A helpful first step to eliminate enclosure moisture is to characterize the enclosure environment using a temperature/humidity data logger. These low-cost, battery-powered devices (~$200) record Electronic Dry Cabinets. In addition 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 choice can be accomplished in a quantity of ways, which range from desiccant to thermoelectric dehumidifiers-the challenge is to select an option that is inexpensive to both implement and sustain. This type of water-absorption capability of desiccant is influenced by many different factors (e.g., desiccant type, humidity, temperature). For instance, silica gel can absorb approximately 40% of their weight in water. A 4’ x 6’ x 2’ electrical enclosure in a hot/humid environment would saturate 125 g of desiccant within two air exchanges. Therefore, the resulting frequency of required desiccant change-outs (which affects maintenance costs) is essentially driven by how well the enclosures are sealed. Unfortunately, in terms of desiccant regimes, each act of opening an enclosure to inspect the desiccant functions as an air exchange.
Dehumidifiers are comparatively cheap, although finding convenient available power inside an enclosure may be problematic. The positive feature is the fact that dehumidifiers remove the manual intervention associated with a desiccant regime. The negative feature of dehumidifiers is they introduce one more device that can ultimately fail.
Another method is to minimize the opportunity of condensation through internal heaters (or light bulbs) to help keep the inner enclosure temperature well above dew-point temperatures. The down-side is the fact higher temperatures may be detrimental to a few heat-sensitive electronic components, and also 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 that enable enclosures to breathe, while providing a barrier to moisture and contaminants. The idea behind this type of venting is it decreases the stress on door seals when you will find pressure differentials involving the enclosure and also the environment. By equalizing pressure, the potential of moist air at higher pressure defeating your home seals is lessened.
Moisture-hardening of electronics includes a variety of techniques. In terms of connectors, using waterproof connectors or hardening existing connectors and splices with heat-shrink tubing can come in handy to minimize water intrusion and corrosion. Avoiding horizontal orientation of components like printed circuit boards within the enclosure can minimize surfaces where condensation may collect for prolonged amounts of time. Conformal coatings for lower-voltage printed circuit boards and using potting (see Fig. 7) of higher-voltage components greatly raise the moisture resistance of components. Potting costs vary based on the size of order, material selection jmmhra part geometry, but representative costs for very small orders (less than 10) typically fall in the range of $18 to $45 per part. An additional advantage of potting is the added protection from shock and vibration.
Moisture protection of electronics is best approached by pursuing practices that maximize Dehumidifying Dry Cabinets during equipment installation, in conjunction with being ready to mitigate failure through any one moisture-protection measure during operations. This tactic, together 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.