ISU Audio and Arduino Clubs

Soldering hints and links

Soldering hints and tips

(Potential point of confusion: Lead ("led") - element used to make soldering alloys. Lead ("leed") - wire connection of an electronic component.)

• Use lead-tin solder, 40% lead - 60% tin or 37% lead - 63% tin. A diameter of 0.8 mm (0.031 inches) is good for general-purpose soldering with through-hole PCBs.
• Start with a soldering iron temperature of 650°F. Then adjust up or down, as necessary.
• Keep the sponge wet and clean the soldering tip frequently — maybe before every soldering joint. The tip should always be clean and shiny for maximum heat transfer.
• When inserting component leads into the through holes of the PCBs, make sure that the components are seated all the way. For resistors, use needle-nose pliers to pull the resistor leads all the way through so that the resistor is flush to the surface.
• To solder a lead to the through hole, first heat the lead in the through hole with the soldering iron. Wait several seconds to allow the temperature to increase enough so that the solder will melt. Then touch the solder to the lead & through hole. If the metal is heated sufficiently, the solder will melt and flow over the lead and into the through hole. If the solder does not melt onto the lead, pull it back and heat the metal with the iron longer. Do not melt the solder onto soldering iron! Be patient! Once the joint is filled with solder, pull the solder back and then remove the soldering iron. Allow the solder to cool and solidify before moving on to the next solder connection.
• When soldering multi-pin components (chips, sockets, header pins, etc.), start by soldering one pin only. Then check the alignment — make sure the component is flush to the board. If the part is mis-aligned, use the soldering iron to remelt the one joint and then use your other hand to push the part into proper alignment while the solder is liquid. Let the solder cool. Once the part is properly aligned, then solder the remaining pins. Soldering all pins into place and then discovering that the part is mis-aligned is extremely frustrating.
• Soldering a ground lead to a through hole connected to a PCB ground plane can be a bit trickier than other connections. (The ground plane is bigger and harder to heat.) Be patient and let the soldering iron heat even longer. Or try turning the temp up to 700°F or 725°F.
• Use wire cutters to trim away the excess lead on the back side of the PCB. Cut the wire close to the joint, but don't cut into the joint — it is possible to damage it and cause the connection to fail.

A few videos

• youTube 1 (≈ 4 min)
• youTube 2 (≈ 7 min)
• youTube 3 (≈ 16 min)
• EEVblog (part 1) (≈ 27 min)
• EEVblog (part 2) (≈ 34 min)