Step by step guide to electronics assembly

Precise design and electronic assembly of PCBs is crucial to the success of any device. In our article, we will discuss the two dominant component assembly technologies. Surface mount technology (SMT) and through-hole assembly (THT). You’ll learn about the important role that design files, such as Gerber, play in communicating accurate information between designers and manufacturers. We’ll also look at alternative file formats. Learn how precision electronics assembly and manufacturing can ensure the reliability, efficiency and success of your product in the marketplace.

Assembling electronic components is a key stage in device manufacturing. The use of proper assembly techniques and practices affects the quality, durability and reliability of the final products.

The importance of design in PCB production

Designing printed circuit boards (PCBs) is one of the most critical stages in the production process of electronic devices. It is during the design phase that the functionality, reliability and cost-effectiveness of the final product are determined. A good design is the foundation on which the entire production and assembly of PCBs is based, and any errors made at this stage can have costly and time-consuming consequences in later phases.

Key aspects of PCB design:

1. An electronic schematic is a graphical representation of the electrical connections between components. Every component, from resistors to microcontrollers, must be accurately placed and properly connected. An accurate schematic ensures that the circuit works correctly and minimizes the risk of errors later on.
2. PCB layout is the arrangement of conductive paths, holes, and pads on a board. It includes all PCB layers, such as copper layers, solder masks, and legends. An efficient layout ensures optimal electrical and mechanical performance, minimizing electromagnetic interference (EMI) and improving heat dissipation.
3. Good design practices include design principles such as proper spacing between paths, appropriate path widths, avoidance of sharp turns, and consideration of DFM (Design for Manufacturing) and DFT (Design for Test) rules. Adherence to these principles ensures that the design will be easy to manufacture, test, and assemble electronic circuit boards,  which reduces costs and shortens the time to market.
4. Choosing the right PCB assembly technique. There are two main types of electronics assembly: SMT assembly and THT assembly.

Importance of project files

In the printed circuit board (PCB) manufacturing process, accurate communication of design information is crucial to ensure high quality and technical compliance. PCB design data files are essential for communication between designers and manufacturers. These files contain detailed information about copper layers, solder masks, legends, and drill holes, allowing the design to be accurately reproduced on the physical PCB.

• Accurate design files eliminate misunderstandings and errors between designers and manufacturers.
• Optimized design files allow for faster and more efficient production processes.

Gerber files are the most widely used format for communicating PCB information. They enable every aspect of a PCB design to be accurately represented. These files are widely accepted by PCB manufacturers worldwide and supported by most PCB design CAD software.SMT/ SMD and THT assembly – differences

SMT/ SMD AND THT assembly – differences

Electronics assembly technology encompasses various methods of assembling printed circuit boards. SMT and THT are the main techniques used in the assembly of electronic devices. SMT electronics assembly uses SMD electronic components that are mounted directly onto the surface of the printed circuit board, allowing miniaturization and higher packing density. THT involves threading the leads of components through holes in the board and soldering them together, which provides greater mechanical strength. The choice between these techniques depends on the specific design and requirements of the device.

Guide to the manual surface mount of electronic SMD components

SMT/SMD assembly, or surface mount assembly of SMD electronic components, is a technique that involves mounting electronic components directly onto the surface of a printed circuit board, instead of through holes as in THT technology.

Tools:

• Hot air soldering station – For heating and soldering components.
• Tweezers – For precise placement of components on the PCB.
• Solder paste – A special paste containing flux and tin microspheres, used for soldering SMD components.
• Hotplate – For even heating of PCBs during soldering.
• Microscope or magnifying glass – For precision assembly and inspection.
• Solder paste template – For precise application of paste to PCB pads.

Materials:

SMD components – Resistors, capacitors, diodes, transistors, integrated circuits, etc.

PCB – With pre-designed pads for SMD components.

Flux – To improve the quality of solder joints.

The SMT assembly process begins with a thorough cleaning of the circuit board. Solder paste is then applied to the pads using a stencil or syringe. The next step is to precisely assemble the components onto the solder paste-coated pads. Then it is on to soldering, using a hot air soldering station or a reflow oven. The soldering station should be set to a temperature between 220-250°C and, in the case of a reflow oven, the soldering cycle of the electronic components should be run according to the temperature profile. At the end, a visual inspection and testing of the devices are carried out to ensure that all connections are correct and that the components function as expected.

Troubleshooting

• Solder bridges can form between adjacent pads, which is problematic. To remove excess solder and eliminate bridges, use a solder sucker or solder wick. 
• Insufficient soldering of electronic components results in poor solder joints. To address this issue, ensure the temperature is correct and the solder paste is well distributed. You can also add more flux. 
• Displacement of electronic components can occur during soldering, which is problematic. To prevent this, ensure the solder paste is well distributed and apply gentle pressure with tweezers during soldering.

