July 6, 2006

RoHS overview

This year and the coming years will be challenging for electronic industry. As the July 1 RoHS deadline has come into force, no new equipment sold in EU may contain certain levels of six toxic metals: lead (Pb), mercury (Hg), hexavalent chromium (Cr (VI)), cadmium (Cd), polybrominated biphenyls (PBBs), and polybrominated diphenyl ethers (PBDEs).

Of course it is a noble idea to make electronics environmental friendlier and its recycling easier and safer. However in reality it will take years until we see all consequences of implementation of RoHS (The Restriction of Hazardous Substances) Directive. It is worth noting that the EPA report on Solders in Electronics: A Life-Cycle Assessment (August 2005) suggests that the lead-free solder replacements will have a higher environmental impact than tin lead solder in a number of areas including global warming, ozone depletion and water quality.

I also wonder what will happen with all existing non-RoHS part inventory. I guess some of them will wind up in the landfill. Others (as my boss suggested) may return to the open market through third world countries as counterfeit RoHS-compliant parts. Indeed, many manufacturers do not change part numbers and marking when they make the transition to RoHS products. For such parts, the only way to determine whether it is really RoHS-compliant is to compare its date code to the manufacturer's conversion date- something you can't do for small package sizes with no date code marking on the part itself.

The biggest challenge of course is switching to lead free solder. The main issues with lead-free allows are:

  • Tin-lead alloy has melting point of 361 F (183 C). The typical alternative alloys have melting point higher by at least 63 F (17 C). The higher temperature could damage PCBs and other components, which requires changing in the manufacturing process and materials.
  • In alternative alloys, liquid solder may not attach itself to a surface as good as tin lead allow (poor "wetting")
  • Possibility of "tin whiskers" (effect of growing tiny metal "hairs")
  • Nobody but nobody knows long-term reliability effect of new solder

Fortunately, RoHS directive has exceptions for a number of critical categories that cannot afford any risk, such as aviation and military equipment, most medical devices, and large-scale industrial tools. Server, network and telecommunication infrastructure equipment can continue using lead in solder until 2010 and still be RoHS-compliant (so called RoHS-5 or "lead exempt"). The rest of equipment, particularly general purpose power supplies with a voltage rating below 1000 VAC / 1500 VDC not falling into the above categories has to comply.

So, what does all this mean for the electronic industry?
I guess until the dust settles we may frequently see: delayed shipments as manufacturers struggle to weed out non-compliant parts and change manufacturing process, worse financial reports, unpredictable quality issues especially with manufacturers who do not have advanced product screening system (such as HASS) in place.

Well, whatever it takes to satisfy European lawmakers (-:

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