Solder paste release from the stencil is a critical factor in print quality, and ultimately, overall electronic product quality and reliability. To better understand release mechanics, an experiment was devised using a video microscope to capture the separation of the stencil from the PCB.
The experiment incorporates different aperture area ratios, solder pastes, stencil nanocoatings and underwipe solvents to visualize their effects on paste release. This study builds on previous research that developed the test setup and recording methods, and incorporates some modifications to the original experimental configuration to improve image quality.
The outputs of the experiments are videos that demonstrate the effects of solder paste formulation, solvent under wiping and nanocoating on paste release at different area ratios. The paper will discuss the observations from the videos, and the presentation will play the videos.
Nice experiments and anyone that knows me I love to use video as its so revealing in process development. The first work like this was conducted by one well know supplier of paste and printer technology and was very hush hush. NPL in the UK also included some paste release work with video from the underside of the stencil. Looking at paste fill then release from the stencil aperture side walls on glass with solder mask to show the impact of mask height is very revealing, it makes staff really understand what is happening then relate it to SPI measurement in production. Solder mask thickness variation particularity with thick copper is interesting too
Why IPA? because!
That is the standard reply to most process related questions.
We've always done it this way is another variation.