Keep in mind that not every PCB contains all the layers listed â the need for different layer types depends on the specifics of your design. Single layer boards typically include: a mechanical layer, a keep out layer, a routing layer, an overlay layer, a solder mask layer and a solder paste layer.
An austenitic (300 series) stainless steel will outlast both aluminum and steel exposed to rain or salt spray. Steel without a protective coating will do poorly in both environments but if properly plated or painted, may last a long time. The aluminum alloys likely to be found in many consumer products may develop âlawn chair diseaseâ exposed to at least urban rain and condensation but possibly also in cleaner environments as well (up to you to test).
Aluminum being the most abundant metal in the earthâs crust (at 8.2% of the total metals) is never found free in nature. Aluminum is reactive and will react spontaneously with water and/or air to form aluminum oxide.Aluminum oxide, Al2O3, forms a stable passive layer that protects aluminum from corrosion or further oxidation.This layer is about 4 nm thick and will provide corrosion protection as long as this oxide layer is stable. Aluminum is an amphoteric metal and can react with an acid as well as a base.The protective layer of aluminum oxide will deteriorate in environments with high or low pH or even in environments where aggressive ions are present.luminum is reactive and will react spontaneously with water and/or air to form aluminum oxide. Aluminum oxide, Al2O3, forms a stable passive layer that protects aluminum from corrosion or further oxidation.