CHAPTER 21 ■ SOLDERING EQUIPMENT
For circuit-board work, look for solder wire with a thickness of #21 AWG or #22 AWG (American wire gauge),
usually stated as around 0.75-millimeter or 0.032-inch diameter. For health reasons, always use lead-free solder,
which is commonly a mix of tin, silver, and copper.
Solid-core solder consists only of solder throughout the entire wire, whereas cored solder contains flux
in the center. Flux is a chemical that dissolves oxides on the metal during soldering. The removal of surface
oxides greatly improves the joint connection. Choose solder containing a core of mildly activated rosin flux
or no-clean rosin flux.
■ Caution Never use acid-flux core solder on electrical components. Also avoid organic or highly activated
rosin flux unless the circuit is then thoroughly cleaned according to the flux manufacturer’s instructions. Unless
completely removed, those fluxes can erode or degrade electrical components and their connections over time.
Table 21-1 lists a couple of sources of 0.031-inch diameter, no-clean, flux core, lead-free, solder wire.
The same type of solder in a slightly larger diameter is an acceptable substitute.
Flux
Besides appearing in the core of solder, liquid and paste flux is also available separately (see Figure 21-3).
Applying a bit of flux to grungy or stubborn joints is the secret to high-quality soldering. Whenever I am
unable to solder a particular location, I’ll dab a little bit of flux onto the spot and try again.
Figure 21-2. Lead-free solder wire
Table 21-1. Suppliers of Lead-Free Solder Appropriate for Robot Circuit Boards
Supplier Part Number Price Quantity Description
SparkFun TOL-09163 $3.50 10 grams Solder Lead-Free 10-gram Tube
SparkFun TOL-09325 $7.95 100 grams Solder Spool - Lead-Free
Mouser 738-14048 $40.31 1 pound SAC305 Glowcore
Digi-Key KE1137 $122.39 1 pound 0.031-Inch Lead-Free No-Clean Core Solder