Good Solder SAC305 in fine wire format with flux core. I still prefer Sn99.3/Cu0.7 heat flux (probably nickel stabilized) as it makes shinier joints and seems better/faster/stronger than SAC305. While Sn99.3/Cu0.7 requires higher temperatures, I believe the time window can be significantly narrowed in hand soldering due to the better flow of Sn99.3/Cu0.7. Unfortunately, I couldn't find Sn99.3/Cu0.7 with a diameter of 0.02" or less, so I used this material instead.