Chemical Limitation
Mandatory concentration limits prohibit specific hazardous elements and chemical compounds from homogeneous materials used in electrical and electronic equipment. RoHS restricted substances comprise ten regulated entities, including heavy metals such as lead, mercury, cadmium and hexavalent chromium, alongside specific brominated flame retardants and phthalate plasticizers. International legislation enforces these thresholds to reduce electronic waste toxicity and improve end-of-life recycling safety.
Material Thresholds
Regulatory enforcement permits a maximum concentration of 0.01 percent by weight for cadmium and 0.1 percent for lead, mercury, hexavalent chromium, polybrominated biphenyls, polybrominated diphenyl ethers, and four specific phthalates (DEHP, BBP, DBP, DIBP). These limits apply to every individual homogeneous material within an assembly rather than the total product weight. Lead-free solder transitions replaced traditional tin-lead alloys with tin-silver-copper formulations to eliminate lead from surface mount interconnects.
Specific exemptions permit restricted substances where viable technical alternatives do not exist, such as lead in high-melting-point solders or copper alloys containing up to four percent lead by weight. Compliance verification uses energy-dispersive X-ray fluorescence screening followed by destructive chemical analysis via inductively coupled plasma mass spectrometry for ambiguous samples. Suppliers must substantiate declarations with technical files demonstrating conformity to the list of RoHS restricted substances.
Supply Chain Verification
Component obsolescence and unauthorized material changes introduce non-compliant substances into production lines without design engineering awareness. Incoming material inspection and periodic laboratory audits verify that raw components satisfy environmental directives. Certified manufacturing processes prevent toxic heavy metal contamination across commercial electronics hardware.
