Introduction

As electronic components rapidly evolve toward miniaturization, multi-polar architectures and high-density packaging, conventional spring copper alloys such as phosphor bronze and ordinary brass are hitting performance ceilings in terms of strength, electrical conductivity and stress-relaxation resistance.
As a technical-oriented supplier specializing in high-precision copper alloy coil and strip, our company responds to global customer requirements: we can supply urgent spot stock as well as long-term bulk volumes for this alloy grade. This article elaborates on the physical properties, fabrication performance and typical applications of C7035 (C70350) copper alloy, supporting engineers working on precision connectors and electronic parts to make superior material selections.

1. C7035 (C70350) Copper Alloy — Breakthrough Performance of Corson-Series Material

C7035 is a classic precipitation-hardened Corson-series copper-nickel-cobalt-silicon copper alloy. Through precise compositional control (Ni: 1.5 %, Co: 1.1 %, Si: 0.6 %, Cu: balance) and mature pre-precipitation heat-treatment processes, C7035 achieves outstanding electrical conductivity and mechanical stability while retaining high tensile strength.
Compared with traditional phosphor bronze (C5210, ~13 % IACS conductivity) or titanium-copper (YCuT, 13-15 % IACS conductivity), C7035 significantly reduces heat generation and power consumption under high-current loads. It serves as an ideal alternative to low-carbon copper (C17510) and titanium-copper alloys.


Core Technical Characteristics
1.Balanced high strength and high electrical conductivity Under TM04 temper, C7035 delivers tensile strength of 770-900 N/mm², yield strength of 750-850 N/mm², alongside high conductivity reaching 48-50 % IACS, achieving an optimal balance of high strength and high electrical performance.
2.Low Young’s modulus & low bending elastic modulus C7035 features Young’s modulus of approximately 120 GPa. Amid the trend toward miniaturized terminals with shorter beam lengths, its low bending elastic modulus effectively mitigates issues including elastic relaxation caused by excessive contact force, high insertion-withdrawal force, and degraded durability after repeated mating cycles.
3.Superior stress-relaxation resistance (high-temperature stability) When subjected to 80 % yield-stress loading for 1000 hours at 150 °C, C7035 (TM04 / TM06) exhibits stress-relaxation rate of only ~5 %. This performance matches NB109, benchmark material for automotive connectors, enabling long-term reliable electrical contact inside engine bays and other high-temperature operating environments.


4.Excellent bending formability Per 90° W-bend test standard JIS-H-3130, C7035 TM04 (t=0.15 mm) achieves R/t=0.0 (zero-radius crack-free bending) for both grain-wise (G.W., longitudinal) and bad-wise (B.W., transverse) directions. It readily handles complex stamping-forming operations, especially for high-density fine-pitch terminal geometries.
5.High purity & environmental compliance Certified by SGS, heavy-metal contents (Pb, Cd, Hg, Cr⁶⁺) measure below 2 ppm. It fully complies with RoHS and stringent global environmental regulations and contains no restricted hazardous elements.

2. C7035 Temper-Grade Performance Specification Table
Based on our internal technical data, multiple tempers are available to satisfy diverse stamping and elastic-performance requirements: