A detailed guideline for PCB mount
PCB, which is an acronym for Printed Circuit Board, is the backbone of every electronic device built nowadays. These boards can vary in size, shape, and assembly concerning their desired application.
There come many phases in making the PCBs, and one of those crucial phases is the installation. When talking about PCB installation, the term PCB mount comes in handy. This term is often confused with other PCB-related terminologies. But you don’t need to be confused anymore, because in this article all of your ifs and buts related to PCB mount will be rectified.
What does PCB mount mean?
In general, a PCB mount is a specific opening in a PCB made for fitment. This fitment can be either of the PCB board on an enclosure or a soldering point for a switch on the board to attach a plate. Both of these types of mounts can be located on PCBs designed for computer keyboards, calculators, etc. The footprint of the mount can vary with its application.
What is a mounting hole PCB?
Attachment mounts available on a PCB that allow the board to get coupled with a surface are known as mounting holes. This is one of the main applications of PCB mount.
The main purpose served by these mounting holes is that they offer a more convenient placement of PCBs within a system. Its common use can be observed in the boards fitted in laptops and mobile phones. These holes can vary in both number and size depending on the application.
What size are PCB mounting holes?
Generally, the sizes of the mounting holes are confused with the sizes of the pads, for through-hole components. The sizes of PCB mounting holes can vary with a lot of factors like the application of the board, the system it is going to be mounted to, available mounting spaces in the system, the type of PCB mount footprint being used, or the type of fasteners being used.
But mostly the sizes of the PCB mounting holes vary from 0.75mm to 11mm. These sizes are standardized due to the standard sizes of fasteners and screws.
How do you add mount holes to PCB?
Adding mount holes to the PCB is simple but it can be confusing for many. But this simplicity comes with a caution that, you need to add the PCB mount footprint during the designing of the board. This footprint will be a “mounting hole” object in the designer’s tool.
That mounting hole object will allow you to select the size of the hole and its depth. In this way, when the PCB gets fabricated, the hole can be easily drilled. If you somehow have missed placing the footprint of the holes during the design, then what you can do is find a reasonable spot on the board and drill it out manually.
How to design PCB mounting holes？
Most people get confused while using the PCB mount footprints for the mounting holes. Most of their concerns tangle around the fact of where to place them and how to use the footprint. The purpose of these mounting holes decides their placement in the system.
Apart from just holding the board in place, these PCB mounts are also used as conductive ground, with plating and radial-via’s, for the PCB. So, considering this fact the size and location are specified.
Mostly they are placed at the corners of the board as it provides the designer more convenience, and in the case of grounded mounts, it provides them eloquent space. But one thing to keep in mind is that the mounts should be placed in a manner so that they keep the board, electrically and mechanically, balanced at all times.
Should mounting holes be plated?
Before getting into the detail of whether to plate the mounting holes or not, first, you should know why the PCB mounts are plated. Mounting holes are plated in those PCBs whose PCB mounts are offering a conductive ground.
Plating the holes provides better conduction between the upper and lower pads. So, in the case of grounded mounts the holes should be plated, but only platting the holes won’t be enough because when the fasteners are passed through the holes, they will damage the plate. So alongside plating, radial vias should also be fabricated around the mounts so that the conduction can persist even if the plate gets damaged.
Meanwhile, if the mounting holes don’t have any grounding functionality, there is no need to plate the mounting holes. But in some cases, the plating can also provide better support and protection to the PCB.
How do you mount a PCB plate?
Usually, plates are mounted on the PCBs to keep them enclosed. But mounting the plates is a bit of daunting task because there are some prerequisites for them. First, there should be PCB mounts available on the board and they should align with openings in the plates.
Afterward, the switches can be placed on the mounts, on the PCB, from where those switches can be attached to the plate. While mounting the plate keep in mind that the switches should be flexible enough to support the plate and prevent applying excessive pressure on the PCB.
How do you screw into PCB?
Adding fasteners, like screws and clips, to the mounting holes of a PCB requires some tricks to get it all right. First, you should find the right size and type of screw that you’ll be using to couple the PCB. The size of the screw should be smaller in diameter than that of the hole because if the screw is of the same size as that of the hole it’ll damage the board during installation.
If the PCB mount has conductive fabrication for grounding, then the screw used should be of stainless steel to serve the purpose. But if the only purpose of PCB mounts is the fitment of the board, then plastic screws can be more convenient. While screwing, try to be gentle and not apply too much pressure on the board, as it can damage the PCB.