Materials and Finishes

Selecting the correct material for your application with the required properties in terms of mechanical, thermal, electrical, environmental and cost considerations; is vitally important. Key factors both in the choice of material and the general design of the flexible circuit are.

The following are some examples:

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  • Continuous operating temperature
  • Current carrying capacity
  • Shielding requirements
  • Flex life
  • Insulation resistance
  • Characteristic impedance
  • Flammability
  • Voltage drop

Conductors

The most common conductor used in the manufacture of flexible circuits is copper. Copper foil is available in two forms - Rolled Annealed (RA) and Electrodeposited (ED). Electrodeposited copper is the most cost-effective material and is more widely used for the majority of applications. Rolled annealed copper has excellent elongation and is best suited to high dynamic flexing applications. Supplied as a polyimide based laminate, the copper foil is available in standard thickness of 5, 9, 12, 18, 35 & 70 microns. Pure copper foils are available in a thickness from 18 microns up to 250 microns. Alternative conductor materials such as Aluminium, Nickel & Beryllium copper are available.

Polyimide

There are many different dielectric materials available for the manufacture of flexible circuits. Flex-Ability specializes in Polyimide film, which has become well established and commercially available in standard thickness of 12.5, 25, 50, 75 and 125 microns. Polyimide laminates are outstanding in their ability to meet the majority of the above requirements. The combination of polyimide film, thermosetting adhesive and copper foil produces a flexible solution which achieves continuous operating temperatures from -55°C to +125°C and the ability to have a UL released flame retardant system.

Polyimide (Adhesiveless)

For flex/rigid multilayers and high-density fine pitch flexible circuits, adhesiveless laminates should ideally be utilized. This technology eliminates the adhesive layer between the copper and polyimide (either by the copper placed directly onto the polyimide film or the polyimide coated directly onto the copper foil) resulting in higher operating temperatures 180°C and exceptional physical properties. Adhesiveless laminate systems are available in 12.5, 25, 50 micron polyimide (Kapton and Upilex) and in copper foil at 5, 9, 12, 18, 35 & 70 microns.

Other Materials Available

PEN / Polyester / PET / FEP (Teflon) / Silver Polymer Inks Further details on the above materials are available upon request.