Presentation is loading. Please wait.

Presentation is loading. Please wait.

1 ESM 595 F Pollution Prevention in the Electronics Industry.

Similar presentations


Presentation on theme: "1 ESM 595 F Pollution Prevention in the Electronics Industry."— Presentation transcript:

1 1 ESM 595 F Pollution Prevention in the Electronics Industry

2 2 Electronics Industry zFast growing sector of economy zFew common appliances and machines could function without electronics zPerceived as “pollution-free” since it has no smoke stacks zEnvironmental impacts...

3 3 Semiconductor Manufacture zCrystal Growth zWafer fabrication zDeposit of active and inactive layers zOxidation to form silicon oxide zPhotolithography zEtching zAddition of impurities for special functions

4 4 Crystal Growth

5 5 Silicon Wafer

6 6

7 7 Printed Circuit Board zPatterns of Conductive Material set on a Non-conductive base zConductive Materials: Cu, Al, Cr, Ni zNon-conductive: Epoxy/paper, phenolic resin, epoxy/glass resin, teflon zConductor can be added as lines or as a layer which is then etched

8 8 Printed Circuit Board zClean and prepare surface (drilling, burring, solvent wash, abrasive wash, alkaline wash) zElectroless copper plating (thin layer through holes) zPattern printing and masking zElectroplating zEtching

9 9 Circuit Board Assembly zInsert components zAdhere components zCure adhesive zSolder zFinal cleaning

10

11 11 Other Process Considerations zPiping of gases and corrosive liquids zCooling water to control processing temperature zDeionised water production zClean room conditions zHandling of process wastes (gas, liquid, solid)

12

13 13 Waste Streams

14 14 Waste Streams

15 15 Waste Streams

16 16 Example: Copper Waste

17

18 18

19

20

21 21

22

23 23 Environmental Impacts zFrom Manufacturing yAir emissions yWastewater ySolids, sludges and Haz wastes zFrom Product Use yEnergy (electrical or batteries) zFrom Product Disposal

24 24 Example: Pager zDisposed due to yend of useful life yobsolescence zTo recover useful materials, need to consider: ylabor to disassemble ysegregated storage & transportation yreprocessing zBalance against scrap value of materials

25

26 26 Example: Pager zCircuit board is sent to a reclamation facility yburn off organic materials (epoxy, paper) yrecover metals: Au, Ag, Pt, Pd, Cu, Al, Ni, Cr yGold may represent less than 1% but account for more than 90% of value yEstimated value of average circuit board is $7 per pound ($3/kg) (1992 prices)

27 27 Example: Pager zOther reusable parts yvibrator motor ymicroprocessor yoscillator crystals yfilters ycoils yantennae zValued at $19.28 zWarranty, obsolescence, disclosure

28 28 Pollution Prevention Tools zLife-Cycle Assessment/EIA zProduct Design yHigher density of transistors in each chip yHigher density Surface Mount Technology vs. conventional plated-hole technology yUse more common plastics yReduce plastics/metals assemblies yUse built-in plastic or metal clips for assembly

29 29 Pollution Prevention Tools zProcess Design yVacuum pack after epitaxy yIron oxide masks (vs. emulsion masks) ySingle solvent systems (recover/reuse) yWater based developer (vs. solvent) yInfrared heating lamps for drying yFiltering plating, etching baths yDry etching vs. wet etching

30 30 Pollution Prevention Tools zMaterial Selection yAqueous cleaning materials vs. solvents yPurification of solvents yEliminate use of CFCs by substitution yReduce number of acids, and use those that result in non-toxics when neutralized (e.g. HCl vs. Trichloroacetic acid) yLead-free solder

31 31 Pollution Prevention Tools zOperational Factors yProcess Control yPreventive maintenance yMonitoring of concentrations in air & water yMaterials handling & storage yInventory control

