Arlon’s 44N is a high resin content multifunctional (175°C) epoxy prepreg system with a proprietary microdisperse ceramic filler system. 44N is engineered for the filling of clearance holes in thin metal cores such as 0.006″ Copper-invar-Copper or via holes in sequentially laminated MLB designs. Based on Arlon’s 45N, the 44N system is compatible with conventional epoxy lamination and fabrication. Meets requirements of IPC-4101/98.
We suggest the use of vacuum or vacuum assist lamination. Pressure, temperature and time may vary depending on the available equipment, panel size and complexity and other factors.
Controlling the heat-up rate, of the multilayer package, to 8-12°F/4-7°C per minute between 150°F and 300°F/65-150°C is recommended. See start point recommendations for pressure in table below:
A 90 minute cure at a temperature of 365°F/185°C should achieve a Tg of >170°C. When the lamination package contains layers of metal core, the cure time may need to be extended to offset the heat lagging effects of the metal.
NOTE: for sequential lamination use 60 minutes for the first lamination and 90 minutes for the final. Cool down under pressure at < 10°F/min (5.5°C/min). Cool down at < 5°F/min (3°C/min) can enhance reliability and resistance to cracking.
- Drill at 350 SFM. Undercut bits are recommended for vias 0.018” (0.45cm) and smaller De-smear using alkaline permanganate or plasma with settings appropriate for FR-4. slightly longer dwell times may be needed for multifunctional compared with difunctional FR-4.
- Bake for 1 – 2 hours at 250°F (121°C) prior to solder reflow or HASL.