Heavy copper PCB manufacturer · Thick copper
Heavy Copper PCB: Thick Copper from 3 oz to 10 oz
Thick copper PCB constructions for high-current power distribution, from 3 oz to 10 oz per layer, including hybrid builds with heavy power layers and fine signal layers.
- Heavy copper per layer
- 3–10 oz
- Copper range
- 0.5–10 oz
- Current capacity
- 50–200 A+
- Heavy + 1–2 oz signal
- Hybrid
What is a heavy copper PCB
Thick copper PCBs, explained.
A heavy copper PCB (thick copper PCB) uses 3 oz (105 µm) or more copper per layer, versus 1–2 oz on standard boards. It carries high currents, spreads heat and survives thermal cycling in power electronics, often replacing bus bars and wiring.
Each ounce adds about 35 µm, so a 10 oz layer is 350 µm thick, almost as thick as a standard 2-layer board. Etching and laminating that copper takes specialized processes.
Copper weight conversion
Copper thickness: 1 oz copper thickness to mm, µm and mil.
| Copper weight | µm | mm | mil |
|---|---|---|---|
| 0.5 oz | 17.5 | 0.0175 | 0.7 |
| 1 oz | 35 | 0.035 | 1.4 |
| 2 oz | 70 | 0.070 | 2.8 |
| 3 oz | 105 | 0.105 | 4.1 |
| 4 oz | 140 | 0.140 | 5.5 |
| 6 oz | 210 | 0.210 | 8.3 |
| 10 oz | 350 | 0.350 | 13.8 |
One ounce of copper spread over one square foot is about 35 µm (0.035 mm, 1.4 mil) thick. Our copper range is 0.5 oz to 10 oz; heavy copper usually means 3 oz and above.
Why AstroPCB
Why choose AstroPCB as your heavy copper PCB manufacturer.
Heavy copper fails at etch and lamination: undercut traces, resin starvation between thick features and plating voids. As a heavy copper PCB manufacturer we plan etch compensation, prepreg fill and plating for your copper profile before release.
- 3 to 10 oz per layer on FR-4 and high-Tg FR-4
- Hybrid constructions: 3–10 oz power layers with 1–2 oz signal layers
- Engineering since 2008: 1,000+ engineers and 30+ partner factories in Shenzhen, Xi’an, Chengdu and Hangzhou
- Written DFM review on every order, prototype or production, before fabrication starts
- 99.6% on-time delivery across the partner factory network
- From 1 piece to volume with the same stack-up and process controls
- IPC Class 2 by default, Class 3 on request, with inspection records and batch traceability
- Fabrication plus assembly: component sourcing, SMT and tracked worldwide shipping
Specifications
Heavy copper specifications.
| Parameter | Capability |
|---|---|
| Copper weight | 3 oz (105 µm) to 10 oz (350 µm) per layer; 0.5–10 oz overall range |
| FR-4 heavy copper | Up to 10 oz |
| Hybrid | Heavy power layers + 1–2 oz signal layers in one board |
| Current | 50–200+ A depending on trace geometry and temperature rise |
| Plated holes | Heavy-wall plating for high-current vias |
Design rules
Minimum trace and space by copper weight.
| Copper weight | Typical min. trace / space |
|---|---|
| 3 oz | 150 / 150 µm |
| 4 oz | 200 / 200 µm |
| 6 oz | 250 / 250 µm |
| 10 oz | 380 / 380 µm or wider |
Size traces with the trace width calculator and read the PCB copper thickness guide.
Construction
10 oz heavy-copper PCB construction.
We build FR-4 heavy-copper designs up to 10 oz per layer. Final rules depend on copper distribution, minimum spacing, thermal relief, plated features, finished thickness and current. Each ounce adds about 35 µm, so a 10 oz layer is 350 µm thick and the finished board grows accordingly. We calculate stack-up thickness at quote.
- Provide current paths, power dissipation and ambient temperature
- Identify copper weight per layer and high-current interfaces
- Expect DFM review of etch compensation, clearance, drilling and assembly
Fabrication
Fabricating heavy copper.
Thick copper needs longer, controlled etching with compensation for undercut, because sidewalls taper as copper thickens. Lamination needs enough prepreg resin to fill between tall copper features without voids, and plated holes need heavier wall plating to carry current. Assembly needs more heat: large copper areas act as heat sinks during reflow and hand soldering, so thermal reliefs and profiles are planned accordingly.
RFQ
What to include in a heavy-copper RFQ.
- Copper weight per layer
- Maximum currents and allowed temperature rise
- Minimum trace/space by layer
- Finished thickness limit
- Assembly method and thermal-relief preference
Applications
Where heavy copper is used.
FAQ
Common questions.
What is a heavy copper PCB?
A PCB with 3 oz (105 µm) or more copper per layer, used for high current and heat spreading.
Thick copper PCB vs heavy copper PCB?
They are the same thing; both terms describe 3 oz+ copper constructions.
What is the maximum copper weight?
Up to 10 oz per layer. Our copper range is 0.5 oz to 10 oz.
When do I need heavy copper?
When traces carry more than about 10–15 A or the board must spread significant heat.
Can heavy copper be combined with fine-pitch signals?
Yes, with hybrid builds that put heavy copper on power layers and 1–2 oz on signal layers.
How does heavy copper affect board thickness?
Each ounce adds about 35 µm per layer; a 10 oz layer is about 350 µm, so finished thickness increases noticeably.
What is 1 oz copper thickness to mm?
1 oz copper thickness to mm is about 0.035 mm (35 µm, 1.4 mil) of base foil.
Ready when your files are
Send your design for a capability check.
Upload Gerber, ODB++ or IPC-2581 data. Every quote includes a written engineering DFM review, typically within one business day.