The role of PCB is to withstand the extreme heat and pressure which is exerted throughout manufacturing and operational processes. Handling PCB assembly is a vital part, as any negligence can lead to a disaster. Sufficient care and caution are needed throughout. As PCBs are closely related to electronics, the primary focus here is on their functionality, rather than durability. They come with specific vulnerabilities.
To start with, a printed circuit board can function well if a few things are taken care of in the right way.
Important Factors to Consider While Taking Care of PCB
Certain issues in PCB functions are common, but following some handling patterns can take care of them and control them in the long run. Educating yourself about the ways in which handling PCB can be helpful holds great importance to preserve consistency in the usage. Following these practices can really help:
Least Physical Contact
Reducing the physical contact with PCB can minimise the possibility of having issues with it. It is said that the more you touch it, the more likely you are to end up damaging it. Instead of moving the PCB with your hand, it is always advisable to do so through the transportation rack. You can also use proactive gloves to reduce physical contact.
Applying the Right Tools
People always look for options with which they can control the possibility of damaging the PCB to the least, and to your surprise, there are several tools that might help, but for sure you are not aware of them. These tools made handling them easy. Check the list of tools that you should know:
- Magnifying glass – You have likely heard of it since childhood, but you may never have thought it could help with handling a PCB. Yes, it does, as with it, you can have a clear view of any detailed part that you need to work with. It is best if you use a robust magnifying glass or jeweller’s loupe. It also ensures that everything inside it is placed accurately.
- Electronic tweezers – These come in handy if the surface-mount components are too small to hold with an empty hand. By adding through-holes, it can verify that all components are in the correct position. Placing them with electronic tweezers is anytime better than placing them with bare fingers.
- Poster Putty- You would have seen that when experts work on a printed circuit board, they use something to hold small objects. It is nothing but poster putty. Even in cases where a PCB is pressed directly into the poster putty, it comes clean, leaving no residue.
Always Keep Your Workstation Neat and Clean
No PCB comes without connection points, and it is a known fact that if they come in contact with any impurity, their quality and durability deteriorate immediately. Here, the idea of keeping your workstation handy always helps. Do not let any mess clutter the area, and follow the maximisation of sanity rules. Remember to keep your hands clean when touching them. Reduced contact with PCBs with minimal impurity is always beneficial here.
Electrostatic Discharge is A Big No
Fact checking: If your PCB comes into contact with an electric shock of 3000 volts or less, it may end up with damaged internal circuitry. The reason behind this is the sensitive components present inside it. Electrostatic charges can actually be the reason behind the failure of PCB components. If the environment where a PCB is employed is non ESD safe, it can happen commonly. A wrist strap should always be attached to the earth ground while handling them to keep them safe. In some places, the use of ESD garments and footwear is also common. Regularly keeping an eye on grounding and resistance may also help in ESD protection.
Remove Moisturiser
If a PCB is exposed to moisture, it can attract several problems. Liquid that has the possibility of contaminating the PCB should be kept away from the PCB assembly area and workstations. Keeping them in protection bags when they are not assembled can also be helpful. Some of the PCB components available on the market come with tags that indicate how long they can be kept open before they start to be affected by moisture. Sticking to the date may help to safeguard it. Manage the required humidity level and use ionisers if needed for printing, placement, testing, or other static-prone processes.
Now, the question arises: Are the precautionary measures the same or different at different stages of PCB assembly? Although the primary goal is to ensure the complete safety, functionality, and durability of the PCB, the steps to preserve it may vary from one step to the next. Let’s explore them one by one:
Before Commencing The PCB Assembly
- Start by checking the design files to ensure they are created accordingly, including the correct Gerbers, BOM, and drill files. The assembly drawings allotted should be clear and followed correctly.
- Check for footprints correctness, thermal reliefs, and board edge perfections.
- Pen down the correct part numbers, avoid any duplicate entries and avoid as much as possible substituting any part without any expert validation.
Placement of Components
- Before placing any component, double-check that it matches the datasheet for electrolytes, IC pin 1, diodes, and other relevant details.
- Preserve all the SMT parts in constant orientation so that rotation mistakes can be avoided, and they can be placed smoothly.
- Completely ignore any improper misalignment or placement of PCB clamping and calibrated equipment. Being accurate while picking and placing data always ensures smooth functioning.
Maintaining Quality and Process Control
- Remember to get a hold of the right solder paste, printing parameters, and stencil thickness. Inspecting the paste volume and space before placing it always helps.
- The hand soldering technique should be either avoided or performed with extreme caution, as it can lead to solder bridges, cold joints, and sometimes component damage.
Final Inspection and Testing
- Practising AOI in functional or in-circuit tests can help to rectify the defects at early stages.
- Visual inspection is necessary to identify insufficient solder, orientation problems, solder bridges, and missing or incorrect components after through-hole soldering and reflow issues.
- Reworking documents and taking the right measures to ensure the next production is error-free and free from repeated mistakes should always be practised.
Wrapping Up
Any mishandling during SMT assembly or PCB assembly can lead to issues with the final printed circuit board. Working with experts under complete guidance can check that the final results obtained here are without any issues. One needs to be careful throughout, from the early stages of design to the final testing, so that no problems arise while handling delicate circuit boards.
