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Is there Lead in you lead free solder pot?

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 Is there Lead in your Lead Free Solder Pot?

 

 solderlab-wave-.jpgThe IPC J-STD-001F Directive maintains that Lead content of circuit boards should not exceed 0.1% by weight of the alloy being used. Cadmium should not exceed .005% under this same directive. Although you may fill your solder pot with "virgin" material in the outset of your manufacturing process, solder can quickly collect "contaminants" that can cause soldering defects, degrade your process quality and put you in danger of non compliance with the IPC Standard. 

Lead contamination is a sneaky thing. It can happen and does happen when you believe your process is fully in control. Lets look at a few factors that contribute to this hidden solder pot killer. 

One common scenario is when Tin Lead finished components or boards are processed in a lead free wave, selective or dip solder pot. Base metals from these tin lead finished parts will readily leach into the solder bath and concentrate over time. Even if you are diligent in matching your base metals to the solder you are using, mistakes can happen. A few good mistakes can include:

  • Engineering, purchasing or distributor oversight in sourcing your components
  • Part Manufacturer process changes to lead frame plating
  • Part shortages that force quick part substitutions 
  • Bad Habits: scrapping tin lead solder paste, wire or solder splashes into a lead free pot
  • Running wave solder fingers through a lead free solder pot after a tin lead run
  • Operator mistakenly replenishes the solder pot with leaded solder

That last point happens more often than expected. Whether this mixup is intentional, or by mistake, many solder manufacturers are taking additional steps to refine their product packaging and form to clearly indicate leaded and lead free products. Only 2 Tin Lead solder bars are enough to raise the lead content of an 800 pound lead free solder pot over the 0.1% ROHS directive limit. 

The EMPF (Electronic Manufacturing Productivity Facility) recommends performing solder alloy testing on a monthly basis to determine the rate at which the solder pot becomes contaminated. After a few months, a test frequency schedule can be determined based on the usage rate of the solder pot versus the solder pot contamination rate (mistakes included). 

SolderLab can assist you in determining how often you should be testing with our flex or PotWatch Solder Testing service. Start here, learn more and get the lead out !