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).
Galvanneal steel includes the process of galvanizing with an added step â after the zinc coating, the steel is heated to around 1050Â° Fahrenheit. This process of extreme heating draws more of the iron out of the steel and causes it to mix with the zinc. The finished product has an alloy coating of approximately 90% zinc and 10% iron. In the realm of steel doors and frames there are three types of galvanized and galvanneal steel used â A40, A60, and G90. The differences in the three are based on the percentage of galvanneal coating per square foot and the protection they offer.