Chip Scale Package and Flip Chip Assembly Using Tacky Flux

摘要

For PCs and SR-defmed footprints with local SR-defined fiducials the following can be concluded: 1. There is a strong relationship between bump diameter, minimium SR-aperture and SR height. All parameters play an important role in the maximum placement accuracy; 2. From the results of the performed experiments can be concluded that an allowed offset of 20% from the solder resist aperture is a safe value for the cases the solder resist aperture ≥ 85% of the bump diameter. The solder resist height, in this cases, on the Cu-pad is ≤10μm; 3. If the SR-defmed fiducials is shifted the SR-defined footprint is also shifted over the same distance. The allowed offset stays the same for a shifted and not shifted solder resist layer; 4. For the tested combination, SR aperture = 70% of the bump diameter, some bumps rested on the solder resist layer and did not touch the Cu. During reflow these bumps do not solder.