How to improve PCB assembly process?

1. Know the PCB Assembly Process

After a design data collection stage delivers the Gerber data to a manufacturer, the PCB manufacturing process refers to the production of the bare board. The first step is to add the panel's substrate, which contains the insulating substance. Copper is then applied to the board and chemically etched away, leaving just the essential traces. Drilling, plating, and the installation of solder masks are also part of the PCB production process.

To make the PCB functional and ready for your project, only one component is installed on it. Surface mount technology (SMT), Pick and Position machines, and human soldering are all used to place electronic systems on the board.

You must choose a technology depending on your demands and the electronic components you are employing. To get the necessary results, you may need to mix PCB assembly methods such as the SMT assembly process and through-hole components technology.

2. customer relationship mining system

This will allow a manufacturing and assembly machine to effortlessly choose and position components on the PCB (PCB assembly process). Unambiguous communication is crucial for any activity, including the SMT). You must know what you want from your PCB provider. You don't want to take the risk of building your PCB without first learning about the requirements.

Please note down their interests as well as the electronics required for the project. Discuss the various technologies to determine which ones are appropriate for the assembly. You must also guarantee that your PCB provider understands your requirements and can satisfy your customers' expectations.

3. DFM / DFA Check

A DFM check guarantees that flaws in your PCB design are identified early on, allowing you to avoid mistakes and manufacturing delays. DFM is a thorough test that finds incorrect electronic components footprints.

DFM helps you to correct errors before they are sent for assembly by recognizing them before the assembly process. The testing also exposes any flaws that are superfluous, missing, or possibly harmful. These include incorrect component spacing, footprint corroboration, component to component spacing, component to edge spacing, initial pin indication, component polarity, diode cathode mark, and so on. A DFM check can efficiently detect and aid in the creation of a functioning and high-quality batch of PCBs that do not malfunction or cause shorts. 

DFM's mission is to minimize costs, accelerate delivery, and improve the entire product life cycle. DFM helps you to select the suitable parts for application and achieve your intended result, as even little errors can result in major losses that impair customer satisfaction. It also saves you money and effort on reworks.

4. Assembly Materials Inspection

The PCB assembly is all about arranging the various components on the board. You can also find them on your own. Regardless of the choice, you select, critical process parameters to verify the details before assembling the PCB.

A competent PCB assembler's product and process quality control department will be in charge of the data analytics process of the incoming materials. The experts will rigorously test the components to guarantee that they are functioning and can be utilized on your PCB without any issues.

Date code validation, material functional testing, and other tests to guarantee the components are in perfect functioning order are all part of the quality control inspection process. Materials review enables engineers to employ only high-quality components, resulting in longer shelf life for your PCBs.

• Amount and model numbers following the BOM list are among the elements examined by industrial and systems engineering engineers for arriving materials.
• Conducting sample testing with a multimeter, a test frame, and other tools.
• Deformation, oxidation, or fractured sections of complicated parts such as IC.

 5. SMT Solder Paste inspection machine

The placement of solder paste to the bare panel is the first step in the PCB building process. If you've ever seen a t-shirt is printed using a silkscreen, you'll have a good understanding of how things work. We provide PCB manufacture, Printed circuit board assembly (Surface mount technology devices), and other services. A thin stainless-steel stencil is applied over the PCB instead of a silkscreen. The stencil covers the whole board, leaving only the pads exposed to mount the WellPCB; we have specialists and experts on staff that have the necessary skill sets to bring your PCB demands to reality. The technique is carried out on a machine with the stencil held above the board by a mechanical device. An applicator then takes over and delicately spreads the solder by moving around the board.

Solder is only used in the exposed areas where the Surface mount technology parts will be installed. If you're working with double-sided PCBs, you'll have to repeat the operation on either side of the board.

The solder paste is created by combining powder metal solder with flux, which provides it with sticky characteristics. It's often grey and fuses the various components to keep them in place. The composition of the solder paste is determined by the nature of the application and the use of the PCB. In general, it comprises different amounts of copper, tin, and silver. 

6. PCB Assembly Process–Pick, and Place Surface Mount Device (SMD)

SMDs, unlike through-hole gadgets, do not have legs or connections and are glued to the PCB. SMDs are the most commonly utilized non-connector elements in PCBs. Engineers used to choose and put each part using tweezers, which took a long time and caused tiredness. We now have sophisticated machines that can 'select and place' SMD on target pads thanks to advances in technology.

Typically, the devices use a vacuum to pick up the components and position the PCB. The SMDs are then carefully placed on the PCB's selected positions on the solder. Depending on the number of SMDs you intend to utilize, you may need to do this step in various kinds.

7. PCB Assembly Process–Secure SMDs with Reflow Soldering

The SMDs are on the pad, and the following step is to ensure that they are securely fastened. That implies the solder must be heated and solidified in a process known as reflow soldering.

The PCBs are transported on a conveyor belt through an industrial oven, which warms the PCBs to 480 ℃. As a result, the solder in the solder paste melts as the PCBs continue to move on the belt.

This step is crucial because the SMDs are heated at significantly greater temperatures than manual and wave soldering. But don't worry, because modern SMDs are designed to endure high reflow soldering temps.

8. PCB Assembly Process– Time for X-Ray Inspection

Following the reflow soldering process, an X-ray inspection of PCB process performance is performed to discover quality problems and other issues. It's also utilized for pre-flow soldering inspection of bare boards throughout the production process.

The X-rays produce a digital image of the solder connections by penetrating the silicone of the SMDs and reflecting off the metal in the solder. To examine the photos, you can use image processing solutions. The X-ray examination approach is mostly utilized for multilayer and complicated PCBs since it allows you to see through the surfaces.

9. Final Inspection of the existing inspection process

One of the tests is an automated optical inspection, which uses cameras to automatically examine your PCB for quality and existing failure prevention processes. The system employs cameras positioned at various angles to detect faults such as absent solder, incorrect component placement, and solder shorts. Spot all problems with a single method via a single interface. Using the technique, you may process a huge number of PCBs in a short period.

You might also explore hand inspection, which is still utilized in the PCB business for small batches of PCBs. In-person visual examination is good for detecting flaws, but it takes time and puts pressure on the technicians. Other procedures, such as In-Circuit Testing (ICT) and Functional Circuit Testing (FCT), may be included in the final inspection cycle to ensure the operation of the electrical connections. The tests may be more expensive, but they ensure that the cause of any errors can be pinpointed.

Conclusion

Printed circuit board assembly is a multifaceted process that has gotten more effective as technology and robotics have advanced. There is less opportunity for error now, and the majority of PCB batches are perfectly functioning. Still, it would be beneficial if you kept the things we covered in mind to guarantee your PCB assembly process runs successfully. It would aid in the establishment of clear communication between your client and PCB assembler to do DFM inspections and verify arriving material. The use of machines ensures exact component positioning while the solder paste printing process successfully binds the SMDs to the PCBs.