Vaccum matalization has been around for years. It's not really a new process,truth be known. Back in the days when computers were first made, this process was incorporated to "shield" electronic componantry.
Basically what happens is this.....
A protective "cup" if you will is formed around a plastic mold to make a case for printed circuit boards and save them from electromagnetic interferance (EMI) from surrounding structures. Think of it this way... you have a REALLY old car and you hear this constant "buzz" from the ignition coil and wires controlling spark through your AM radio all the time when you accelerate. What you do is get a noise supression wire to help cut down on that effect therefore, creating your own EMI resistor. Vacuum metalization enclosures are no different. You take a sensative piece of electronic equipment and enclose it so that it doesn't have any interferance from a surrounding electronic structure. Say maybe such as a vacuum tube (like in the olden days) or a microprocessor (like those used in your very own television set). No doubt you have seen these such vacuum formed metals before but just didn't know what they are.
Now... with that said, the reason that you see them being clear powder coated is for insulation properties,no doubt. If the metal form has not been completed yet by means of installing the printed circuit board (PCB) yet.... it will withstand the heat of the application. Of course... if the PCB is in need of the EMI resistance... there are many companies out there that make a wet-spray application for this function as well. I've used a humiseal product with great success over the years as well as parylene deposition with the same if not better effect. All in all.... it's just a coating that insulates, comprised of a polymer structure. Liquid, monomer deposition, electrostatic powder coating... it all reaches the same result in the end. A metal box that houses electronic equipment coated with a non-conductive coating. Another good example is a turn signal relay found in pre-mid 80's automobiles. Nowadays they make them out of plastic.... but if you go to the junkyard, you'll see them. Funny little metal squares that plug into a block or cluster of some sort. THOSE are also vacuum formed metals or a derivative of it (stamped castings).
The process is this : A mold or "negative" is made of the part you want to surround. Resin capable of withstanding heat and pressure is made from that mold creating a "positive" of the original structure. It is then placed in a chamber and thin metal is sucked over the top of it. The vacuumed metal now leaves another negative of the cast and is removed and trimmed of any excess. THIS is your vacuum formed metal. You have a choice of either coating it now ( the ad in which sparked this post) or putting your PCB in the metal and leaving it be or coating it later if you wish. Hope that explains the process and what it is exactly..... Russ
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