The technological revolution moves fast, and you cannot lag if you want to remain relevant and competitive. Such has proved the trend with printed circuit boards, especially in electronic design, manufacturing, and assembly. So are you an electronics PCB designer or enthusiast ready to understand more about the embedded PCB, new kid on the block? You cannot imagine a modern printed circuit board without the embedded PCB design coming to the fore.
More recently, an increase in demand for wearable, electro-medical, and mobile devices has permeated every corner of the world. Consequently, demand for embedded PCBs increased, but a progressive size reduction of embedded PCBs. However, with the need for new attributes such as high-resolution display and wireless connectivity on devices, an increased pressure regarding increased component density on a reducing size poses exist and poses an unprecedented challenge that this PCB seeks to solve.
So what does an embedded PCB implies? An embedded PCB infers a printed circuit board containing embedded components to increase its efficiency and ensure high performance. It always features an embedding technology that becomes instrumental in reducing transmission losses and shrinking the interconnection path among components. It plays a central role in the miniaturization of printed circuit boards, function integration, IP protection, and increased reliability.
The Assembly Process for Component Embedded Printed Circuit Board
One key feature of an embedded PCB design entails embedded components in PCB, with the embedding process encompassing the embedded technology. The embedding technology includes mounting and involves two types: the Solder pad and the Thru-hole mounting methods.
- Solder pad mounting method. It involves the Bare dire and the Chip mounting processes. Firstly, the Bare method entails a wire mounting process or Flip-flop mounting. It would help if you chose which to go through with when trying to embed components on the PCB. Secondly, PCB in embedded system can also entail Chip mounting, where you can decide to adopt Wave soldering or Conductive resin.
- Thru-hole mounting method. It also entails the Bare and Chip mounting processes, though the subsequent options differ from the Solder pad mounting methods. Here, the Bare mounting entails the Plated thru-hole or Conductive adhesive thru-hole options. The Chip mounting route also contains the same options: Plated thru-hole or Conductive adhesive thru-hole options.
Please note that the mounting method involving the embedded PCB with pad requires assembling the components on the formed electrodes besides developing the electrical connections. The application of the insulating resin can then get carried out to bury and fill the electrode and components, respectively.
Assembly Procedure for Embedded Components in PCB
Before looking at the assembly procedure, it becomes necessary to note the following down during the assembly process. Firstly, use the die bonding for bare die components and mold package for pad components. You can also use WLCSP, CCCC, Ultrasonic wave bonding, ESC, and conductive resin. However, for AD mounting, you can opt for conductive resin and wave solder.
To better understand the assembly process for component embedded PCB, it becomes crucial to take one mounting method in perspective and look at it in depth. So in this article, the embedded tech involving pads will become the mounting method on focus as an incredible example.
Assembly Procedure for Embedded Tech with Pads
- Firstly, it becomes prudent to research technological and design procedures, especially when it comes to AD (buried into the PCB) tech feasibility and SMDs also embedded into the cavity of the PCB.
- Trace design is the next integral step.
- The embedded PCB’s manufacturing procedure comes as the subsequent step, and it involves a process. For a double layer PCB, it starts with the fabrication of the double-layer substrate before the coating of the solder paste. It then continues with the IC assembly and waves soldering before the insulation filling and mid-stack-up. Finally, the process ends with the top layer stack-up and hot pressing.
- Assembly embedded components in the cavity
- One key challenge with embedded that anyone will attest to involves the assembly of components in the cavity. You can face the possibility of failing to apply the old-fashioned solder paste printing tech of the planar pattern. In contrast, the smooth exhaustion of the gas in the cavity fails during the wave soldering. Consequently, it can all lead to high solder voidage. To avoid the occurrence of this scenario when using the vacuum wave soldering and solder printing techniques, the adoption of this workflow becomes crucial—printing of solder paste, mounting, and vacuum wave soldering. After that, plugging, cleaning, and spray coating ensues before the process ends.
Printed Circuit Boards Design for Embedded Systems
The PCB design when it comes to embedded systems proves critical in an embedded PCB manufacturing process. Because of this, it becomes instrumental in knowing a few things about the PCB designs for such embedded systems.
