Printed Circuit Board Assembly | A Step-by-Step Guide to PCB Assembly Printed Circuit Board Assembly A Step-by-Step Guide to PCB Assembly Menu Skip to content Home About Us Capabilities Contact Us Search for: Introduction Printed circuit boards (PCB) are used in nearly all consumer and commercial products whether it is a kitchen range with a digital display, a home entertainment center that’s streaming movies, or a programmable logic controller used in industrial automation. Assembling a PCB is complex process that requires special expertise, specialized equipment, and the procurement of a variety of electronic and electrical components. This article discusses the step-by-step PCB assembly process, including through-hole, surface mount and their soldering requirements. The Difference Between PCB Fabrication and PCB Assembly Manufacturing a PCB is two-step process: PCB fabrication and PCB Assembly. Let’s go through their differences. PCB fabrication focuses on manufacturing the unpopulated board itself. This includes, but not limited to, the number of layers, traces, blind and buried vias, among others. On the other hand, Printed Circuit Board Assembly (PCBA for short), takes the fabricated PCB and places all the components it and then solders them to the board. PCB assembly also includes testing the assembled board to ensures it functions correctly. Equipment Needed for PCB Assembly PCB assembly is an equipment- and resource-intensive process. Before we discuss the types of PCB Assembly, let’s review the equipment need for PCB Assembly, which includes: A fabricated PCB as per the customer’s specifications Electronic and electrical components (e.g. passives, semiconductors, active components, magnetics, etc.) Soldering materials and flux Soldering devices such as soldering stations, wave soldering equipment, surface mount (pick and place) machines, testing stations, etc. Types of PCB Assembly There are two main types of PCB assembly. They are: Through-Hole Assembly Surface Mount Assembly Through-Hole Assembly Through-hole assembly places electrical and electronic components with leads into holes drilled on the PCB and then binds them to it through hand and/or wave soldering. Plated through-hole assembly places the part in a plated hole, which requires a specialized soldering process other than the standard solder paste and stencil. Through-hole assembly used two types of soldering methods: Hand Soldering is used to solder components that cannot be placed via automated machines, such as some magnetic components. It is also used in PCB rework or repair jobs. Wave soldering utilizes a high-temperature bath containing molten solder. The PCB with its through hole components already placed on it is transported over the molten solder via a conveyor system. At the completion of the wave soldering process, the PCB is cleaned and tested. If the PCB is malfunctioning, it is re-directed back for rework. Surface Mount Assembly Surface mount assembly places leadless surface-mounted components on a PCB board designed to hold them. They are soldered to the surface of a PCB using specialized equipment, which is different from through-hole assembly equipment. Some PCBs only require though-hole or surface mount, However, in other situations PCBs both types of assembly will be utilized. It is important to understand each process, as well as when you need to use both types of assembly processes. Surface mount assembly equipment are automated pick-and-place machines that can pick components and place them onto the PCB prior to soldering. It uses reflow soldering to bind the components onto the PCB. Reflow soldering is a type of soldering where the board with all of its parts placed on the board is transported through an oven or furnace which melts the solder paste, allowing it to flow. Then it moves to a cooler, which solidifies the solder and thereby binding the components to the board. The final step is cleaning, inspection, and testing. The entire process can be summarized in the following steps: Apply solder paste to the PCB using a stencil. Place surface mounted components on the PCB with automated pick-and-place machines. Allow enough time for the solder paste to adhere components on the PCB and conduct reflow soldering process Inspect and test the assembled board for proper functionality, including visual checks and X-ray inspection. Place plated through-hole components on PCB and solder, accordingly. When required, perform manual and wave soldering of through-hole components when both types of assembled parts are on the PCB Perform a final functional inspection to verify electrical characteristics. Conclusion Anyone involved in product development can benefit from some knowledge of Circuit Card assembly. In this article, we discussed the different types of PCB assembly, along with the three types of soldering, and the difference between PCB fabrication and assembly. Each type of PCB assembly is important to know. There are advantages and benefits to both types of PCB assembly, through-hole and surface mount. The deciding factor for using either type or a combination of both depends on the design and application. The surface mount assembly process is usually faster than other processes, but it may not be the ideal option for your design. You will need to work with your PCB assembly company to determine which process is best. Proudly powered by WordPress