Industry News|2022-02-22| admin
Due to the precision and rigor of FPC, each FPC workshop has high environmental hygiene requirements, and some workshops are even exposed to "yellow light" all day long. Humidity is also one of the indicators that needs to be strictly controlled. Today we will talk about the impact of humidity on FPCA?.
Humidity is an indicator that is very critical in the production process and must be strictly controlled. Low humidity can cause drying, ESD buildup, dust levels buildup, stencil openings are more likely to clog, and stencil wear is added. Practice has proved that low humidity will directly affect and reduce production capacity. Too high can cause the material to absorb moisture, resulting in delamination, popcorn effect, and solder balls. Moisture also reduces the TG value of the material and increases dynamic warpage during reflow soldering.
Almost all solid surfaces (such as metal, glass, ceramics, silicon, etc.) have a moist water-absorbing layer (monolayer or multi-layer), when the surface temperature is equal to the dew point temperature of the surrounding air (depending on temperature, humidity and air pressure) , this wet water-absorbing layer becomes the visible layer. The metal-to-metal friction increases as the humidity decreases, and at 20% RH and below, the friction is 1.5 times higher than that at 80% RH.
Porous or hygroscopic surfaces (epoxy, plastic, flux, etc.) tend to absorb these absorbent layers, and even when the surface temperature is lower than the dew point (condensation), there is no absorbent layer containing moisture visible on the surface of the material.
It is the water in these superficial monolayers that penetrates into the plastic encapsulated device (MSD), and when the monolayers approach 20 layers in thickness, the moisture absorbed by these monolayers will eventually cause damage during reflow soldering. Popcorn effect.
Humidity has many effects on production and production. In general, humidity is invisible (except for component addition), but the result is voids, voids, solder spatter, solder balls, and underfill voids.
In any process, the control of moisture and humidity is very important. The appearance of the body surface is abnormal, and the finished product is unqualified. Therefore, in the usual workshop, it is necessary to ensure that the moisture and humidity on the surface of the substrate are properly controlled to ensure that the environmental indicators in the production process of the finished product are within the specified scale.