Quick Answer
PCB thickness is the finished Z-dimension of a printed circuit board after the copper, dielectric cores, compressed prepregs and surface finishes are combined. A common nominal rigid-board thickness is 1.6 mm (about 63 mil), but the correct value depends on layer count, copper weight, dielectric build and mechanical requirements. Use the calculator below to estimate a finished stackup; for production, confirm pressed prepreg thickness and tolerance with your PCB fabricator.
Finished PCB Thickness Calculator
Use finished copper weight and compressed prepreg thickness where available. Values are engineering estimates, not a fabrication release. the material grades these numbers apply to carries the material data the model assumes; the selection guide explains how to choose between grades.
Important: prepreg thickness after pressing depends on glass style, resin content, copper pattern and lamination conditions. Finished outer copper may also differ from starting foil because of plating. Use your fabricator's approved stackup for production.
PCB Copper Weight → Thickness Converter
This secondary converter targets the common engineering question “how many mm is 1 oz copper?” It is not a full PCB weight calculator.
PCB Thickness Chart: Common Finished Board Targets
| Board / layer count | Common nominal targets | Typical reason |
|---|---|---|
| 2-layer rigid PCB | 0.8 / 1.0 / 1.6 mm | General electronics, compact assemblies |
| 4-layer PCB | 1.0 / 1.2 / 1.6 mm | Mainstream multilayer stackups |
| 6-layer PCB | 1.2 / 1.6 / 2.0 mm | More dielectric and plane layers |
| 8-layer PCB | 1.6 / 2.0 / 2.4 mm | Higher layer count, rigidity, impedance structure |
| 10–12 layer PCB | 2.0 / 2.4 / 2.8 mm | Dense high-layer-count designs |
| Backplane / heavy board | 2.4 / 3.2 mm and above | Mechanical stiffness and dense multilayer construction |
These are common nominal design targets, not universal standards or guaranteed fab capabilities. Layer count alone does not determine thickness.
Core Thickness, Prepreg and Copper: What Actually Builds PCB Thickness?
A rigid multilayer PCB is a laminated stack of copper foil, copper-clad cores and prepreg dielectric. The core provides a cured dielectric layer; prepreg is partially cured resin/glass that flows and bonds during lamination. Copper weight contributes additional thickness on every conductor layer, while solder mask adds a small surface contribution.
| Item | What it is | Thickness relevance |
|---|---|---|
| FR-4 core | Fully cured laminate, usually copper clad | Often the largest single dielectric contribution |
| Prepreg | Resin-impregnated glass used to bond cores/foils | Final pressed thickness varies with construction and resin flow |
| Outer copper | Finished conductor on top and bottom | Starting foil plus plating can affect finished thickness |
| Inner copper | Internal conductor layers | Approx. 35 µm per 1 oz/ft² layer |
| Solder mask | Protective polymer on outer surfaces | Small but relevant when modelling a finished board |
How to Measure PCB Thickness: Three Routes and What Each One Costs You
Thickness is one of the few numbers where the method decides the answer. A micrometer, a cross-section and an ultrasonic gauge will disagree on the same board, and all three can be right, because they are measuring different things. Pick the method from the question you are actually asking.
| Method | What it measures | Typical uncertainty | Use it when | What breaks the reading |
|---|---|---|---|---|
| Micrometer, contact | Total finished thickness at the point touched | Resolution 0.001 mm; practical repeatability around ±0.005–0.01 mm on a clean flat area | Incoming inspection, per-panel check, control chart on one panel position | Solder mask softness, burr at a hole, measurement over a via or a copper pour, tilted anvils |
| Cross-section (microsection) | The layer build itself — each core, prepreg and copper layer | Layer measurements typically to a few thousandths of a millimetre, depending on preparation and magnification | Verifying a stackup, investigating an impedance miss, qualifying a new fabricator | Polishing damage, non-perpendicular cut, measuring a smear as if it were copper |
| Ultrasonic or eddy-current gauge | Total thickness without contact | Typically around ±0.01–0.02 mm, and worse on multilayer with mixed dielectrics | Fast screening, thin or flexible panels, measuring over mask | Unknown sound velocity, air gap under the probe, copper distribution under the spot |
| Optical / confocal depth | Depth from one surface to a feature, rather than total thickness | Micrometre-level on a clean surface | Back-drill depth and cavity depth, not board thickness | Translucent mask, roughness, reflection from shiny copper |
For a finished-board check, a calibrated micrometer read at defined flat locations is still the working method, provided the sampling plan is written down. Define the measurement points by panel coordinate, not by “somewhere flat”, or two inspectors will produce two different control charts from the same lot.
Where thickness measurement goes wrong in practice
- Measuring at a hole. Drill burr, or a slightly proud annular ring, adds apparent thickness. Measure a solid area, and state that the reading excludes hole locations.
