WASTE ORIGINS: Board Preparation, Electroless Plating, Imaging, and Electroplating
WASTE TYPES: Spent Process Baths (Etchants, Acid Solutions, Alkaline Solutions, Developing Solutions, Plating Baths, Electroless Copper Baths, Catalysts) Air Emissions (Volatile Organic Compounds, Acid Fumes, Ammonia Fumes) Sludges, Rinse Waters, and Aqueous Metals

WASTE REDUCTION AND RECYCLING OPTIONS:

• Process or equipment modifications can reduce wastes by:
  • Modifying sludge pretreatment processes by:
    Adding flow control valves;
    Installing metal recovery equipment;
    Adding deionization system;
    
  • Installing a system (e.g., CALFRAN process) to reduce pressure of vaporization at cooler temperatures, recycle water by condensing the vapors in another container, concentrate, and precipitate solutes.
    Waste Savings/Reduction: reduce volume and quantity of aqueous waste solutions by recovering pure water.
  • Alternatives to wet chemical processes include:
    • Mechanical cleaning as an alternative to chemical methods;
    • Process efficiency improvements for applying photopolymers, printing, and developing;
    • Alternative processes for connecting the PWB layers together; and
    • Alternatives to lead-based soldering involving the use of lasers, reactive gases, or ultrasonics.
• Raw material substitution can reduce wastes by:
  • Substituting semiaqueous or aqueous photoresist for TCA and methylene chloride resists.
  • Substituting no-clean fluxes.
  • Substituting aqueous clean fluxes.
  • Substituting semi-aqueous cleaning materials.
  • Substituting other solvents for CFC 113 and TCA during board assembly.
• Waste separation or preparation can reduce wastes by:
  • Separating wastewater sludge to prepare for metal recovery.
• Recycling can reduce waste by:
  • Removing and recovering lead and tin from boards by electrolysis-chemical precipitation.

Sources

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