The Surface Mount Technology (SMT) process has revolutionised the electronic manufacturing industry, enabling the compact and efficient assembly of electronic components on printed circuit boards (PCBs). SMT has become the cornerstone of modern series electronics production by integrating advanced techniques, such as solder paste printing, automated component placement, and precise soldering.
What are the most crucial stages that drive the SMT process forward, shaping the modern electronic landscape? See below!
The solder paste printing stage is a crucial step in the surface mount technology process for electronic component assembly on a printed circuit board (PCB). Delicate and precise, it demands the experience and expertise of skilled engineers to apply solder paste with meticulous accuracy onto the PCB.
The success of this stage lies in the intricate interplay between component size, pad dimensions, and specifications outlined in the datasheet. It is fascinating to witness how the quality of the entire SMT line hangs in the balance, with any imperfections during soldier paste printing potentially impacting up to 60% of the overall defects.
Utilising sophisticated robotic systems, this stage ensures accurate positioning of components with exceptional speed and efficiency. The pick and place stage in the Surface Mount Technology process involves the precise placement of electronic components on a printed circuit board (PCB), considering each component's unique parameters.
Different passive elements, such as capacitors and resistors, are applied with high speeds, while components requiring greater precision, such as IC, BGA, FPGA are handled at lower rates. The average operating speed of the Pick and Place machines is approximately 50,000 components per hour, ensuring efficient and accurate assembly of electronic devices. This stage showcases the flexibility and adaptability of SMT processes, catering to diverse component requirements while maintaining high productivity levels.
Original Equipment Manufacturers (OEMs) are organisations that manufacture or sell products to another company. This company then uses these components in part of a wider process to create products for their customers under their own branding. A big part of creating products to sell on to other companies centres around the SMT process.
Surface mount technology (SMT) is the process wherein components are mounted onto the surface of a printed circuit board. The components are designed specifically to be directly mounted, rather than hardwired, onto the circuit board for the vast majority of electronics.
Surface mount technology has been widely used since the 1980s. This is because the SMT process is automated, meaning it saves time and costs for both the manufacturer and the customer. Previous methods used hand wiring through holes between the boards to bring components together, meaning this needed manual labour to do so and of course, risked human error. The SMT process is also more adaptable for technological advances in the future than the through hole wire method.
Other advantages of surface mount technology include higher component density and smaller components for mounting alongside better performance under pressure. Using surface mount technology also means that either side of the board can have components mounted on it.
There are three main steps to the process when it comes to surface mount technology which cover solder paste printing, component placing and reflow soldering.
The solder paste printing process is carried out by a machine to ensure accuracy and speed.
During this part of the assembly, a printer applies solder paste using a pre-made stencil of the PCB and squeegees. This solder paste is usually a mixture of flux and tin and it’s used to connect the SMC and solder pads on the PCB.
During this part of the process, it’s vital that each pad is covered in the correct amount of paste. If not, a connection will not be established when the solder is melted in the reflow oven (more on that later).
Controlling the quality of the solder paste printing process is vital. This is because, if any printing defects are left undetected at this stage, they will lead to other defects further down the line. For this reason, the design of the stencil is key and care must be taken by the assembly team to ensure that the process is repeatable and stable. Thankfully, to smooth the process, most solder paste printers have the option of including an automatic inspection.
However, sometimes external machines are used to assess the quality of the printing. These solder printer inspection machines use 3D technology and allow for a more thorough inspection. This is because they check for things like solder paste volume per pad, rather than just the print area.
Once the PCB has passed inspection, it moves to the component placement phase of the SMT assembly process.
During this phase, each component that will be mounted on the PCB is removed from its packaging using a vacuum or a gripper nozzle. Following this, a machine places it in its programmed location. Not only are the machines that carry out this process highly accurate, but they’re also incredibly quick. Some of the most advanced machines can place 80,000 individual components every hour.
When all the individual components have been placed on the PCB, they must be inspected to ensure that they’ve been placed correctly. This is an incredibly important step in the process, because if any placement errors go undetected and the parts are soldered into that position, then this can lead to high volumes of rework, which can be both costly and time-consuming.
Once the placed components have passed their inspection, the process moves to the reflow soldering phase. During this part of the SMT process, the PCB is placed into a reflow soldering machine (some people refer to them as reflow ovens).
Here, all the electrical solder connections are formed between the components and the PCB. Using heat, the solder paste applied earlier is converted into a solder. Again, accuracy is vital during this stage of the process because if the PCB is heated to a temperature that’s too high, the parts or assembly could become damaged and the PCB won’t function as intended. If the temperature is too low, a connection may not be established.
To ensure the best results, all PCBs within the soldering machine are placed on a conveyor belt. They’re then heated gradually in a series of zones before being passed through a cooling zone.
To avoid joint defects, the PCBs must stay in each zone for the correct period of time. The PCBs must then also be entirely cooled before they’re handled or moved. If not, they may warp.
After the PCBs have been through the reflow solder machine, they are inspected one final time. This inspection is usually carried out by a 3D automated optical inspection machine (AOI). This is to ensure that the solder joint quality is as expected and that no mistakes have been made during the SMT process. Machines are used for this process because they’re much quicker than humans, and more accurate in their analysis.
ABL Circuits offers a tailored and personal service for all OEMs. We are a one-stop shop for all your PCB manufacturing needs, and can take the entire process from start to end off your hands, or alternatively, assist with an individual aspect along the way.
We are a family run business which began modestly at our founder, Mark Leverett’s home. 36 years on, William Leverett is now director and is helping to run the company with his father. Family is at the heart of everything we do, which means you get a personal and passionate service.
With over 36 years of experience under our belt, ABL Circuits has a wealth of knowledge across our employees, alongside the newest state of the art technology. As one of the only manufacturers that offer the full start-to-end process, in-house, for PCB assembly, we can help to guide you through every step.
We work with a range of SMEs and bigger companies and know that it is not ‘one size fits all’ when it comes to budget and delivery. We work closely with each of our customers to understand what they are looking for and how we can provide this in the most cost efficient way, without compromising on quality.
If you’d like to find out more about how we work and how we can help you, get in touch for a free quote.
Comments
Please Join Us to post.
0