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What is a 20 oz copper PCB?

A 20 oz copper PCB calls for nominal copper weight of 20 oz/ft虏 on specified conductive layers, approximately 700 碌m, 0.70 mm or 27.56 mil using the common rounded conversion. It is a substantial conductor thickness inside a PCB construction. It does not mean that every layer is 20 oz, that the complete board is 0.70 mm thick, or that the board has a fixed current capacity.

At this copper level, an early architecture discussion is valuable. A thick etched conductor may combine power distribution with the board's interconnection functions. A separate copper bar or strap may offer a different balance of geometry, assembly, insulation and serviceability. Compare the whole path and the interfaces before committing the product to either approach.

The catalog example above supports a product discussion; it does not approve a new combination of board size, spacing, layers and holes. Request a construction review with the actual layout. The heavy copper PCB family guide remains the broader entry point, while this page focuses on 20 oz architecture and project-specific fabrication decisions.

When thick etched copper is worth comparing with a separate conductor

Start with the reason for considering 20 oz. Is the available path too narrow, is voltage drop unacceptable, or does the design need to connect several power devices without additional hardware? State the required current waveform, route length, loss target and environmental boundary. A thickness chosen without these inputs can make fabrication harder without solving the dominant circuit problem.

An etched PCB route can reduce the number of separately mounted parts, but it also ties the power geometry to lamination, etching, mask and assembly constraints. A separate copper conductor introduces interfaces, support features and an assembly operation. Its metal section may be larger while its joints add enough resistance to erase the expected electrical advantage. Neither route is inherently superior.

Compare conductor and joint resistance explicitly

Enter the dimensions of a uniform PCB conductor and a separate uniform copper conductor. The PCB thickness field uses micrometres; the separate conductor thickness uses millimetres. Enter additional series connection resistance for each option in milliohms. These connection values should come from a defensible design allowance or measurement, not from the copper weight.

The example uses a 100 脳 10 脳 0.70 mm PCB conductor at 20掳C, giving about 0.2463 m惟. With 0.100 m惟 of entered connections, its total is 0.3463 m惟. The separate 140 脳 10 脳 2.0 mm copper path has about 0.1207 m惟 conductor resistance, but 0.400 m惟 of entered connections brings it to 0.5207 m惟. At 100 A the two example path losses are about 3.46 W and 5.21 W.

The thicker separate conductor has lower metal resistance but higher total loss under these particular joint assumptions. Change those assumptions and the comparison can change. The tool does not score suppliers, approve either design or estimate joint heating independently. It also excludes inductance, skin/proximity effects, contact aging and mechanical behaviour.

What changes when the copper is about 0.70 mm thick?

Think of the copper as part of the physical construction, not a small correction to a thin-board recipe. Etched gaps, conductor shape, laminate fill, copper distribution and mask coverage must be considered together. A narrow feature acceptable on a lighter board cannot be carried over without review. Minimum finished geometry should be agreed for the actual process rather than copied from a generic capability headline.

Thickness also consumes the board's mechanical envelope. Two nominal 20 oz layers alone sum to about 1.40 mm of copper before accounting for dielectric or surface allowances. That observation does not define a recommended finished board thickness, but it immediately exposes why a familiar board-thickness target may need reconsideration. Connector engagement, mounting and component lead length may all be affected.

Do not confuse 20 oz circuit copper with a copper-core PCB. A metal-core construction describes a thermal base and dielectric arrangement; it does not automatically provide the same electrical path as a thick patterned conductor. Use the copper-core PCB comparison when heat flow through a metal base is the actual selection task.

Review the narrowest transition and every interface

A broad power region often terminates at a smaller pad, hole, shunt or connector. Model that transition rather than reporting only the resistance of the main plane. For an interlayer route, hole-wall copper is specified separately from the surface conductor. The 10 oz interconnect workbench illustrates why a barrel group and additional joints belong in a series-path review.

For a bolted or soldered external conductor, define its interface geometry, finish, process and inspection requirements. Do not assume the connection has zero resistance or will retain its initial value under mechanical and thermal exposure. A resistance allowance is an assumption until supported by appropriate component data or representative measurement. Track that assumption in the design record and test plan.

Protect sensitive measurement paths from the high-current voltage gradients. The control circuit may need a defined sense point and separate routing strategy. Increasing the copper weight does not settle those connections, eliminate switching noise or guarantee a low-inductance loop. is useful background for treating parasitic resistance as one part of a broader circuit layout.

Request a process proposal before fixing every detail

Supply the intended copper map, complete pattern, target finished thickness and critical conductor dimensions. Include hole spans and wall requirements, insulation conditions, finish, quantity and assembly needs. Identify what is fixed by the product and what could change. An engineering proposal can then address a real design rather than a request for 鈥渕aximum copper with minimum everything else.鈥�

The manufacturing sequence depends on the approved construction. Starting foil, additional plating, etching, lamination and mechanical processing cannot be selected from a single universal recipe. A process proposal should identify the relevant dimensional and material requirements and the evidence needed to verify them. No animation or calculator on this page represents an approved production route.

Keep power and control functions separable in the discussion. A lighter comparison board may show useful interconnection ideas, but its geometry is not a 20 oz capability claim. If a mixed construction is proposed, verify the interfaces, thickness and acceptance requirements before updating the design files. The PCB DFM page provides a broader manufacturing-review framework.

Price the selected architecture, including its evidence

For 20 oz PCB procurement, copper mass alone is a poor price model. The proposal may be affected by geometry, panel use, material construction, tooling, lamination, holes, processing risk and the agreed verification scope. A separate copper path introduces different hardware, assembly and inspection costs. Compare complete quotations, not a bare-board price against an assembled alternative.

Use the budget brief to describe the proposed 20 oz construction and add supplier-specific unit, setup and validation allowances. The sample numbers are clearly labelled examples. No factory rate has been calibrated into this page. Leave all costs blank when requesting feasibility help; the technical brief remains useful before a price exists.

The generic per-board allowance should include only what your stated source includes. Separate conductor hardware, assembly, components, shipping and taxes need explicit treatment if they belong in the comparison. The PCB cost and manufacturability trade-off page can help evaluate a design change once the alternative costs and required validation are known.

What would demonstrate that the design works?

Define manufacturing acceptance and product validation as different deliverables. Appropriate dimensional and cross-section records can show that the agreed construction was made. Connectivity testing checks the electrical network within its method and settings. Neither establishes the product's behaviour at a specified load, ambient, airflow and mounting arrangement.

A representative validation plan should identify critical interfaces, load waveforms, operating conditions and acceptance criteria before the build. Use the applicable product requirements and selected . Copper thickness alone does not establish safety clearance, fault protection, material operating limits or reliability under cycling.

20 oz PCB questions