Excessive temperature rise in reflow soldering will cause uneven wetting, which will inevitably cause the device to shift during the wetting imbalance process. Excessive wind cycles can also cause device displacement. Try to choose a reflow soldering machine with a temperature of 12 or more. Chain speed, temperature rise, circulating wind, etc. are strictly controlled items, that is, to meet the reliability requirements of welding cost, and to reduce or avoid the displacement components of LED, try to control to within the required range. Generally, the 2% range of the pixel pitch is used as the control value.
Please read the originial post here: http://ledscreenparts.suomiblog.com/evaluation-of-micro-pitch-led-show-technology-10037226