Why it is Necessary to Control Humidity in PCB Assemblies
A Printed circuit board is quite literally an insulated board on which wire is laid to create a circuit. They are a critical and very necessary part of all electronic products. They are in everything from complex computers to basic smartphones. Since they are the base for the circuits that transfer electricity, if they were not included in an average electric machine that machine would just not work not to mention the fact that there would be no place to put the components. The market for PCBs is currently at $60 Billion, that’s Billion with a “B” and growing.
Just like any other electronics, require careful conditions during production to ensure that the integrity of the board is maintained before shipping. In general, things like dust, heat, and the focus of this article, humidity, will have an effect on the PCB.
Also Read: Printed Circuit Board (PCB) Assembly
Just like dust can interfere with and even interrupt circuits, and heat can cause some metal within the circuits to melt, humidity, meaning the amount of moisture in the air, can allow current to run through unwanted areas of the circuit board, causing extreme damage to the board and the circuits on it. Although that should be enough to prove that control over humidity, there are additional factors that could be hazardous to the board, and, by extension, the equipment that it is a part of. Imagine if an expensive new desktop computer fell apart, or in a more extreme example, a computer-guided car or airplane failed mid-transit.
Too much moisture in the board can cause numerous problems from delamination to solderability issues. It is a very simple fact that moisture is not good for any electronic component and this is especially true when it comes to PCBs. Reality is that PCBs are extremely absorbent so both the builder and the end user must use extreme caution when avoiding moisture.
If you are an end user in a high humidity state such as Florida it is highly recommended that you pre-bake the boards before you solder them. Yes, the fabricator will have packed them with desiccant packs to keep the moisture down. But even the short time that the boards are exposed to humidity before they are put into the assembly process can be enough for that board to absorb too much moisture.
The most recommended way of keeping your products safe is to keep a humidity level at around %50, or between %40-%60, which will let the PCBs stay dry while not drying out completely or causing static discharge, which can occur below this level of humidity: a normal amount of moisture in the air only will not affect them.
Remember moisture is our enemy. But baking the moisture out the boards prior to the assembly process is the simplest and most cost-effective way to keep your boards safe and dry.