FPC Cable Manufacturer for Australian OEM Programs

Stackup and bend-zone reference

Specify the complete local stack, not just the polyimide film. A single-layer flex has one copper circuit layer; a double-layer flex has copper on both sides of a dielectric. Coverlay protects the traces, with openings for contacts. Base laminates can use adhesive between copper and film or an adhesiveless construction. Stiffeners add local support at terminations; they are not another circuit layer.

DuPont Pyralux AP is an adhesiveless double-sided polyimide laminate. Its table lists AP8515R with 18 µm copper and 25 µm dielectric, and AP9111R with 35 µm copper and 25 µm dielectric. The R suffix identifies rolled-annealed copper. These are named material examples, not a finished FPC thickness or this assembler's capability range. Account separately for coverlay, adhesive, plating and any shield.

DuPont Pyralux LF coverlay uses Kapton polyimide film coated with modified acrylic adhesive for insulation and protection of etched circuitry. An adhesiveless base laminate can still use an adhesive-backed coverlay. Select the exact material codes and released construction before calculating finished thickness.

Sources: DuPont Pyralux AP, Tables 1–2; DuPont Pyralux LF coverlay; Minco guide, pp. 4 and 13.

Static routing and repeated motion need different reviews

Static flex is formed for installation; dynamic flex moves repeatedly in service. Minco advises traces perpendicular to bend lines, consistent trace width through the bend, no plated through-holes in bend areas, and continuous cover material near a bend. Support terminations with local stiffeners and review strain relief at their edges. Coverlay protects the circuit; extra reinforcement through a moving zone must not be assumed to improve flex life.

Epec recommends rolled-annealed (RA) copper for dynamic flex rather than ordinary electrodeposited (ED) copper, citing its more ductile, elongated grain structure. Agree rolling direction with the flex supplier. Motion, layer arrangement and shielding also require review; copper type alone does not qualify repeated bending.

Sources: Minco guide, pp. 12–13 and 24; Epec dynamic-flex guidance.

Bend radius: material basis and assumed calculation

Use R = k × t, where t is the finished thickness at the bend, including applicable coverlay, adhesive and shield layers. It is not copper thickness alone or the reinforced connector-end thickness. Minco lists a double-layer minimum of 12 × circuit thickness in its static-flex discussion; Epec gives 100 × finished dynamic-area thickness as dynamic-flex guidance. These are supplier recommendations for different duties, not universal rules or a numerical requirement verified from IPC-2223.

Assumed example only: select t = 0.10 mm for illustration, not from either DuPont laminate row. With an assumed applicable static multiplier k = 12, R = 1.20 mm. With an assumed applicable dynamic multiplier k = 100, R = 10.00 mm. The arithmetic compares recommendations; it does not qualify a design or establish a bend-cycle count. Confirm construction, radius datum, motion and acceptance testing with the flex supplier.

# Assumed finished thickness; supplier-guidance comparison only
from decimal import Decimal
thickness_mm = Decimal("0.10")
for duty, multiplier in [("static", 12), ("dynamic", 100)]:
    print(f"{duty}: t={thickness_mm:.2f} mm, k={multiplier}, R={thickness_mm * multiplier:.2f} mm")
# static: t=0.10 mm, k=12, R=1.20 mm
# dynamic: t=0.10 mm, k=100, R=10.00 mm

Sources: Minco guide, pp. 12–13; Epec minimum bend-radius guidance. The IPC-2223E public contents confirms the flexible-board design standard's scope; use the contractually specified edition for detailed requirements.