Tin whisker growth phenomenon, which can lead to short circuits in the electronic components and boards, becomes more critical in lead-free electronics. One potential solution is to use a conformal coating to mitigate the tin whisker growth.
In this study, a polyurethane acrylate (PUA) coating under the dual curing system (UV and moisture) was investigated in terms of chemical structure evolution and mechanical properties.
Exploring UV/moisture curing effects
Both the UV curing portion (10, 20, 30 and 40 min) and moisture curing portion (2, 3, 4 and 5 h) were evaluated. Infrared and Raman spectroscopy, differential scanning calorimetry and thermogravimetric analysis were used to examine the curing status and microphase separation of the coating. In addition, the influence of strain rate in tensile test on the mechanical behaviour of the film was studied.
Optimum properties by partial curing
The tensile test results show that partial cured film (UV 20 min and moisture 4 h) has optimum mechanical performance from the strength and ductility point of view. The fully cured film (UV 40 min and moisture 4 h), however, possesses more strength to resist plastic deformation during a long-term loading.
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