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HA and HA-V2 Foils

The large crystal grain and uniform crystal orientation dramatically improve the flexibility, vibration resistance and other properties of these products compared to ordinary treated rolled copper foil, making them ideal for FPC use. HA and HA-V2 foils are well suited to applications demanding low repulsive force to enable pliability. They are also used for in-vehicle FPC because of their outstanding vibration resistance.

Features

  • High functionality treated rolled copper foil realizing outstanding flexibility
  • Dramatic improvement in vibration resistance
  • Low repulsive force for high pliability
  • Excellent cube orientation

Technical data and properties

Cristal Structure and superior properties of HA and HA-V2

Recrystallized structure

The large crystal grain and uniform crystal orientation of HA and HA-V2 foils give these high functionality treated rolled copper foils outstanding bending performance in static applications, sliding and bending strength (capacity to withstand repetitive bending in dynamic applications), low repulsive force, flexibility, and excellent vibration resistance. The crystal grain is designed to develop into a very large size after annealing, which minimizes cracking by decreasing the area of crystal grain boundaries where cracking can occur.

FIB-SIM views of copper foil cross-section showing differences in crystal structures

Improvement of crystal orientation

HA and HA-V2 foils are designed so that after annealing, the crystalline structure becomes very strongly oriented in the 100 degree direction. This reduces mismatching at the crystal grain boundaries, preventing stress from building up in the foil from bending, vibration, and folding involved in FPC applications, and resulting in a foil that is resistant to metal fatigue and necking.

EBSP views of copper foil surface showing differences in crystal grain orientation

ORIGAMI FPC (evaluation of repetitive bendability)

With special ED foil, cracking appeared in the second cycle, whereas no cracking appeared in TPC foil up to the second cycle, in HA-V2 foil up to the fifth cycle, or in HA foil up to the sixth cycle of testing. HA foil, HA-V2 foil, and TPC foil are superior to the special ED foil in repetitive bendability.

180°cyclic bending test with 0 mm bending radius

Evaluation of repetitive bendability