Standard PCB Thickness: Sizes, Tolerances and Stackup Choices

The sizes below are industry examples for rigid boards, not a MOZPCB stock list or guaranteed capability. Inch conversions are approximate. Availability, panel support and minimum feature rules depend on material and layer count.

A core is a cured dielectric with copper cladding. Prepreg bonds the layers and its pressed thickness depends on the selected glass/resin construction and copper distribution. Copper contributes to the total, including any additional outer-layer plating. Solder mask and local surface finishes also matter when the mechanical measurement touches those surfaces.

Define where the finished thickness is measured and which coatings are included. At a card edge, for example, the relevant mating area may not have the same coating stack as the rest of the board. A drawing that says only “1.6 mm FR-4” leaves both the construction and acceptance method incomplete. See the copper-weight guide for the separate copper specification.

A nominal size is not a tolerance. As an arithmetic example, 1.60 mm ±0.16 mm permits 1.44–1.76 mm; that may be too wide for a particular socket or enclosure. This example is not a standard acceptance limit. Use the component or mechanical drawing to determine the allowable range, then ask whether the proposed stackup can meet it.

For a tight fit, identify the measurement location, sample plan and any local features such as gold fingers or countersinks. Discuss material availability and cost before releasing a tolerance copied from an unrelated design.

Impedance is strongly influenced by the dielectric distance between a trace and its reference plane, not just total board thickness. Two 1.6 mm multilayer boards can need different trace widths if their internal layer spacing differs. Use a proposed controlled-impedance stackup before final routing.

Thicker boards can increase the depth-to-diameter ratio of through-holes, complicating drilling and plating. Thin boards need handling, assembly support and panelization review. Adding layers does not dictate one finished thickness: material choices, dielectric spacing and copper must be balanced as a system.

Send the layer count, desired finished thickness and tolerance, material family, copper weight per layer, connector part number or fit drawing, hole requirements and any impedance groups. Identify whether the dimension is mandatory or whether an alternate is acceptable after approval.

For example, “six-layer rigid PCB; finished thickness 1.60 mm; mating-area range per attached connector drawing; propose stackup and confirm measurement method before tooling” communicates more than “standard six-layer board.” Add the exact acceptance range from your design rather than relying on the example. For flexible regions, use the flex construction and bend-radius guide instead of rigid-board thickness rules.