Tips and tricks

1. Keep circuit boards and tools clean to ensure good solder joints.
2. Set the appropriate temperature on the soldering station to avoid damaging electronic components.
3. Practising SMD assembly regularly will lead to better results and precision.

Guide to manual THT assembly

The assembly of components using THT technology (through-hole technology) for electronic components involves threading the leads through holes in a PCB and soldering them on the opposite side.

Tools:

• Soldering iron – For manual soldering of component leads. The recommended power rating of the soldering iron is 25-50W.
• Soldering tin – Soldering material used to make connections. It is best to use tin with flux added.
• Desoldering pump – For removing excess solder or correcting solder joints.
• Tweezers – For precise placement of components on the PCB.
• Microscope or magnifying glass – For precision assembly and inspection.
• Soldering iron stand – To safely place a heated soldering iron.
• Soldering iron cleaning sponge – For cleaning the soldering iron tip from tin and flux residues.

Materials:

• THT components – Resistors, capacitors, diodes, transistors, integrated circuits, etc.
• Printed circuit board (PCB) – With holes for component leads.
• Flux – To improve the quality of solder joints.

The process of assembling THT electronics begins with thorough cleaning of the PCB to ensure good adhesion of the soldering tin to the pads. The components are then placed on the board and their leads threaded through holes in the PCB. Soldering is done by hand using a soldering iron and soldering tin. The soldering iron should be set to the correct temperature (approximately 350°C). Heat the component lead and pad on the PCB at the same time, adding soldering tin to spread smoothly around the lead and pad. Remove the soldering iron when the soldering tin evenly coats the joint. After soldering all the components, perform a visual inspection and test the devices to ensure all connections are correct and the components are functioning as expected. Make sure that all connections are shiny and have a volcano shape, and check for any cold solder joints or solder bridges.

Troubleshooting:

• Poor solder joints, make sure the soldering iron is properly heated and you are using enough flux.
• Solder bridges, remove excess solder with a desoldering pump or solder braid.
• Moving components, make sure components are securely attached to the PCB before soldering.
• Cold solder joints occur when the soldering iron is not heated enough or the soldering time is too short. Reheat the joint and add a little flux.

Tips and tricks:

• Keep your tools and PCBs clean to ensure good solder joints.
• Practice soldering regularly to gain better precision and control over the process.
• Use the correct amount of soldering tin and flux to ensure strong and durable connections.
• Regularly clean the soldering iron tip on a damp sponge or special brass sponge to ensure effective heat transfer.
• Make sure you have a well-lit work area and work in an ergonomic position.

Why choose contract electronics assembly?

Self-assembly of equipment is a complex process that requires precision to ensure the highest quality of the assembly. For mass production and contract manufacturing, automated assembly can significantly increase productivity and repeatability. It is therefore worth considering collaboration with EMS (Electronics Manufacturing Services) companies that have the resources and experience in automated assembly, production management, and component supply chains to ensure high quality and efficient production.

PCB prototyping and assembly

When designing a device, it is useful to create a prototype first to test the functionality of the device. Assembling prototype PCBs often requires both SMT and THT techniques to thoroughly test various aspects of the device design. Electronic assembly companies offer a wide range of services, from SMD and THT assembly to mechanical assembly, which are crucial for assembling controllers and other complex devices. Assembling an electronic board can be complex, so it makes sense to turn to EMS providers who have the experience and resources to professionally perform such tasks.

Benefits for OEM Companies

OEM (Original Equipment Manufacturer) manufacturing companies can leverage external manufacturing service providers to reduce assembly costs and focus on their core competencies. DFM (Design for Manufacturing) services help optimize product design, reducing production costs and increasing the quality of final products. Collaborating with a professional EMS manufacturing service provider ensures not only high-quality assembly but also efficient component supply chain management.

Outsourcing is extremely convenient for companies that do not have their own assembly line. It allows them to focus on product development and innovation while an external partner handles production and logistics. This enables companies to significantly reduce operating costs and bring products to market faster, while maintaining high quality standards.

Put your mind at ease with Device Prototype

The use of proper assembly techniques and practices ensures high quality and reliable end products. Accurate and precise placement of components on PCBs, proper soldering of electronic components, and meticulous inspection and thorough testing of devices are essential to avoid problems that can lead to equipment failure. If you need professional services, Device Prototype offers comprehensive SMT and THT assembly as well as PCB design services. With extensive industry experience, our team of experts is ready to assist you with every aspect of your project. To learn more about our comprehensive assembly services and to see how we can support your project development, contact us!