Dust Level Control in Phototooling Basics Eric Janssens January 2002

1. Dust Level Controlin PhototoolingBasicsEric Janssens January 2002

2. What is dust ? • Any material particles • that may have a negative effect on their environment

3. Sources of dust • Natural dust • Cosmic dust from outer space • Eruption of volcano’s • Sand, stone ... due to erosion by wind and water • Seeds, pollen • Humans • Man generated dust • Exhaust by industry and traffic • Generated by any friction • Human body tissue: hair, skin particle, sweat, ….

4. Dust generated by the human body • Calling generates 20,000 particles • Coughing generates 600,000 particles • Sneezing generates 1,200,000 particles • A man looses 1 hair every 15 minutes • A man looses 15 grams of skin tissue every day

5. Dust generated by peoples action • Writing on paper 30µm particles • Folding paper 60µm particles • Rubbing on a painted surface 90µm particles • Rubbing metal on metal 100µm particles • Putting on a screw 100µm particles • ….. By moving man make dust particles air born

6. Dust particles - Size distribution • Air born dust particles range in size from 0 to +/- 50 m • There are many small particles and fewer larger ones • Remark: dust particles may conglomerate

7. Dust particles - Size distribution

8. Definition Clean Room Class • Clean room class x means: • one cubic feet of air contains x particles of 0,5 m or smaller

10. The importance of clean room conditions • As long as dust particles are relative small compared to the lines and spaces they don’t cause much trouble • Stricter demands for PCB fabrication • Ever decreasing line and space widths • Stricter tolerances for lines and spaces and pads • More layers • Higher yield • Today the size of an average dust particles is ¼ to ½ of an average L/S • Today dust particles cause more defects • and the defects are more expensive

11. Dust particles in PCB production • Dust particles jeopardise image formation: • Phototool generation • Dust on the film while plotting • Dust in the light path while plotting • Dust on the plotter drum (fly off,out focus) • Dust on the film while processing • Primary imaging • Secondary imaging • Dust particles scratch phototools and resist

12. Dust measurement • Measuring/counting tools • Particle size Measuring device • 2 - 100 µm Filter • > 20 µm Petri dish

13. Petri dish

14. Pert dish

15. Pert dish

16. Dust measurement • Measuring/counting tools • Particle size Measuring device • 2 - 100 µm Filter • > 20 µm Petri dish • 0.5 - 30 µm Particle counters with light* • 0.1 - 5 µm Particle counter with laser light* • * does not measure the heavier dust particles • Remark • The naked human eye can see: • 50 µm particles under normal conditions • 25 µm particles under ideal conditions

17. Dust measurement: take care • We are fighting an invisible enemy

18. PCB production anno 2000 • To remain competitive in the PCB industry • production is to be done in clean room conditions • where the dust level is well controlled

19. Clean room: the compromise • A clean room has to be • build correctly • and • used correctly • Find a compromise • Quality of the installation versus installation cost • Discipline applied versus comfort

20. Clean room: how to organise • No paper or card board (paper is compressed dust) • Limit access of people • Limit access of materials • Avoid transportation from one compartment to another (install hatch) • No cutting or punching of film in the clean room • No knifes,no scissors, nail files, no pencils • No posters, no photos, no radio • Use clean room certified tools and equipment • discipline discipline discipline discipline discipline discipline discipline

21. Clean room: how to act • No paper or card board (paper is compressed dust) • Clean feet • Dress correctly (overall, hair cap, over shoes, gloves) • Never ever enter in “out side” clothing, not even for just a second • Never ever leave the clean room in clean room clothing • No brief cases, no handbags • No food, no drinks, no smoking • Move slowly and as little as possible • Keep films in vertical position, use (humidity tide) envelopes • Clean the film as often as needed • discipline discipline discipline discipline discipline discipline discipline

22. Clean room: maintain dust level • Golden rule • Prevent dust generation (people, production process, environment) • Prevent dust from entering the clean room • Remove dust

23. Clean room: maintain dust level • Implement cleaning programme • per batch, shift, day, week, month • what to clean, how to clean • Remark: after cleaning the dust level is higher as before • vacuum cleaner out of the clean room • Replace mats • Replace filters • Wash clean room clothing in special washing machine • discipline discipline discipline discipline discipline discipline discipline

24. Clean room: SPC programme • Dust level at all relevant locations • Cleaning • Pressure over the filters • Air flows • .… • discipline discipline discipline discipline discipline discipline discipline

25. Shoeshine Changing room + OverallsHaircapGlovers Over shoes Hatch Hatch   Lock   ++ Dust retainingmat Filmstock Package Check +++ +++ RetouchLabelMeasure Plotter Copy onto diazo Processor Laminate +++++ Climitisefilm ++++ Chemistry supply The ideal phototool lab

26. Dust level control at Agfa • Agfa’s commitment • Production in class 1,000 • Cutting and packaging in class 5,000 • Special PCB packaging • Film safe

27. Dust level control at Agfa

28. Dust level control at Agfa

29. Dust level control at Agfa

30. Dust level control at Agfa

31. Dust level control at Agfa

32. PCB packaging

33. Film safe • 790 mm x 680 mm: FROJN • 1179 mm x 870 mm: FROFG • 1690 mm x 1480 mm: FPMM3

34. Conclusion • Working in clean room conditions • is • producing with well-focused discipline • in a well-monitored environment • in order to control defects

35. Conclusion • Dust level control in the PCB industry is a question of common sense and discipline! but it makes the difference between making or loosing money