DESIGN FOR MANUFACTURING (DFM) GUIDE

Designing for Electrical Properties

Choosing a material with the right electrical performance is critical for any electronic product. This guide covers the fundamentals of conductive and insulating materials.

A precisely machined copper busbar used for conducting electricity

Conductive Materials

Conductive materials allow electricity to flow through them easily. Their performance is measured by **conductivity** (how well they conduct) or its inverse, **resistivity** (how much they resist flow). Materials with low resistivity are good conductors.

Common Conductors:

Copper (C110, C101): The standard for electrical applications due to its excellent conductivity, second only to silver. Used for bus bars, contacts, and wiring.
Aluminum (6061): A good conductor, though not as efficient as copper. Its light weight makes it ideal for large-scale power transmission lines and some heat sinks.
Brass (C360): A decent conductor that is much easier and cheaper to machine than copper. Used for terminals, connectors, and pins.

An industrial fixture made from insulating plastic to hold a PCB

Insulating Materials (Dielectrics)

Insulating materials, or dielectrics, do not allow electricity to flow through them. They are used to isolate conductors and prevent short circuits. Their performance is measured by **dielectric strength** and **surface resistivity**.

Common Insulators:

POM (Delrin®): Offers excellent stiffness and high volume resistivity, making it a great choice for electrical insulators, switches, and connectors.
PEEK: A high-performance insulator that maintains its properties at very high temperatures, ideal for demanding aerospace and downhole connectors.
ABS & PC: Commonly used for electronic enclosures and housings that isolate internal components from the user.

Key Electrical Properties Explained

Dielectric Strength

This is the maximum electric field an insulating material can withstand without "breaking down" and becoming conductive. It's measured in Volts per unit of thickness (e.g., V/mil). A higher dielectric strength means a better insulator. This is critical for high-voltage applications.

Volume & Surface Resistivity

Volume Resistivity measures how strongly a material opposes the flow of electricity through its bulk (volume). Surface Resistivity measures how strongly it opposes flow across its surface. Both are measured in Ohm-meters (Ω·m) or Ohm-squares (Ω/sq). High values indicate a good insulator.

Static Dissipative vs. Anti-Static

These terms are important for protecting sensitive electronics from electrostatic discharge (ESD). Anti-Static materials simply prevent the buildup of a static charge (like an insulator). Static Dissipative materials are slightly conductive, allowing a static charge to flow to ground slowly and in a controlled manner, which is safer for sensitive electronics. We can source special ESD-safe grades of plastics for applications like PCB handling fixtures.

Electrical Properties FAQ

Does anodizing affect the conductivity of aluminum?

Yes, critically. Anodizing creates a layer of aluminum oxide, which is an excellent electrical insulator. Anodized aluminum will not conduct electricity. If you need a part to be conductive for grounding purposes, you must specify that certain areas be masked to prevent them from being anodized.

Which plastic is the best electrical insulator?

For general purposes, plastics like POM (Delrin), PTFE (Teflon), and PEEK have some of the highest dielectric strengths and volume resistivities, making them excellent choices for high-performance electrical insulators.

Can you machine G10 or FR-4 composite materials?

Yes, we can CNC machine thermoset composite materials like G10/FR-4. These are glass-epoxy laminates widely used for circuit boards, insulators, and test fixtures due to their high mechanical strength, dimensional stability, and excellent electrical insulating properties.