- Measuring a masked board as if it were bare laminate. Solder mask adds a few tens of micrometres. It matters when the tolerance is tight, and it is the usual reason bare-panel and finished-panel numbers do not match.
- Treating a thickness reading as a stackup verification. Total thickness can be right while one dielectric is thin and another is thick. Only a cross-section separates those.
- Using one panel to characterise a lot. Finished thickness moves with press conditions across the panel; a single reading near the edge underestimates the variation inside it.
Thickness, drill depth and the number that actually matters
Once a board is back-drilled, total thickness stops being the controlling number. Depth is referenced from one surface, and what the design cares about is the residual stub, which is not a thickness measurement at all. If that is your question, the arithmetic is in the back-drill depth and stub calculator, and the drawing conventions are in the back-drill design rules.
PCB Thickness vs Drilling Stack Height
The finished PCB thickness does not include the aluminum entry sheet or the HDF/melamine/phenolic backup board used during mechanical drilling. Those consumables increase the total drilling stack height and can affect tool exposure, aspect ratio and process setup, but they are removed after drilling.
For the full drilling stack, use the PCB Stack Height Calculator. For the effect of board thickness on hole geometry, use the PCB aspect ratio calculator.
PCB Thickness and Via Aspect Ratio
Aspect ratio is commonly expressed as board thickness ÷ finished or drilled hole diameter. A 1.6 mm board with a 0.20 mm hole has an 8:1 ratio. Higher ratios increase plating and drilling difficulty and should be reviewed with the fabricator, especially for HDI, high-layer-count and reliability-critical boards.
PCB Thickness Reference Map
When Board Thickness Matters in PCB Drilling
For YUESHAN's drilling-material users, finished board thickness becomes a process input rather than just a mechanical dimension. Thicker boards and larger stack heights increase drill engagement length and can raise the importance of stable entry material, backup support, tool condition and chip evacuation.
For total board thickness, work from the cross-section rather than the laminate call-out. Each copper foil contributes its finished thickness — 35 µm base copper is roughly 1 oz (the full form of oz in a stackup is ounce per square foot of foil weight), 40 µm outer-layer copper is a common spec, and it is the finished copper thickness after plating, not the foil weight, that adds to the build. Prepreg and core sheets contribute their pressed thickness, and the sum is what the drill and the backup stack actually see. A 2-layer 1.6 mm board with 1 oz copper, or a thicker 2 oz build on a 1.6 mm core, both resolve the same way: layer by layer, with the oz-to-µm conversion (1 oz ≈ 35 µm) done once instead of skipped.
FAQ
What is the standard thickness of a PCB?
1.6 mm (about 63 mil) is the most common nominal rigid-PCB thickness, but it is a convention rather than a universal requirement. Thin, heavy, high-layer-count and connector-driven boards use other targets.
How do I calculate total PCB thickness?
Add the finished thickness of all copper layers, cores, compressed prepregs and optional solder-mask layers. The calculator above separates each contribution so you can see what drives the final number.
How many mm is 1 oz copper?
Approximately 0.035 mm (35 µm). 0.5 oz is about 0.018 mm, 2 oz about 0.070 mm and 3 oz about 0.105 mm.
How do I measure PCB sheet thickness?
Use a calibrated micrometer or thickness gauge on clean, flat finished-board locations. For internal core/prepreg/copper thickness, use a cross-section or the approved fabrication stackup.
Does a 4-layer PCB have to be 1.6 mm?
No. 1.6 mm is common, but a 4-layer PCB can be thinner or thicker if the core/prepreg build, impedance, stiffness, connector and fabrication requirements support it.
Is board thickness the same thing as board weight?
No. Thickness describes the Z-dimension. Board mass additionally requires length, width, dielectric density, copper coverage and often component weight. “Copper weight” in oz/ft² is a separate conductor-thickness convention. For the board-mass side, work out board mass from size and density.
Bagaimana cara menghitung ketebalan PCB multi-lapis?
Jumlahkan tebal tembaga selesai pada setiap lapisan, inti (core) yang telah dipadatkan, prepreg setelah pengecekan, dan lapisan solder mask. Kalkulator di atas memisahkan setiap komponen agar terlihat mana yang paling memengaruhi hasil akhir.
Apakah ada kalkulator berat PCB?
Ada — kalkulator berat PCB kami menghitung massa panel dari panjang, lebar, tebal selesai, dan densitas material, lengkap dengan konversi g / oz / kg / lb untuk perencanaan pengiriman.
Technical References
- IPC — rigid printed-board performance standards: IPC-6012 covers qualification and performance requirements for rigid printed boards.
- Cadence — Standard PCB Thickness and Optimization: background on common nominal thicknesses and design trade-offs.
- Altium — PCB layer stackup considerations: layer count, dielectric structure and manufacturability context.
External references provide standards and design context only. Fabrication tolerances and pressed material thicknesses should be confirmed with the board manufacturer.