Arlon’s 45NK is a woven Kevlar® aramid fiber reinforced multifunctional epoxy laminate and prepreg system engineered to provide in-plane CTE values as low as 6 ppm/°C. Provides compatibility with leadless alumina ceramic chip carriers (LCCC’s) and other low expansion SMT devices where control of laminate expansion is critical for solder joint reliability. Meets requirements of IPC-4101/50 (AFN).
Process inner-layers through develop, etch, and strip using standard industry practices. Use brown oxide on inner layers. Adjust dwell time in the oxide bath to ensure uniform coating.
Bake inner layers in a rack for 60 minutes at 225°F - 250°F (107°C - 121°C) immediately prior to lay-up. Vacuum desiccate the prepreg for 8 – 12 hours prior to lamination.
- Pre-vacuum for 30 minutes
- Control the heat rise to 8°F-12°F (4.5°C - 6.5°C) per minute between 210°F and 300°F (100°C and 150°C)
- Product temperature at start of cure = 360°F (180°C).
- Cure time at temperature = 90 minutes
- Cool down under pressure at ≤ 10°F/min (5°C/min)
Kevlar® fabric compresses and distorts under pressure, more so than E Glass, which dictates the use of lower lamination pressures. The use of an autoclave or vacuum assist lamination makes the use of lower pressure possible. Typically the pressures used under vacuum should be about 50% of those used for standard press lamination e.g. 12” x 18” (30 cm x 46 cm) panel non-vacuum 300 PSI
(2 kg /cm2) versus vacuum 150 PSI (10.5 kg/cm2).