in the image to the right.

More information about PCB Stack Ups and the PCB specifications that surround them can be found in our knowledge base.