Since 1987 the various market demand in Asia has grown and with it so has the number of suppliers. Today there are many companies throughout the world, no longer only in Asia, which provide desiccant dry cabinets.
Many of these cabinets were originally designed in Asia for the market at large in that humid part of the world, with both consumer and industrial applications in mind. Many until recently have only offered cabinets at higher MIN RH% level specifications than those demanded by electronics manufacturers; typically ~30% RH, partially due to their own technology limitations and/or various patent protections afforded other manufacturers. (Original patents have recently expired or are expiring shortly.) Some of these manufacturers however are now marketing their products specifically for the protection of MSD’s with the electronics industry.
As the understanding and wider acceptance of the proper care and handling of MSD’s within the PCB Assembly industry has grown, so has the demand for dry cabinets, and with that increased demand is an increased number of manufacturers promoting products capable of 5% RH and 10% RH levels.
Some of the cabinets are able to meet the much more stringent specifications required by PCB assemblers to satisfy IPC/JEDEC J-STD-033a (1-10% RH) more easily than others.
The graph (Fig. 1) below is an actual example of two cabinets from different manufacturers both with an operating specification of 1% RH. Measurements were taken 60 times per hour over a 24 hour period. The cabinets were ‘over loaded’ (Fig. 2); preventing adequate air circulation and aggravating the situation are the cardboard boxes which will easily retain any moisture introduced into the cabinets as they are accessed.