Polyimide Nonwoven Aramid
Arlon’s 85NT is a pure polyimide with a high glass transition temperature of 250⁰C laminate and prepreg system, reinforced with a non-woven aramid substrate. 85NT combines the high-reliability features of polyimide (improved PTH reliability and temperature stability) with the low in-plane (X,Y) expansion of 6-9 ppm/⁰C and outstanding dimensional stability of the aramid reinforcement. Polymeric reinforcement results in PCBs typically 25% lighter in weight than conventional glass-reinforced laminates. Meets requirements of IPC-4101/53.
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 107°C - 121°C (225°F - 250°F) 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 4.5°C - 6.5°C (8°F - 12°F) per minute between 100°C and150°C (210°F and 300°F). Vacuum lamination is preferred. Start point vacuum lamination pressures are shown in the table below.
- Set cure temperature at 218˚C (425˚F).
- Cure time at temperature = 3.0 hours
- Cool down under pressure at ≤ 6°C/min (10°F/min)
- Drill at 350 - 400 SFM. Undercut bits are recommended for vias 0.023” (0.9cm) and smaller
- De-smear using alkaline permanganate or plasma with settings appropriate for polyimide; plasma is preferred
for positive etchback
- Conventional plating processes are compatible with 85NT
- Standard profiling parameters may be used; chip breaker style router bits are not recommended
- Bake for 1 - 2 hours at 250°F (121°C) prior to solder to reflow of HASL
* Refer to separate process guides for more details.