Whodat? Whodunit? Mysteries with Measurement. Solving. Jim Raymont

Transcription

1 Whodunit? Solving Whodat? UV Curing Jim Raymont Mysteries with Measurement

2 Solving UV Mysteries Anything that you can measure, you have a better chance of controlling. Things that you do not measure become the cause of mysterious problems Larry Goldberg-Beta Industries UV Can Be Mysterious Unless You Understand It Cannot see it with the visible eye Wavelength is a nanometer (nm)-a billionth of a meter Reduce UV mysteries and process variables to increase profit Ask questions as we go Will share this presentation as PDF Here to help during the SGIA show (Booth 2800)

3 UV Curing-Crime Scene Producing a large amount of product before detecting a problem.

4 Round Up The Usual Suspects Suspect 1A: The Formulator Suspect 1B: The Equipment Supplier

5 Please Describe the.. Abrasion Resistance Scratch Resistance Chemical Resistance Hardness Weatherability Non-Yellowing Flexibility Tensile Strength Gloss Coating Viscosity Film Thickness Ability to Over Coat TBD TBD What properties are formulation driven? What properties are process/uv source driven?

6 The UV Process

7 The UV Process-Analogy Cake: Bake at 350 Ffor 30 minutes Oven Temperature ( F) is similar to Irradiance (Watts/cm 2 ) Bake Time (Minutes or seconds) is similar to Energy Density (Joules/cm 2 ) Not Specified: Oven Type Changing the Cake Process Window 350 X 30= 10,500 Equal Degree Minute Options 700 Ffor 15 minutes? 175 F for 60 minutes? What if the cake mix only gave you the time?

8 Speaking the Same Terminology Irradiance (Intensity) Expressed in watts or milliwatts per square centimeter (W/cm 2 or mw/cm 2 ) Total radiant power of (all) wavelengths passing from all incident directions onto an infinitesimally small area (cm 2 ) Depth of cure, penetration through pigments and opaque colors, adhesion to the substrate Energy Density (Dose) Expressed in Joules (J/cm 2 ) or millijoules (mj/cm 2 ) per square centimeter Incorporates time as part of the measurement One watt for One second = One Joule Area under the irradiance curve Often the only UV exposure guide number supplied

9 Speaking the Same Terminology Peak Irradiance Time Communication Process Development Transition to Production Production Within a company With Supply Chain

10 Speaking the Same Language Broadband UV Spectrum UVA: nm Black light, UV Inks, adhesion UVB: nm Toughness, skin response UVC: nm, germicidal (254 nm), surface cure, tack, chemical or scratch resistance UVV: nm, opaque/white, thick coats, adhesion, depth of cure Broadband Instrument Responses Instrument Bandwidths are not defined and vary from manufacturer to manufacturer and how they are specified EIT UVA nm, Full Width Half Max (FWHM), CWL 365 nm IL UVA nm CWL 365 nm EIT UVA nm IL UVA nm UV LEDs Discussed Later

11 Process Window I am loose and tight in all the wrong places

12 Process Window The range in which a process will work with the desired results Adhesion, hardness, flexibility, gloss, texture, stain or scratch resistance, chemical rub, cross hatch, abrasion rub, color ID, registration Often a compromise Invest before production & confirm when things are working! Starting guidelines from formulator? Define your lower limits and document the readings Increase line speed/decrease applied power until you undercure, note readings and cushion by 20% Upper limits? Monitor your readings by job, hour, shift or day as required to maintain quality Establish your process window during the design/development phase and start monitoring from day one in production

13 Process Window Starting Point: Formulator Guidelines Testing can define a process window Lab testing is less expensive than production testing or no process window Variables: Line speed Lamp distance Lamp output Bulb Type Source Type Coating

14 Process Window Normal Operating Window Caution 20% Undercure Buffer Range Stop!Undercure Limit Over cure or over temperature?

15 Gathering UV Evidence We can t ask a UV lamp or a power supply to confess, but we can gather evidence using other means

16 Gathering UV Evidence Did you perform the maintenance? Did You?

17 Gathering Evidence

18 Gathering UV Evidence Right Tools? Right Tests? Right Expectations? Documentation?

19 Gathering UV Evidence = Gather and preserve evidence to use it for when conditions change

20 Preserving UV Evidence For each UV lamp system Hour meter Indicated vs. actual process speed Power settings (WPI, Amps) Irradiance (W/cm 2 ) Radiant Energy Density(J/cm 2 ) Lamp matched to chemistry Focus/Reflector condition TBD Poor chain of custody Date Line Speed Dwell Time FPM/RPM UV System: North Line Lamp: 2 Ind. Actual. Power WPI Hour Meter Irradiance (W/cm 2 ) Energy Density (J/cm 2 ) 10/

21 Gathering UV Evidence Profiling Radiometers Profile helps determine focus of system and tracks changes Lamp types Break down multi-lamp systems Focused lamp UV W/cm 2 Non-Focused lamp Time in seconds Distance Change-Same lamp FOCUSED 858 mw/cm 2 UV W/cm 2 UV W/cm 2 NON-FOCUSED 290 mw/cm mj/cm 2 Dimensional Curing 1707 mj/cm 2 Gloss Control Time in seconds Time in seconds

