Add another low-pass filter consisting of an inductor (value depends on the ripple frequency) and a couple of output capacitors (one electrolytic and one ceramic).
Regards,
IanP
Although your capacitance is large, but it doesn't mean it is good
Try to use multiple 1uF or 4.7uF capacitor instead of one 10uF
If it is possible, use SMD rather than through hole
for buck regulator, I think the switch frequency and the output capacitor are the key factor affecting the output ripple.
and, you should pay attention to the type of capacitor. The ESR differs very much for different kinds of cap.
1. Keep short lines between: power transistor and chatchup diode, input filter capacitor and power transistor.
2. Use power plane for GND.
3. Use low ESR capacitor for input and output capacitors.
4. Increase switching frequency.
5. Route carefully feedback lines, and make wise choice of feedback topology.