Brass vs. Copper for CNC-Machined Electrical Connectors: Conductivity, Machinability and Plating

Choosing between brass and copper for a machined electrical connector is rarely as simple as asking which material conducts electricity better.

When comparing brass vs. copper for electrical connectors, the right choice depends on what the part actually does.

A high-current terminal may need maximum bulk conductivity. A threaded connector body may benefit more from reliable threads and efficient machining. A small precision contact may require both electrical performance and complex CNC features.

The real decision is therefore a balance between conductivity, machinability, geometry, plating and production volume.

Brass or Copper for an Electrical Connector: What Is the Short Answer?

A practical starting point is:

• Choose C110 copper when maximum electrical conductivity drives the design.
• Review C145 tellurium copper when the part needs high conductivity plus better CNC machinability.
• Consider C360 brass when complex threads, turned features and production efficiency matter more than maximum conductivity.

The key is to select the material around the electrical function of the component.

A current-carrying contact, a threaded connector body and a small precision pin do not necessarily need the same alloy.

When Does Electrical Conductivity Make Copper the Better Choice?

Copper becomes more attractive when the machined component itself carries significant current.

In these parts, material selection can directly affect electrical resistance, voltage drop and heat generation.

Current-Carrying Parts vs. Structural Connector Features

Not every feature in a connector assembly performs the same electrical function.

A contact, terminal or conductive block may need to minimize resistance through the current path.

A retaining nut, threaded housing or mechanical connector body may be influenced more by:

• thread quality
• mechanical strength
• assembly reliability
• machining cost

This distinction matters.

Using high-conductivity copper everywhere may increase manufacturing difficulty without improving the performance of features that do not carry meaningful current.

Why Is C110 Copper Used for Conductive Parts?

C110 electrolytic tough pitch copper is a common starting point when high electrical conductivity is the primary requirement.

Typical machined applications include:

• terminals
• conductive blocks
• grounding components
• electrical contacts
• busbar-style connector parts

C110 can provide conductivity around the 100% IACS range depending on condition, making it far more conductive than free-machining brass.

Its main tradeoff is machinability.

High-conductivity copper is soft and ductile. It does not always break into short, clean chips and can be more prone to burrs, edge smearing and difficult chip control.

That does not make C110 unsuitable for CNC machining.

It means the electrical benefit should justify the additional process control.

For more detail on copper grades and manufacturing considerations, see our Copper CNC Machining Services.

When Does CNC Machinability Make Brass the Better Choice?

Brass becomes more attractive when the connector geometry creates much of the manufacturing difficulty.

This is common in parts with fine threads, grooves, multiple turned diameters, bores or repeated small features.

Where Does Brass Help?

C360 free-cutting brass is particularly well suited to precision turned geometry.

Its chip-forming behavior can support:

• reliable thread machining
• cleaner small features
• stable chip evacuation
• shorter cycle times
• consistent repeat production

C360 is commonly used as the reference material for a machinability rating of 100.

Its conductivity, however, is much lower than C110 copper.

So the correct decision is not:

Brass is better because it machines faster.

It is:

Brass is attractive when its conductivity is sufficient and machining complexity is a major part of the finished-part cost.

This can make brass a strong candidate for threaded connector bodies, terminals, inserts and other precision electrical components where maximum conductivity is not required.

For related manufacturing considerations, see our Brass CNC Machining Services.

Is C145 Tellurium Copper the Better Compromise?

For many CNC-machined electrical parts, comparing only C110 copper with C360 brass is too restrictive.

C145 tellurium copper offers an important middle option.

Why Does C145 Matter?

C145 retains much of copper’s electrical performance while machining considerably more efficiently than high-conductivity copper.

Typical published values place it around:

• 93% IACS conductivity
• 85 machinability rating

That creates a very different material balance:

C110
→ conductivity first

C145
→ conductivity + machinability

C360
→ machining efficiency first

When Should You Review C145?

C145 is worth considering for parts such as:

• machined power contacts
• conductive connector pins
• threaded electrical contacts
• switch components
• small precision terminals

Consider a threaded conductive contact that needs small turned diameters, clean threads, tight shoulders and good electrical performance.

C110 may provide excellent conductivity but require more machining effort.

C360 may machine very efficiently but provide less conductivity than the application allows.

C145 can sometimes provide a more practical balance.

Not sure which alloy fits your connector design?
Send the drawing with the current or conductivity requirement, contact surfaces, critical threads and production quantity. We can review the machining tradeoffs before quotation.

Review My Connector Design

How Do Threads, Small Features and Burrs Change the Material Choice?

The material difference becomes more important when a connector includes fine threads, small diameters, grooves, press fits or thin contact features.

Threads and Small Turned Features

Brass generally provides more predictable chip formation than high-conductivity copper.

This can make it easier to produce consistent:

• internal and external threads
• small turned diameters
• narrow grooves
• precision shoulders
• press-fit features

For repeat production of small connector pins or threaded electrical components, these differences can affect both cycle time and process stability.

When the geometry is especially suited to high-volume precision turning, Swiss Machining may also be relevant for small pins, terminals and connector components.

Why Does Burr Control Matter More in Copper?

Copper’s ductility makes it more likely to deform at machined edges rather than fracture cleanly.