22 Gathering UV Evidence Differences in: Irradiance values Lamp Types Focus of Lamps Speed collected A typical Irradiance Profile

23 Gathering UV Evidence In God we trust, all others bring data Dr. W. Edwards Deming

24 Gathering UV Evidence What Data (Evidence) Is Needed? Consistent Data Collection Techniques Fooled by the Equipment? Do not contaminate the crime scene or measurement tools

25 Gathering UV Evidence Ref Readings Unit Readings % Deviation Unit Power Puck II Power Puck II s/n Speed (f/m) 25 feet/min 25 feet/min UVA mj/cm2 mw/cm2 mj/cm2 mw/cm2 mj/cm2 mw/cm % -1.11% % +4.30% % -4.57% Average % -0.46% % STEDV 2.496% 2.001% 4.855% 2.537% 7.142% 4.488% Repeat for other UV bands

26 Analyzing the UV Evidence A Scandal in Bohemia

27 My Best Cases Inspector Jacques Clouseau: It's amazing how he fell perfectly into the chalk outline on the floor. Ponton: I think they drew the outline after he was shot. Inspector Jacques Clouseau: Ah! We must be working with some kind of mastermind!

28 Cases of Absent Minded Staff

29 Human Error Temperature Reading UV Readings Unit was sent through UV system upside down

30 Arc lamp performance-data 55 (140 cm) bulb Irradiance mw/cm 2 Data collected 3/24/16 Band Left Center Right Highest Delta UVA % UVB % UVC % UVV % Energy Density mj/cm 2 UVA % UVB % UVC % UVV % Bulb not installed correctly in UV system

31 Arc Lamp Performance-Graph Graphically display UV across width of bulb

32 Instrument Care Radiometers work better when properly maintained

33 Optics & Sensor Care Optics work better when properly maintained

34 UV Measurement Challenges Irradiance W/cm 2 Data Collected 3/24/16 Band Before After Difference UVA % UVB % UVC % UVV % Before: Data collected with contaminated optics After: Data collected after cleaning Energy Density J/cm 2 Band Before After Difference UVA % UVB % UVC % UVV %

35 UV Measurement Challenges Two recommended methods: o Lint/Detergent free wipes or IPA with cotton swab Advantages and disadvantages to each method First do no harm Avoid shirt sleeve, shop towel, etc. Avoid dry cleaning instrument

36 UV Measurement Challenges You Tube Video Link on EIT website

37 The Case of the Missing ID

38 How Old Are You? Hour Meter

39 Lamp Symptoms -Aging Devitrification / Clouding Mirroring Blackening / Erosion Contaminated Airflow

40 Aged Arc Lamp Middle End 440mW/cm 2 in the middle vs. 317 mw/cm 2 at the end How wide is your line compared to the product?

41 Variable: UV Energy Wavelength Mercury Gallium Iron Courtesy Heraeus Fusion UV

42 Variable: UV Energy Wavelength Ratio of different bands to identify bulb type

43 The Real World: Readings Profiling Radiometers Trouble shoot two identical production lines (Speed, bulb types) UVA Line 1 UVV Blue UVA Line Speed Changed UVV Bulb Type Changed Red UVV UVA Line 2

44 UV Sources: Spectral Output With 600 hours of run time would you change this bulb? OLD NEW UVA Energy Density: 537 to 487 mj/cm 2 UVA Irradiance: 309 to 290 mw/cm 2

45 UV Sources: Spectral Output Change Now? OLD NEW UVV Energy Density: 737 to 1331 mj/cm 2 UVV Irradiance: 397 to 734 mw/cm 2

46 The Case of the Misguided Purchasing Staff

47 Bulbs: Buy on Value vs. Price Intensity Hours Courtesy: Efsen Engineering

48 Bulbs: Buy on Value vs. Price Watch purchasing staff getting specials

49 The Case of the Missing Maintenance Team

50 Neglect of UV curing system

51 Mystery: Bad Reflectors Dirty, damaged and improper reflectors can be detected by their distinctive UV fingerprints on a profiling radiometer.

52 Process Variables-Reflectors A CLEAN BULB AND REFLECTOR DELIVERS ALL THE UV SPECTRUM IN THE RANGES OF UVA, UVB, UVC AND UVV A DIRTY BULB AND REFLECTOR DELIVERS VERY LITTLE OF THE UV SPECTRUM IN UVC & UVB, AND REDUCED AMOUNTS OF UVA AND UVV Abrasion Resistance Toughness Adhesion Adhesion & TiO 2 Cure A multi-channel radiometer allows you to compare short & long wave ratios and identify changes UVC: UVA UVC: UVV

53 The Case of the Overheated Lamp

54 Lamp Symptoms Inadequate Cooling The bowed lamp (left) overheated due to a damaged cooling system (right)

55 Diagnosing Inadequate Cooling/Airflow End Middle Sagging-15 % difference in irradiance levels middle to end

56 The Case of the Restless Operator

57 Mystery: Operator Error

58 Mystery: Operator Error Changing the distance from the UV System to the substrate FOCUSED 858 mw/cm 2 Non-focused is not always bad. Useful for gloss control for example 2096 mj/cm 2 NON-FOCUSED 290 mw/cm mj/cm 2 The effect of moving the UV housing away from the cure surface

59 Mystery: Operator Error Lamp Symptoms Distance to Part Varying the distance from the UV source to the substrate is a common source of process problems Substrate Height?

