It’s unfortunate that there are still people in the world who don’t understand what a circuit board is or why people in our profession must design them. Thankfully, most people do understand the importance of PCBs and their uses, but very few understand the design and manufacturing processes required to build them. To help, we have put together a PCB flow chart that describes the design and assembly processes and how the two interact with each other. For clarity, we have omitted the fabrication process—other than to note the procurement of raw PCB fabs; otherwise, the following should help to simplify the overall process.
The PCB Flow Chart, from Schematic Capture to Component Placement
The first section of the PCB flow chart depicts the PCB design’s front end, including library development, schematic capture, and circuit simulation. Once completed, the schematic is used to drive the board’s physical layout, and the flow chart continues with database preparation, component placement, and critical nets routing. You can also see different points of design checking and review throughout. In a parallel process, the contract manufacturer will receive the initial data from the PCB design for a bill of materials review and begin sourcing the components. The manufacturer will also work with the design team to develop the physical layer structure and board configuration and review the component placement for manufacturability (DFM).
The design team needs to include the PCB CM early on to ensure that the components selected are available and cost-effective for manufacturing. The CM is also available to help the design team with board layer configurations to ensure the best signal and power integrity in the final design.
The Layout Flow Chart, from Trace Routing to Manufacturing Review
The middle section of the flow chart starts with critical net trace routing and review in the PCB design. Once this step is approved for signal and power integrity, the remainder of the board will be routed. During design cleanup, the layout team will run their DRC checks and finalize details such as the silkscreen, solder mask, and solder paste layers. All of this will then go through a final layout review. Once approved, the design is ready for the generation of the artwork files and manufacturing drawings, which will then be sent to the contract manufacturer. The PCB CM will then conduct their manufacturing review to ensure that the circuit board is ready to be built.
It is essential to follow the design parameters already submitted to the PCB CM during layout. If anything changes, it is imperative to update the CM to avoid bad board builds. Some of the changes to look out for can include impedance values for sensitive routing, layer configurations, and material requirements.
The Manufacturing Flow Chart, from Design Input to Circuit Board Delivery
The final portion of the flow chart depicts the assembly of the circuit board, starting with the customer report generated by the manufacturing review. This report gives both design and assembly a chance to make any last-minute changes to the board before manufacturing begins. With final design approval, the PCB CM will order raw PCB fabs and finalize part procurement. Once the materials, fabs, and components are received, incoming inspection will validate them for assembly preparation. At this point, the circuit board will be assembled using various processes, depending on the type of components used and the board configuration. Any assembly issues detected by the different inspection techniques will be resolved by manual rework. Lastly, automated testing will validate the assembly process.
The circuit boards are now ready for their final inspection, packaging, and shipping to their final destination. With the collaborative efforts of both design and assembly, the final circuit boards will be efficiently assembled and at the highest levels of quality for their best performance and operation.
At VSE, we have used this workflow for over 35 years to deliver the best results to our customers needing high-quality electronics built quickly and precisely. Our staff, from design engineers to manufacturing technicians, are focused on delivering the quality you need for a successful design.