- PCB size. Size often represents a major obstacle in the design of PCBs. Therefore, the printed circuit board size and layout need every party, from the designers to engineers, to agree on everything. However, one non-negotiable includes a specific minimum size limit that PCBs cannot go beyond. It cannot get too small because you have to ensure that the right component positioning happens and avoids overheating. The embedded system has passive components, and thus the need for an SMD tech becomes mandatory. It reduces the distance and footprint between components and thus results in a compact printed circuit board layout. The second aspect entails the optimization of the PCB routing. Additionally, if space permits, it becomes crucial to increase the layer number and trace placement.
- Components placement. Placement of the components often follows and reflects the PCB design rules. The rules involve an excellent alignment that allows a simple assembly and soldering process. Additionally, a proper separation has to get enforced between digital and analog devices. Finally, try and avoid placing some of the heavier components at or near the PCB edge, as the board can bend.
- Thermal management. Heat tends to get produced on a printed circuit trace whenever a high-intensity current flows through it. Therefore, it becomes crucial to enhance thermal dissipation as you keep the size of the PCB small. You can accomplish this through one of two techniques or a mix of both. It can involve increasing the thickness of the trace or develop the PCB regions to achieve heat dissipation. Because of this, ensure that you adhere to the suggested IPC2221A standard. It entails the copper planes having a thickness of 10 ounces, though the value can always increase. Additionally, the creation of hot spots should get eliminated by keeping the PCB maximum temperature under 170 ͦ C. You can always use a thermal imager to determine these hotspots. Another crucial way of enhancing heat dissipation also entails the insertion of thermal vias (holes drilled in the PCB substrate)
- Embedded components. Most embedded systems feature small footprints and an elevated device density, all aimed at simplifying the assembly and design phases. Consequently, the resistors, inductors, and capacitors have to get embedded within the printed circuit board. It reduces the trace length, the number of solder points, besides the costs. What you achieve through this entails improved electrical performance besides circuit reliability. Capacitors, inductors, and resistors get placed on inner layers by etching in the PCB manufacturing process. Subsequently, these components get incorporated during the PCB’s multi-layer lamination process. Inductors include those with magnetic cores, as the cores composed of ferromagnetic components get embedded within the substrate. Finally, the inductive windings get developed through photolithography.
Based on the components, diverse embedded tech variants can get deployed during the incorporation process. It results in new solution approaches and apps. However, in this, you will have to delve deeper into the different embedding technology variants, the process flows, design rules, selection criteria for the correct embedding variant, and the ET project’s workflow. Fortunately, you have already covered some of these processes by this point, and it should not become harder to comprehend.
Step-Wise Process of Planning and Designing a Printed Circuit Board Assembly for Embedded Systems
- Define the requirements. All designs need specified requirements, and you will have to set some before embarking on the assembling process. Define what the assembly requires and what will not become necessary in the process. Such entails the connection of parts and the size of the PCB.
- Create a schematic. Once you have stipulated all the design requirements besides creating a concept to satisfy these needs, you will need to develop a comprehensive schematic. It should elaborate on all the components the PCB requires, the positions on the board, and the necessary connections between them. Of course, you also have to develop the bill for all components at this stage, and these involve material needs, current, and voltage requirements.
- Automation software for electronic design. It helps when it comes to the incorporation of details once the schematic gets developed. The set of instruction here become instrumental in the assembly process.
- Picking the method of fabrication
- Here, the original requirements, budget, time required, and available resources will dictate what fabrication method to pick. However, all these bases get covered at RayMing PCB & Assembly Company to ensure your design specifications get produced.
- Testing. It encompasses the last step, and it involves the prescription of what tests to subject the PCB assembly in ensuring that all design requirements get fulfilled. However, diverse testing techniques exist, and you will have to pick one that covers all the bases.
Embedded PCBs have become integral to all electronic devices because of the diverse specification needs users require. Therefore, if you want universal success and acceptance to your PCB design and one that outlives this period, an embedded PCB has to be your go-to PCB. Further, where better to get these services but on RayMing PCB & Assembly.