Conditions at work can be rough…
The printed circuit board in the photograph here came from an industrial label printer, one used to create labels for our product packages. The printer refused to print for no apparent reason, and despite numerous attempts to update or replace printer drivers, using a different computer, and other fiddling it remained stubbornly inoperative.
So we bought a replacemnt and continued shipping product.
The printer sat in my office for a bit, and one quiet afternoon I decided to do a little forensic disassembly, and scrap any useful bits before I tossed the remaing carcass.
The reason for failure was apparent fairly quickly, the circuit board was subject to substantial corrosion. Particularly the vias, those little holes where the circuits jump from one layer of the PCB to the other. On this board the vias were not tented, not covered in the green solder mask that may have protected the vulnerable copper.
Even the low voltages present on the circuits will hasten deterioration through galvanic corrosion, the voltage accelerating the destruction of the copper by driving the corrosion.
The conditions at work are deadly to electronics, sitting only 100 yards from the surf the very air is saturated with salt, particularly on days with heavy surf when the salt mist wafts in from the crashing waves and hangs as a haze in the air. This printer was used on an open bay, a roof overhead and a couple walls, but otherwise open for the salt mist to float through.
I knew this could happen, but to see it so vividly demonstrated is educational. There are lessons here for electrical engineers like myself.
Some precautions I had already been taking. The many circuit board assemblies of my own design that have been deployed around the facility are enclosed in sealed enclosures with gaskets and cable glands. In addition the PCB’s have been conformal coated, a protective coating painted across the boards after passing first checkout and before installation.
These precautions will slow the decay due to environmental conditions, but things will eventually fail.
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