Friday, 26 February 2010 18:49

Probable Causes of Soldering Iron Tip Failure

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Probable Causes of Soldering Iron Tip Failure

There are many factors that influence soldering iron and tip life. Tips life will depend on proper maintenance, cleaning, temperature, tip configuration, and the jobs being done. Get the best performance from your iron and maximize tip life by following these simple suggestions and precautions. For soldering iron and tip care suggestions go to tipcare.htm.

  1. Make sure you have the correct amount of voltage in your line for your iron. Most irons are designed to handle slightly varying supply voltages but a consistently high line voltage will cause the iron to run hot and reduce tip life.
  2. The higher the tip temperature, the faster oxidation forms. Soldering at temperatures over 875º F causes your iron tip to oxidize twice as fast as soldering at 700º F. Adjust your soldering temperature to the minimum temperature needed to melt your solder and have it flow smoothly.
    Alloy Tin ‰ Lead ‰ Solid to Liquid at Pasty Range
    50/50 50 50 361º 421º 60º
    60/40 60 40 361º 374º 13º
    63/37 63 37 361º 361º  0º
    • 60/40 Solder: Composed of 60% tin and 40% lead, this solder melts at 374 ºF, but doesn't become completely solid until it cools to 361ºF. This means it has a "pasty range" or "working range" of 13 degrees. 

    • 50/50 Solder: This is composed of 50% tin and 50% lead. It is liquid at 421ºF, solid at 361ºF and has a pasty range of 60 degrees. 

    • 63/37 Solder: This solder is 63% tin and 37% lead. It becomes liquid at 361ºF, and solid at 361ºF, with a pasty or working range of 0 degrees. This solder is called a eutectic alloy which means at 361ºF, you can go instantly from solid to liquid to solid just by applying or removing the heat source. 

    • Lead-Free Solder: Depending on the specific mix of metals, lead free will produce differing liquid, solid, and pasty range temperatures. Check with the solder manufacturers for these specifics. 

  3. Keeping the tip clean is important but constantly wiping it on a wet sponge can cause early tip failure. Wiping causes the tip temperature to drastically rise and fall and the different metal layers in the tip to repeatedly expand and contract. This cycling leads to metal fatigue and ultimately tip collapse. The more frequently you wipe the tip, the more you stress it.
  4. Pushing the solder into the tip to force it to melt or rubbing the tip against the joint to force heat in will destroy the tip faster. Allow the iron to heat to the soldering temperature where normal contact of the solder with the tip causes the solder to melt.
  5. The lower the tin content of the solder, the more difficult it is to keep the tip from loosing its protective coating of solder (dewetting). Keep a roll of large diameter 63/37 on hand to periodically flush and re-tin your iron tip.
  6. Match the diameter of the solder to the tip. Using small diameter solders may not keep the tip flooded with solder while in use and cause the tip oxidize and wear faster. Use large diameter solder or periodically flood and tin the tip using large diameter 63/37 solder as suggested above.
  7. The more active the flux, the faster oxidation on the tip forms requiring more frequent tip cleaning. Using a flux with the lowest activity possible will help reduce oxidation and corrosion and maximize tip life.

For a list iron and tip maintenance suggestions go to Soldering Iron and Tip Care.

 

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