This can produce:

• exit burrs
• smeared edges
• rolled material
• poor edge definition

For an electrical component, those defects may affect more than appearance.

A burr can interfere with mating, press-fit assembly, contact area or subsequent plating.

Critical functional edges should therefore be identified on the drawing rather than left under a general cosmetic requirement.

For a deeper discussion, see Why CNC Machined Copper Parts Have Burrs or Poor Surface Finish.

Contact Surfaces Are Not Cosmetic Surfaces

A visually smooth surface is not automatically a good electrical contact surface.

Critical contact areas may require control of:

• mating geometry
• burr-free edges
• contact diameter or flatness
• surface finish
• final plating condition

These requirements should be distinguished from nonfunctional cosmetic surfaces on the drawing.

How Does Plating Change the Brass vs. Copper Decision?

Many electrical connectors are used as plated parts rather than bare brass or copper.

Common finishes include tin, nickel, silver and gold.

Plating changes the material decision, but it does not replace the electrical role of the base metal.

Base Metal and Plating Do Different Jobs

The base metal primarily determines:

• bulk conductivity
• mechanical properties
• machinability
• part geometry

The plating primarily modifies the surface interface, affecting characteristics such as:

• corrosion resistance
• solderability
• contact behavior
• wear resistance

A plated brass part does not gain the same bulk conductivity as a copper part simply because its contact surface is coated.

Likewise, a copper base material may still need plating when the contact interface requires better corrosion, wear or soldering performance.

Plating Must Be Considered Before Machining

Plating thickness changes finished dimensions.

That matters on:

• threads
• press-fit diameters
• connector pins
• mating bores
• precision contact features

A dimension that is correct before plating may no longer be correct afterward.

The drawing should therefore identify the plating type, controlled thickness, masking requirements and whether critical dimensions apply before or after plating.

For small connector parts, even a relatively thin coating can affect fit and assembly.

Which Material Is Better for Common CNC-Machined Electrical Parts?

The following table provides useful starting points.

These are starting points, not material specifications.

The final choice also depends on the required current, temperature rise, mechanical load, mating cycles, plating system and customer-approved material specifications.

Spring contacts may also require other copper alloys that fall outside this machining-focused comparison.

Does Brass Always Cost Less Than Copper for a Machined Connector?

Not necessarily.

Raw material price is only one part of the finished-part cost.

Machining time, burr removal, tool life, inspection, plating, scrap risk and production volume can all affect the final result.

If conductivity requirements allow it, brass may lower finished-part cost by reducing machining time and simplifying thread production.

Copper may still be the better choice when electrical performance controls the design.

C145 creates a third possibility: higher conductivity than brass with much better machinability than C110.

Production quantity also changes the calculation.

For a small prototype batch, the machining-time difference may have limited impact. For thousands of connector pins or terminals, small cycle-time differences can become much more important.

The useful question is therefore:

Which material delivers the required electrical and mechanical performance at the lowest total manufacturing cost?

What Should You Specify for a Brass or Copper Connector Quote?

A complete RFQ helps the machining supplier evaluate both the electrical and manufacturing requirements.

Electrical Requirements

Provide:

• current requirement
• conductivity requirement if controlled
• current-carrying surfaces
• critical contact areas

Material

Specify:

• alloy
• temper if controlled
• approved alternatives if permitted

Avoid specifying only “brass” or “copper.” Different alloys can have very different conductivity and machining behavior.

Geometry

Identify:

• critical threads
• press-fit diameters
• mating features
• connector pins
• burr-free edges
• critical contact dimensions

Plating

Provide:

• plating type
• controlled thickness
• masking requirements
• critical contact surfaces
• dimensions that apply after plating

Quality and Production

Define any required:

• dimensional inspection
• burr limits
• surface requirements
• material certification
• conductivity verification
• plating documentation
• prototype quantity
• expected production volume

These details help determine whether C110, C145, C360 or another approved alloy provides the best balance between electrical performance and manufacturability.

Conclusion

Choose copper when electrical performance drives the design.

Choose brass when its conductivity is sufficient and complex threads, turned features or production efficiency dominate the manufacturing decision.

Review a machinable copper alloy such as C145 when the part needs both high conductivity and complex CNC geometry.

The final choice should consider the electrical function, part geometry, plating and production volume together.

Send your connector drawing with the current requirement, preferred material, critical contact surfaces, plating specification and production quantity so the machining tradeoffs can be reviewed before quotation.

Frequently Asked Questions

Is brass conductive enough for electrical connectors?

Yes, for many connector bodies, pins and lower-current electrical components.

Whether brass is suitable depends on the required current, resistance, section size and allowable temperature rise. Higher-current contacts may require copper or a higher-conductivity copper alloy.

Is C145 tellurium copper easier to machine than C110 copper?

Yes. C145 is used when a part needs much of copper’s conductivity but better machinability than high-conductivity copper.

This can make it useful for complex machined contacts, conductive pins and threaded electrical components.

Should electrical connectors be plated after CNC machining?

Many are, but the correct finish depends on the application.

Tin, nickel, silver and gold are used for different contact, corrosion, soldering and wear requirements. Plating thickness and masking should be defined before machining because they can affect threads, press fits and mating dimensions.