A is not visible to the naked eye, but distributed in the water vapor droplets around us can cause much damage to the LED bead? You might feel scare, but the fact tells us, many LED display of the accident is caused by the tiny water droplets.
A small water droplets to how much of a LED products?
Water in the atmosphere by diffusion penetration to the LED lamp bead encapsulation material inside. When the SMD LED device after patch loaded on the PCB, to flow to reflow furnace for reflow soldering. In the recirculation region and the whole device to around 183 degrees more than 30-90 - s, the highest temperature may be in 210-235 degrees (SnPb eutectic), peak of lead-free soldering will be higher, at about 245 degrees. In the reflow zone under the action of high temperature, the rapid expansion of LED device internal moisture will, devices with different material will lose adjustment, all kinds of connection will be adverse change, leading to the LED device stripping layering or blowout, and electrical properties of the device is affected or destruction.
Severe damage, exterior deformation, cracks, etc., in most cases, the naked eye look not to come out. But with the passage of time, cracks will crack, the greater the adverse to finally form circuit.
A small water droplets to how much of a LED products? (diagram)

Stripping phenomenon amplifier schematic diagram

In order to detect assembly house manufacturing of LED lights, have enough ability to resist humidity, avoid the above
In order to detect assembly house manufacturing of LED lights, have enough ability to resist humidity, avoid even the appearance of the wire stripping, the IPC/JEDEC defines a set of standard "humidity sensitive level" as follows, people in need can also to JEDEC's official website to download J - STD - 020 - d. 1.
The file to determine the sealing solid-state surface mount devices (SMD) water lead to stress sensitive level of classification, used to determine the initial reliability appraisal classification level should be adopted. Once the classification level, SMD components in the process of packaging, storage, processing may take appropriate measures, and in the assembly welding in the process of reflow attachment and/or repair operations to avoid thermal and mechanical damage.

"The level of humidity sensitive" MSL (Moisture Sentivity levels), from small to large, the smaller the number of the better said its ability to resist humidity; The greater the number, said its environment can be exposed to moisture to the shorter time.
According to the standard of MSL, display factory and engineering business is easy to pick up a qualified lamp bead, and for the LED lamp bead in the subsequent process of packaging, storage, processing with clear rules. Due to the standard for the LED lamp bead quality request is higher, dare to use packaging companies also very little, have a career abroad and daily, domestic has makar, lehman, blue.
To level 3 (level 3) to illustrate, if parts are exposed to the Celsius temperature of 30 ° C and 60% humidity environment, then the storage time can't more than 192 hours (including LED assembly house to deduct the 24 hours of exposure time, so the LED display factory is only 168 hours (= 192-24) of workshop), which means for level 3 leds components from the vacuum packing, it must be in 168 hours playing and after Reflow Reflow soldering. If not within the prescribed period of time after Reflow, must want to vacuum packaging, packaging, again after it is best to bake because after baking time can zero recalculation. If in excess of the prescribed time, it must to use to bake.
Destroy an LED display screen doesn't need strong wind storm, a small water droplets chamberlain said.