Arlon’s 49N is a low-flow epoxy prepreg engineered for bonding multilayer epoxy rigid-flex or attaching heat- sinks to multilayer epoxy PCBs. With a high glass transition temperature of 170⁰C, the prepreg can be used in high-performance or high- temperature applications compared to a standard difunctional epoxy low-flow. 49N is well suited for high layer count rigid flex applications where z-axis expansion is a concern. Meets requirements of IPC-4101/26.
Process inner-layers through develop, etch, and strip using standard industry practices. 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 - 45 minutes
- Control the heat rise to about 8°F - 12°F per minute (4.5°C - 6.5°C) between 210°F and 300°F (100°C and 150°C)
- Lamination Pressure: 150-300 PSI (11-21 Kg/cm2) depending on complexity
- Product temperature at start of cure = 360°F (182°C).
- Cure time at temperature = 90 minutes
- Cool down under pressure at ≤ 10°F/min (6°C/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 epoxy; plasma is preferred for positive etchback
- Conventional plating processes are compatible with 49N
- 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 reflow or HASL