Printed circuit boards (PCBs) are critical in producing nearly every modern electronic device, from smartphones and personal computers to the industrial machinery used in manufacturing facilities. Depending on the type of PCB and its end application, there are a few main types of electronic assembly processes manufacturers can choose from. Regardless of the assembly method, all PCBs must undergo rigorous quality assurance checks before being installed in their final products.
Learn more about each of these PCB assembly processes and the quality assurance measures necessary to produce high-quality PCBs.
Types of PCB Assembly Processes
All electronic assembly processes involve electrical components being mounted and connected on a PCB to create a functional product. However, each assembly process offers distinct advantages depending on the PCB’s intended application.
Here is a breakdown of the different types of assembly processes and their most common use cases.
Surface Mount Technology (SMT) Assembly
Surface mount technology (SMT) has become the standard process for modern PCB assembly. In this basic process, the components are mounted directly onto the surface of the PCB without the need to drill holes. This allows for smaller, more efficient designs and is ideal for high-volume, automated production. Common applications for SMT assembly include PCBs for:
- Smartphones
- Computers
- Home appliances
- Industrial equipment
Through-Hole Technology (THT) Assembly
Through-hole assembly used to be the go-to method for mounting components on PCBs. In this process, component leads are inserted into pre-drilled holes on the board and soldered in place. Even though SMT is currently considered the industry standard, there are still some use cases for through-hole assembly, including:
- Large transformers
- Electrolytic capacitors
- Connectors (e.g., headers, jacks, plugs)
- Diodes and transistors
Rigid-Flex Printed Circuit Board Assembly
Rigid-flex PCB assembly combines the durability of rigid boards with the movability of more flexible substrates. These boards are built with multiple layers of flexible circuit materials that are connected internally or externally to one or more rigid boards. This results in a versatile PCB that can be folded or bent during installation, making it ideal for applications where space is limited. Common applications for rigid-flex PCBs include:
- Wearable devices
- Laptop computers
- Smartphones
- Automobiles
- Testing equipment
Mixed Assembly
As the name implies, mixed assembly combines assembly techniques, particularly SMT and THT. Mixed assembly combines the features and advantages of these techniques, such as soldering and secure through-hole mounting, to ensure that all components are mounted securely. Common applications include:
- LED lighting
- Sensor boards
- Server boards
- Video processing equipment
Ball Grid Array (BGA) Assembly
Ball grid array (BGA) assembly is an advanced technique used primarily for mounting microprocessors and other integrated circuits. The chip is mounted to the PCB using a grid of small solder balls on the bottom of the package. This allows for more connection points than traditional methods, improving the performance and reliability of high-speed electronics, such as:
- Smartphones
- Computers
Quality Assurance Practices for Electronic Assembly
Verifying quality at every stage of the PCB assembly process is essential. Without rigorous quality assurance (QA) practices in place, even the best-designed PCB can fail. This can lead to devastating setbacks and a significant loss of time and money.
Here are some key QA practices to look for when choosing a reliable PCB assembly partner:
- Certifications: Look for ISO, AS9100, and ITAR certifications that demonstrate a manufacturer follows strict quality control practices and meets industry safety standards.
- Experience: Manufacturers with an established reputation in your industry are likely to produce the best results for even the most complex PCB assemblies.
- Inspections and rigorous testing: Effective QA inspection and testing combine human oversight with automated systems to catch defects and ensure the final product is ready for its end-use environment.
PCB Assembly Services From Circuit Pak
The complex process of PCB assembly involves choosing the right method based on the project’s needs while maintaining the highest levels of quality throughout production. Partnering with a trusted manufacturer that follows strict quality assurance practices is essential to your project’s long-term success.
Founded in 1983, Circuit Pak is an experienced contract manufacturer and assembly provider for PCBs. Equipped with advanced automated production lines, we offer all the main types of PCB assembly techniques, including SMT, THT, mixed, and BGA assembly. We perform all production and quality control processes from our 50,000-square-foot ESD-controlled facility in Dayton, Ohio.
Request a quote to learn how we can help bring your next project to life.