The following is based on the industrial manufacturing end and consumer recycling end of the PCB classification and details, covering solid, liquid and special form of waste, all information is from the 2025 authoritative industry data and technical reports:
Sources from PCB classification production and electronic assembly, with concentrated composition and high metal content:
1. PCB milling chips
Source: chips and powders generated from PCB sheet cutting, drilling and milling.
Composition: copper particles (30%-60%), epoxy resin chips, glass fiber and trace gold/silver (from surface plating).
Recycling value: physical crushing + eddy current sorting, copper recovery rate > 96%, value of about ¥ 20,000-¥ 45,000 / ton.
2. Flexible Printed Circuit Board (FPC) Edge Material
Source: Edge waste generated when FPC is cut and molded.
Composition: Polyimide base material (40%), copper foil (35%-50%), adhesive and nickel/gold plating.
Characteristics: light and thin, easy to wind, need special shear crusher pretreatment, pyrolysis temperature should be controlled at 380-450 ℃ to avoid cyanide generation.
3. Etching waste liquid and micro-etching waste liquid
Source: PCB line graphic etching process waste liquid.
Composition: high concentration of copper ions (80-150g / L), ammonia or acidic copper chloride; micro-etching solution containing persulfate and copper residue.
Recovery value: chemical precipitation/electrolysis copper extraction, 800 tons of copper can be extracted from every 10,000 tons of waste liquid (in the form of alkaline copper chloride or copper sulfate).
4. Copper-containing sludge
Source: Sediment from PCB factory wastewater treatment.
Composition: copper (15%-30%), tin, nickel hydroxide mixture, water content of 70%-90%.
Treatment technology: microbial leaching (copper leaching rate of > 99%) or pyrometallurgical smelting after press-filter drying, valued at about ¥ 9,000-¥ 18,000 / ton.
from the dismantling of end-of-life electronic products, the composition is complex but high value of precious metals:
1. Whole machine dismantled PCB
High-value boards: server/communication equipment motherboards (multi-layer, including gold fingers, BGA package), gold content 200-500ppm, palladium 50-200ppm, priority fire smelting to extract precious metals.
Common boards: Home appliance/consumer electronics motherboards (single and double sided), 15%-25% copper, leaded tin solder, suitable for physical pulverization or supercritical methanol degradation.
Special type:
Aluminum substrate: LED lamps and lanterns heat dissipation substrate, metal layer of aluminum + copper foil, need to be separated and recycled.
Immersion gold plate: surface gold plating process (gold layer 0.05-0.1μm), cyanide leaching gold recovery rate > 99%.
2. Component separation waste
Reusable components: CPU, memory chips (refurbished for repair market).
Components containing precious metals:
SMD capacitors (palladium/silver end electrodes);
Gold wire bonded chips (98% gold wire);
Plug-in devices (gold-plated contacts), precious metal recycling dominated by fire melting.
3. New biodegradable PCB scrap (Soluboard)
Source: Plant fiber substrate demo/evaluation boards from Infineon and other manufacturers.
Characteristics: 90 ℃ hot water immersion for 30 minutes decomposition, component recovery rate of > 90%, residual fiber can be composted, but the cost is 50% -75% higher than FR-4, not large-scale application.
Mainly from the separation of resin and fiber in the recycling process:
1. Epoxy resin-glass fiber mixture
Source: Non-metallic residue after physical sorting (35%-40% of PCB weight).
Recycling technology:
Supercritical methanol degradation: 350°C/90 minutes to break down the resin to produce a non-brominated phenolic liquid, with non-destructive recovery of the glass fibers.
High temperature cracking: 92.3% cracking rate under nitrogen environment at 800°C, producing light oil with calorific value of 42.6MJ/kg and glass fiber with purity of 96.7%.
2. Brominated flame retardants (BFRs) residues
Source: By-products of resin degradation process.
Risk control: fully enclosed negative pressure conveying + deodorant spray tower, so that the emission of hydrogen bromide <15ppm (national standard limit of 50ppm).
1. Pre-treatment requirements: consumer PCB need to manually remove the battery, plastic shell (to avoid incineration release of dioxin); industrial trimmings need to remove protective film and tape.
2. Pollution control: chemical recycling must be closed to deal with acidic waste gas (such as HBr) and cyanide wastewater; physical sorting needs to be equipped with dust removal equipment (dust containing flame retardants).
3. Compliance: The new EU WEEE 2025 regulation requires Printed Circuit Board Recycling rate ≥ 85%, modular design, separable soldering materials and digital tracking code (DTC).
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