A helpful first step to remove enclosure moisture is to define the enclosure environment utilizing a temperature/humidity data logger. These inexpensive, battery-powered devices (~$200) record Electronic Dry Cabinets. Additionally they indicate the dew-point conditions in the enclosure (Fig. 6). Maintaining enclosure temperatures above dew-point temperatures is a requirement for condensation prevention.
Pursuing this option can be accomplished in a number of ways, starting from desiccant to thermoelectric dehumidifiers-the task is always to select an alternative which is inexpensive to both implement and sustain. This type of water-absorption capacity for desiccant is dependent on many different factors (e.g., desiccant type, humidity, temperature). As an example, silica gel can absorb as much as 40% of its weight in water. A 4’ x 6’ x 2’ electrical enclosure in a hot/humid environment would saturate 125 g of desiccant in approximately two air exchanges. Therefore, the resulting frequency of required desiccant change-outs (which affects maintenance costs) is basically driven by how well the enclosures are sealed. Unfortunately, with regards to desiccant regimes, each act of opening an enclosure to inspect the desiccant serves as an air exchange.
Dehumidifiers are relatively inexpensive, although finding convenient available power inside an enclosure may be problematic. The positive feature is the fact dehumidifiers remove the manual intervention connected with a desiccant regime. The negative feature of dehumidifiers is because they introduce yet another piece of equipment that can ultimately fail.
Another method is to minimize the chance of condensation through internal heaters (or light bulbs) to maintain the internal enclosure temperature well above dew-point temperatures. The downside is the fact higher temperatures may be detrimental for some heat-sensitive electronic components, and the higher temperature actually allows the air to hold more moisture. Venting and fans can help avoid condensation in certain situations-even though Dry Cabinets For PCB Storage still exists. One interesting product the makers of GORE-TEX® have produced involves screw-in vents which allow enclosures to breathe, while providing a barrier to moisture and contaminants. The theory behind this sort of venting is that it decreases the stress on door seals when there are pressure differentials between the enclosure as well as the environment. By equalizing pressure, the potential of moist air at higher pressure defeating your home seals is lessened.
Moisture-hardening of electronics includes many different techniques. With regards to connectors, using waterproof connectors or hardening existing connectors and splices with heat-shrink tubing can be useful to reduce water intrusion and corrosion. Avoiding horizontal orientation of components like printed circuit boards within the enclosure can minimize surfaces where condensation may collect for extended periods of time. Conformal coatings for lower-voltage printed circuit boards and the usage of potting (see Fig. 7) of higher-voltage components greatly increase the moisture resistance of components. Potting costs vary according to the dimensions of order, material selection jmmhra part geometry, but representative costs for very small orders (less than 10) typically fall inside the range of $18 to $45 per part. Yet another benefit from potting will be the added protection from shock and vibration.
Moisture protection of electronics is better approached by pursuing practices that maximize Moisture Control Cabinets during equipment installation, along with being prepared to mitigate failure through any one moisture-protection measure during operations. This plan, along with tracking equipment-maintenance performance to know how well moisture-protection measures are working, can lead to long-term minimization of electronics moisture-induced problems. MT.