Printed Circuit Boards, PCBs, are at the heart of every electronic device. We interact with PCBs numerous times throughout our day – from laptops and cell phones to smart TVs and refrigerators – but most of us do not fully understand the basics of printed circuit boards. Below are the ins and outs of PCBs and PCB assembly technologies.

It should be noted that PCBs continue to shrink in size but grow in capability as the demand grows for more portable and higher functionality electronics including hand-held and wearable devices for consumer and commercial markets. High density circuitry is an amazing advancement that has enabled smaller, more tightly packed boards that are necessary for these devices. PCBA providers must keep up with the rapid PCB advancements and be able to assemble smaller, more complex boards without sacrificing quality. When selecting a PCB assembly supplier, it is imperative that OEMs choose a partner, like Riverside Integrated Solutions (RIS), that employs advanced PCB assembly technologies and is focused on meeting the challenges that PCB innovations often present.

In simplest form, PCBs consist of sheets of non-conductive substrate that are overlaid with conductive circuitry, typically copper, to provide the necessary conductivity. Common substrate materials include fiberglass and polyester. Electronic components, such as resistors, transformers, transmitters, and capacitors, are connected to the board and traces are used to connect the various components to form a functional circuit, or PCB assembly.

There are several different types of assembled PCBs. The type is selected based on the application of the electronic device, factoring in the desired functionality, complexity, and spatial limitations. Below are some common forms of PCBs.

· Single: these are the least complex and are easiest to manufacture. The boards have a single layer of conductive material and only occupy one side of the substrate.

· Double: as the name suggests, this type has conductive material on the top and bottom of the substrate.

· Multi: this type of denotes a board with more than 2 conductive layers. Multi-layer PCBs are most often 4-, 6-, or 8-layer boards and are utilized in more complex electronics applications.

PCB designers must also determine the level of flexibility in the printed circuit board. Traditional PCBs are rigid and inflexible, but flexible PCBs are gaining popularity. These are categorized as flex, which has more bend and is able to withstand more movement than traditional rigid PCBs, or rigid-flex, which is a hybrid option that offers the best attributes of both rigid and flex technologies. Rigid-flex PCBs typically contain flexible layers attached to one or more rigid boards. In order to remain competitive, PCBA providers must broaden their expertise to include flexible, rigid, and rigid-flex PCB arrangements and the associated assembly processes for each. When partnering with RIS, customers receive reliable, seamlessly-assembled printed circuit board systems built with extreme precision. To learn more about our PCBA expertise and solutions, watch our short video.

There are two primary techniques for joining components to the PCB during assembly: surface mount and through-hole. Each is described in more detail below.

· Surface Mount Technology (SMT): this technology is the most widely utilized for PCBA. As the name implies, SMT attaches components directly to the surface of the PCB using solder paste and does not require any holes in the board. This method allows components to be mounted to both sides of the board, allowing for more components on a given board and smaller PCBs compared to PCB assembly using THT only.

· Through-Hole Technology (THT): this technique runs component leads through pre-drilled holes in the PCB. This method is not utilized as frequently as SMT but is known for its reliability and strong connections that is some cases are able to endure more vibration and stress than boards assembled with SMT.

Below are the key steps in the PCB assembly process. The steps and sequencing may vary slightly depending on whether SMT or THT technologies – or a combination of both – are employed; however, the following describes the key elements of any PCBA process.

1. Apply Solder Paste: the first step in PCBA is to apply the solder paste to the sections of the PCB where components will be surface mounted. The paste is a mixture of solder and flux that is used to permanently join the components to the board in future steps.

2. Place the Components: the next phase is to place the necessary components on top of the solder paste. This step is often called “pick and place”. Depending on the functionality of the PCB, the components being added to the PCB may be resistors, capacitors, inductors, sensors, or other electrical parts.

3. Soldering: the purpose of this step is to permanently bond the components to the PCB. PCBA processes using SMT typically utilize a reflow oven and conveyor system during the soldering step to melt the existing solder paste. With THT, the component leads are inserted through the existing holes and a wave soldering method is often used where a wave of molten solder flows across the bottom of the board. In both cases, the molten solder joins the components and leads to the board. The assembly is then cooled to solidify the solder once again and fix the components in place.

4. Inspect the Assembly: this phase of the PCBA assembly process is crucial. Proper inspection is necessary to ensure the prior steps were performed effectively. This step may entail both manual and automatic inspections.

5. Testing: the final step in the PCB assembly process is testing to ensure the PCB functions as designed. There are various test methods such as flying probe, in-circuit testing, and others. Once testing is completed, the PCBA process is complete.

At RIS, PCB assembly is one of our core competencies. We provide reliable, seamlessly-assembled printed circuit board systems built with extreme precision. Our skilled engineers, technicians, and assemblers work to expertly put together a complete PCBA. When you choose RIS for your PCBA projects, you can expect the hands-on customer care of a small manufacturing operation and the capabilities characteristic of a much larger company with our complete electronics manufacturing services for OEMs in any industry. Our electronics assembly expertise includes:

· Surface Mount Technology (Fine-pitch, BGA (1 mm), µBGA (.4 mm), 01005, X-Ray, automated rework, and automated optical inspection (AOI))

· Magazine to Magazine handling

· Smart Shelving floor stock inventory control

· X-ray reel counting

· Lead-through auto-insertion (Axial, Radial, DIP, and Zierick Terminals)

· Wave Solder and Selective Solder Machines (No-clean & aqueous flux processes) RoHS and Tin/Lead capabilities

· Special Application Equipment (Robotic dispensing systems)

· Conformal coating (Silicone, Acrylic, Urethane)

· Potting (Epoxy, Urethane, and Silicone)

· Low-pressure molding technology

· Comprehensive product test

· 3D Printing

Contact us today at (507) 523-3220 to see how we can help with your PCB assembly needs, or click here for a quote.