32 32 Pollution Prevention Tools

33 33

34 34 Pollution Prevention Tools

35 35 Waste Stream Processing

36 36 Waste Stream Processing

37 37 Waste Stream Processing

38 38 Waste Stream Processing

39 39 Step-by-Step Case Study zCase Study of Pollution Prevention for Printed Circuit Board zPhase I: Preassessment yStep 1: Form audit team & develop objectives yStep 2: List Unit Operations yStep 3: Construct Process Flow Diagrams with emissions and waste streams

40 40 Case Study of Pollution Prevention for Printed Circuit Board

41 41 Case Study of Pollution Prevention for Printed Circuit Board

42 42 Case Study of Pollution Prevention for Printed Circuit Board zPhase 2: Material Balances yStep 4: Determine Inputs yStep 5: Record Water Usage yStep 6: Determine Reuse/Recycle Rates yStep 7: Quantify Process Outputs yStep 8: Characterize wastewater streams yStep 9: Account for gaseous emissions yStep 10: Account for off-site wastes yStep 11: Assemble Input + Output Information

43 43 Case Study of Pollution Prevention for Printed Circuit Board

44 44

45 45 Case Study of Pollution Prevention for Printed Circuit Board

46 46 Case Study of Pollution Prevention for Printed Circuit Board

47 47 Case Study of Pollution Prevention for Printed Circuit Board zStep 12: Develop Material Balance for each processing area

48 48 Case Study of Pollution Prevention for Printed Circuit Board Electroplating Line (Microplate 9000 line)

49 49 Case Study of Pollution Prevention for Printed Circuit Board Oxide coating area

50 50 Case Study of Pollution Prevention for Printed Circuit Board

51 51 Case Study of Pollution Prevention for Printed Circuit Board zStep 13: Evaluating the Material Balance yMicro-etch rinse accounts for 90% of copper loading in sensitizing area yMicro-etch rinse accounts for 56% of total plant rinse water copper loading to treatment plant yOther major sources of contaminated rinse water are electroplating rinse, sulfuric acid/peroxide rinse and deburrer rinse

52 52 Case Study of Pollution Prevention for Printed Circuit Board zStep 14: Refining Material Balances zStep 15: Implementing Obvious Waste Reduction Measures ySand filter in deburring operation was backwashed with dirty water, leading to entrainment of copper fines throughout sand bed and release into filtered water yBag filter captures copper fines, but these are sent to landfill. At 2.6 kg/3 days and $0.9/kg, it means $275 per year

53 53 Case Study of Pollution Prevention for Printed Circuit Board zStep 15: Implementing Obvious Waste Reduction Measures yRecirculating pumps in copper electroplating line drip weak copper solution onto floor, which then goes to drains. Loading of about 70 g Cu/day yAlum added to wastewater in pit 1 not necessary for metal hydroxide precipitation (only useful for colloids). Increases sludge volume

54 54 Case Study of Pollution Prevention for Printed Circuit Board zStep 15: Implementing Obvious Waste Reduction Measures ySand filters installed after sedimentation tank were not reducing Cu in effluent (nor SS) yA 50% reduction in Cu loading from sensitizing micro-etch rinse through improved rinsing could result in a 40% reduction in rinse water loading to wastewater treatment plant, and lower Cu in outlet

55 55 Case Study of Pollution Prevention for Printed Circuit Board zStep 16: Treatability Tests zStep 17: Long-Term Waste Reduction Options yWastewater segregation and treatment yUpgrading pH adjustment, clarification, sand filtration systems yInstallation of static rinse tank in electroless copper plating bath to collect Cu electrolytically in a special treatment unit

56 56 Case Study of Pollution Prevention for Printed Circuit Board zStep 18: Economic Evaluation yCopper recovery: $3,500/yr yReduced sludge transportation and landfilling costs: $22,000/yr yProcess improvements & capital expenditures: $265,000/yr

57 57 Case Study of Pollution Prevention for Printed Circuit Board zStep 19: Other considerations yEffluent does not comply with NPDES permit yLegal action possible yTime spent by upper mgmt on wastewater issues zStep 20: Develop and Implement Action Plan


Download ppt "1 ESM 595 F Pollution Prevention in the Electronics Industry."

Similar presentations


Ads by Google