Bonded Copper Conductors for Use in Hookup Wires for Electronic Equipment

B470: Standard Specification for Bonded Copper Conductors for Use in Hookup Wires for Electronic Equipment

In the intricate world of electronic equipment design and manufacturing, the reliability of every component is paramount. For engineers and designers specifying materials for hookup wires, understanding the foundational standards that govern conductor quality is essential. ASTM B470 provides that essential framework, offering a comprehensive specification for bonded copper conductors, ensuring consistent performance and durability in demanding applications.

What is B470?

ASTM B470 is an authoritative industry standard that defines the requirements for stranded, uninsulated copper conductors used in hookup wires for electronic equipment. Developed by ASTM International, it specifically addresses conductors where the individual wires within the strand are metallically bonded together, typically through heat or tinning. The primary purpose of B470 is to establish material, construction, and performance criteria to ensure these bonded conductors meet the rigorous demands of electronic applications.

Scope & Purpose

This standard governs the material composition, construction, and testing of stranded copper conductors designed for bonding. It covers bare copper, as well as tin or tin-lead alloy coated copper conductors, specifying different bonding levels ("light" and "heavy") to suit various flex-life requirements. The scope includes conductor properties such as flex life, resistance to fraying, and dimensional tolerances. Importantly, B470 does not cover insulated conductors or the complete hookup wire assembly, focusing solely on the bonded copper conductor itself.

Who Must Comply?

• • Primary audience: Materials Engineers, Electrical Engineers, Quality Control Inspectors, and Manufacturing Engineers involved in the design and production of electronic equipment.
• • Industries affected: Electronics, Telecommunications, Aerospace, Industrial Automation, and any sector utilizing electronic hookup wires.
• • Compliance nature: Primarily voluntary, but often mandated by purchasers and end-users within their own specifications to ensure product quality and reliability.
• • Enforcement: Typically enforced through contractual agreements between suppliers and purchasers, and verified by quality assurance departments or third-party inspectors.

Key Requirements Overview

ASTM B470 outlines several critical requirements for bonded copper conductors:

• • The standard necessitates that conductors conform to the material and construction principles of related ASTM specifications, such as B3 for bare copper and B286 for hookup wire conductors.
• • It specifies different types of bonding—light and heavy—which directly influence the conductor's flex life performance.
• • Rigorous testing protocols are defined, including flex tests to evaluate the conductor's ability to withstand repeated bending, and fraying tests to assess strand integrity.
• • For heavy bonding (Type III), a mandrel test is included to ensure the bonded strands maintain their structure when wrapped around a specified diameter.
• • Conductor resistance must meet the established criteria outlined in referenced standards, ensuring electrical integrity.

Related Standards & References

ASTM B470 works in conjunction with other key standards to provide a comprehensive material specification:

• • ASTM B3, Specification for Soft or Annealed Copper Wire: This standard provides the foundational requirements for the bare copper wire used as the base material before bonding.
• • ASTM B286, Specification for Copper Conductors for Use in Hookup Wire for Electronic Equipment: B470 references B286 for general conductor constructions and electrical properties, layering its specific