What is the heat-resistant temperature for a relay when manually soldering, and what are the precautions for manual soldering?

1. After smoothing the iron tip, solder according to the following conditions:
   
   • Soldering iron: 30 to 60 W
   • Iron tip temperature: 350°C
   • Soldering time: Within about 3 seconds
2. Use non-corrosive rosin for the flux because of the compatibility with the relay components.
   Use an alcohol solvent with less chemical action for flux.
3. When soldering the terminals, make sure that no solder, flux, or solvent adheres to any part other than the terminals. If solder, flux, and/or solvent enters the inside, it could cause insulation degradation and poor contact.

For more information, see Safty Precautions for All Relays: 6-10 Automatic Mounting of Relays for PCBs.

Note that, as shown in the figure below, some solders have a cut surface to prevent flux from scattering.