60 The Case of Unexpected Gremlins (Mr. Murphy)

61 Periodic vs. Real-Time UV Measurement Quantitative, routine maintenance Real-time status monitoring

62 Periodic vs. Real-Time UV Measurement Without an early warning system, the dipstick is useless.

63 When to Use? Works for applications where a radiometer will not fit or is not practical Web Bank of multiple lamps Lamps high off ground Continuous feedback about UV conditions Certificate of Conformance Tight Process Windows High Value Products Continuous monitoring of lamp intensity Communication Percentage readings Coordinate with absolute radiometer

64 Sensor Locations

65 Display/Conditioning Options Panel Mount One Sensor Display plus 0-10V Output Din Rail One Sensor, 0-10V Output Quartz Rod

66 Making a Case For New Lamp Sources

67 One Bullet Barney

68 Traditional UV Source Spectral Output 100 Hg spectra modified with added materials 90 Gallium 80 relative spectral radiance Mercury Iron wavelength [nm] Hg Ga Fe

69 EIT Bandwidth Responses

70 UV LEDs Wide variety of UV LED sources Multiple suppliers with wide level of expertise, support, finances Match source to your application & process Economics of source selected (ROI) Images courtesy Baldwin, Dymax, Integration Technology, Excelitas & Phoseon Technology

71 Adoption Curve

72 Adoption: Digital-Standard Suppliers: End Users: Courtesy

73 Adoption: Digital-Standard Courtesy

74 Adoption: Digital, Custom Suppliers: End Users: Courtesy

75 Adoption: Digital, Custom Courtesy

76 Adoption: Screen, simple Suppliers: End Users: Courtesy

77 Adoption: Screen, Industrial Suppliers: End Users: Courtesy

78 EIT Bandwidth Responses

79 Measurement of 395 nm LED Using UVA to measure a 385 nm or 395 nm LED Δ = 60% Δ = 95%

80 Evaluate LED Output Width of the LED at the 50% Power Point Variations between suppliers: Binning Longer wavelengths Sold as +/- 5 nm from center wavelength (CWL) 395 nm LED array output measured on a spectral radiometer at EIT

81 Define the right band? Theoretical Band Account for variation in the LED CWL L395 LED Output Spectra Showing + 5nm Spread of Cp Along with Required Filter Response to Obtain 2% Measurement

82 Optics Design

83 L395Instrument Response Total Measured Optical Response

84 LED-R Series LEDCure Radiometer L395 Total Optics Response Single Band, Cosine Response Two Options: Standard & Profiler 40 Watt Dynamic Range Suggested Operating Range L395 Start Threshold 400 mw/cm 2 to 40 W/cm mW/cm 2 Patented Optics Response

85 LEDCure L395 Performance Data collected at EIT February 9, 2017

86 LEDCure L395 Feedback A 395nm UV LED source was calibrated to 16W/cm² using the EIT L395. The UV LED source was then measured with another NIST traceable radiometer. The two radiometers matched to within 4% at different irradiance levels. Data Courtesy of Phoseon Technology

87 LEDCure L395 Feedback Energy Density (J/cm²) Energy Density Measurements EIT L395 Other NIST Meter Calculated The EIT measurement differed from the calculated value by less than 1%. The other NIST traceable radiometer differed from the calculated value by more than 13%. Data Courtesy of Phoseon Technology

88 LEDCure L395 Feedback Measurements at different irradiance settings were made with the EIT L395 radiometer, and compared to the expected values. The L395 s linearity across a 3:1 dynamic range is excellent. Data Courtesy of Phoseon Technology

89 LEDCure L395 Performance LEDCure vs. National Standard Working Distance (mm) Primary Standard: Integrating Sphere (W/cm 2 ) LEDCure L395 (W/cm 2 ) Difference % % % % % Data Courtesy Lumen Dynamics/Excelitas

90 UV LEDs Future Shorter wavelength LEDs Improvement in life & power in the shorter wavelengths Chemistry continues to improve to reach more applications Dual 365 & 395 nm Source Image courtesy Hamamatsu

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93 Crime Prevention Tips Establish a baseline. Establish a process window. Make measurements routinely. Measure consistently. Same location, speed, device Document test procedures Use right tools Label & mark equipment Calibrate all of your tools Communicate & Involve Supply Chain

94 Open Discussion-Questions Jim Raymont EIT Instrument Markets Director Sales Member ASDPT SGIA Booth 2800 Want a copy of this presentation? Send me an or give me a card