Why is there ink color difference between LED product modules without mask?
Jul 15, 2021
Factor 1 Plate grain
The texture of the plate also determines the color of the plate itself. The consistency is determined by the upstream manufacturers of PCB, which is basically uncontrollable and difficult to choose before PCB production.
Factor 2 The thickness of the ink
The coating uniformity of the ink determines the thickness of the ink. The thickness of the ink itself is in the micron level. A slight difference will lead to the difference in color.
Factor 3 Craft
Ink pre-treatment effect and post-treatment effect, pre-treatment including solder resistance exposure, exposure machine energy stability determines whether the effect of pre-treatment is good, and ink curing and other post-treatment process will also affect the color of ink.
Combine the above three reasons
Led to the differences in the PCB ink, and difficult to control in the aspect of improving of tin with thick ink thickness can lead to SMT process quantity increase, increases the risk of tin, but in front of the module production ink selection work, caused by large welding plate reflective area is very difficult to observe the difference of inky, automatic exposure machine must be used in processing production, Automatic exposure than semi-automatic exposure machine energy is more stable, to ensure the stability of exposure energy, requires the ink post-processing process using UV process, UV process will be better than baking process to ensure the consistency of ink color.
Finally, before and after the module production, the ink color identification and selection were carried out.
