Since PCBAs can sometimes be sensitive to environmental situations, you will mostly find them with a protective barrier. That’s where the injection mold process comes in. It is a good way of protecting PCBAs and ensuring aesthetic appeal. Today, we will have a clear picture of PCB overmold.
What is a Printed Circuit Board (PCB)?
PCBs are the small components enabling different kinds of modern technology to work. In past years, you connected the wires from one to another, which was a fairly tedious task in terms of maintenance and production. As a result, the concept of printing circuits on top of a board came about.
The whole process starts with a simple conductive sheet. A double insulation layer offers support for the conductive piece in most cases. Sheets undergo a drilling process to create registration holes needed for proper alignment. For CAD designs, you can use detailed 3D models to ensure everything is in place.
An alkaline solution used for etching helps to produce the desired tracing outline of copper. It works because UV lights position the mask on the copper layer, which is also a process you can do in bulk. Check any traces of copper for quality using an optical testing machine that looks out for short circuits and different kinds of damage. The green color characteristic of a solder mask coating offers protection and insulation. There is also a silkscreen that produces symbols, markings, or logos directly to the PCB. After the process, you can have the components soldered atop the PCB. After which, you can use the flying probe test to determine connectivity.
In most cases, PCBs use either burrowed technology or, more recently, surface mount technology based on the needs of a specific project.
Caption: Optical Testing Machine
What is Overmolding?
The term overmolding refers to a process that utilizes insert or injection molding to arrange and protect the component.
The first way of doing this is to have the PCBA assembly in place and inject the overmold directly over it. This method usually means more options for creating a streamlined appearance, customization of colors and logos, and the general overmold design.
The second way to do the overmold injection is to offer a more protective barrier for the PCBA. That means encapsulating it with something known as the Lexan encapsulation, which is a cap. The cap’s design also allows it to house the PCB and ensure it has a protective shell for any vulnerable components. After you make the cap, the next step is overmolding using the same options associated with the immediate over-molding process.
Benefits of Employing Molding and Overmolding with PCBs
Nonetheless, there is the cost aspect that you will have to consider when adding another level of protection. So, the question becomes, is it worth the investment? Anyone who raises the firmness of a PCB component with overmolding will get a better-performing and more durable system than someone who does not.
Additional flexural strength means high-traffic sections like cable exits can withstand more wear and tear and continue functioning properly.
Overmolding offers wall shielding around components. As a result, you will find that extreme environmental conditions such as high temperatures, water, impacts, abrasions, and other external forces do not damage them.
Overmolding provides an extra layer of shielding against even the most deliberate outside forces. It acts as your PCB’s direct protection element.
Overmolding helps to enhance the pull-strength and strain-relief capabilities of PCBs.
Overmolding helps seal off components from caustic elements like saltwater or oil.
The fact is that aesthetically looking components tend to sell more. With overmolding, PCBs tend to look better and are easier to maintain and integrate.
The process of customizing PCBs with an overmold has several benefits:
- It allows one to create different colors for an ideal overall wire management setup.
- It facilitates the good printing of corporate names, logos, or other branded messaging.
- It offers different points that allow for integrating attached hardware components like a flange.
- Provides varying exit point angles like a right angle, sometimes needed to cater to a project’s needs.
- It enables the use of different overmolding materials like thermoplastics or PVCs.
- Customization of overmolds involves employing different kinds of machines, such as the LPMS (Low-Pressure Molding System), to offer the most cost-efficient solution.
A Closer Look at the Process for Overmolding
The process can be very simple or extremely complicated. However, the most important thing is choosing the machine and the material.
Which Molding Machine to Use?
Injection molding machines are the driving force behind the overmolding cable engineering methodology. They can reach high or low levels of pressure to push whatever kind of molten material is based on the type of mold needed.
When picking the molding machine, tonnage refers to the force required to suspend molten resin within the mold. The bigger mold, the more needed. Having the correct injection molding machine is vital for the process.
Determining Which Materials Are Best For Overmolding
There is almost an endless amount of materials that one can use to produce varying final results. One may offer ideal rigidity, while another may result in more flexibility. The bottom line is that it all depends on the needs of a particular project.
Nonetheless, two of the most used overmold materials are PVC and TPU (thermoplastic polyurethane). The former is common mainly because of its economic features and is great for moisture-proofing and adding strength.
The Final Process of Injection Molding
After choosing the material, the next step will be to fill the hopper found on the injection molding machine and have the injection screw pump it into the mold. The process will cause the barrel to heat the materials and force them into the tooled mold. That will continue to add pressure up to the point where solidification can occur.
Caption: Molding Machine
When working with physically vulnerable components such as PCBs, it is good to have the proper training and skill set needed for such a task. Failure to do so can lead to sub-standard products or even a breakdown of the molding machine. For the best PCB services, contact wellpcb Tech, and our team of highly skilled professionals will get back to you.