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Explore the current UV curable range, UV40, and its performance and benefits compared to other materials. Find out how UV40 performs under thermal shock testing and learn about its physical properties and test methods.
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UV Product Range • Current UV Curable Range • UV40 - Background Released in 2006 UV curable acrylated polyurethane chemistry Allows fast throughput for high volume production
UV Product Range • Current UV Curable Range • UV40 - Range
UV Product Range • Current UV Curable Range • UV40 range – Markets
UV Product Range • Current UV Curable Range • UV40 – distribution of sales Percentage of UV40 Sales
UV Product Range Can be applied with all selective coaters Electrical, physical, mechanical properties designed for current industry demands – VOC free, Pb free, no clean • Performance and Benefits • Technical information - Properties
UV Product Range • Performance and Benefits • Technical information – Comparison to Silicones
UV Product Range • Performance and Benefits • Technical information – Comparison to Acrylics
UV Product Range • Performance and Benefits • Technical information – Comparison to Urethanes
UV Product Range Increased material costs but 100% solids material Better all round performance – has benefits of urethane and acrylate chemistry Flexibility through only bettered by silicones – lets explain… • Performance and Benefits • Explanation
UV Product Range • Tg (°C) – Glass Transition Temperature. • The temperature range at where it softens from a glassy to a rubbery polymer • CTE (ppm/°C) – Coefficient of Thermal Expansion • The dimensional response to a material upon changes in temperature • Performance and Benefits • Physical properties
UV Product Range DMA Method - dynamic applies small deformation to a sample in a cyclic manner allowing the materials response to stress, temperature, frequency and other values to be determined. TMA Method - thermal Applies constant static force to a material and reports the material change as temperature or time varies to record dimensional changes. DSC Method Differential thermal analysis is the measurement of the difference in temperature between a sample and a reference as heat is applied to the system. • Performance and Benefits • Test methods
UV Product Range • Performance and Benefits • DMA trace example
UV Product Range Silicones typically have a Tg higher than RT – flexible at RT and increased operating conditions UV40 range Tg around RT (depending on test method) - will be glass-like at lower temperatures So during thermal shock cycles UV40 spends longer ‘glass like’ per cycle than silicone based • Performance and Benefits • Test methods
UV Product Range Thermal cycle = like Mil spec – slow ramp between temperature extremes. 100 cycles • Performance and Benefits • Thermal shock or thermal cycle?
UV Product Range Thermal shock = automotive specifications – fast ramp (40-60C/min) designed to ‘shock’ materials / solder joints FORDspec -45 to +85C 1000cycles Also depends on CTE mismatch between components (metals, plastics etc) and coating – test board also important • Performance and Benefits • Thermal shock or thermal cycle?
UV Product Range Cracking has been observed with UV40-250 through thermal shock testing during customer qualifications Humiseal set up a in-house study to investigate the causes of cracking and mitigation strategies • Performance and Benefits • Material cracking through thermal shock
UV Product Range • Performance and Benefits • Test board
UV Product Range • Selectively apply UV40 and UV40-250 to the test board and run thermal shock tests to investigate: • Thickness • Secondary curing - Rapid cooling of assemblies after oven curing • UV dosage • Inspect at 20-40x magnification at intervals during thermal shock • Performance and Benefits • Design of Experiment
UV Product Range • Thermal shock info: -65C to +125C, 30 minute soak @ each temperature, 5 minute transition between T1 and T2. (~40°C/min Rate of Change) • →Inspect at 20-40x magnification at intervals in the thermal shock • Performance and Benefits • Design of Experiment
UV Product Range • Performance and Benefits • Findings after 500cycles *UV40 and UV40-250 at 100µm
UV Product Range During cure processes chemical bonds shorten in length →This causes shrinkage in coatings On flat substrate not an issue because coating unrestrained When applied over 3D components it creates stresses within coating as it cures Stress has to be relieved Can cause cracking Measured shrinkage of UV40 and UV40-250 at various cure conditions UV40-250 shrinks more than UV40 Higher stress within coating Increased tendency to crack • Performance and Benefits • Explanation
UV Product Range Control Coating Thickness Avoid Accelerated Secondary Cure Process Proper UV Cure Conditions Thermal Shock Conditions Higher rate of temp change increased tendency for cracks UV40 vs. UV40-250 Less shrinkage during cure Lower incidence of cracking Tg = 45 vs 25C • Performance and Benefits • Mitigation
UV Product Range • Based on UV40 chemistry which has many excellent properties • New UV curable will have increased crack resistance – • increased flexibility, • raise the Tg • match CTE closer to components • Formulation and testing is under way – expected earliest release date late 2012 • Performance and Benefits • Next steps – UV40 new
HumiSeal • 295 University Avenue •Westwood • MA 02090 • USA Tel: +1 781 8332 HumiSeal Europe • 505 Eskdale Road • Winnersh Wokingham • Berkshire • RG41 5TU • United Kingdom Tel: +44 (0)1189 442 333 www.humiseal.com