It's important that your board build meets every single one of your operational and reliability requirements, irrespective of its application. While the old lack box model assigned separate responsibilities for meeting those demands, operation was the engineer or designer’s sole domain and the contract manufacturer (CM) determined how long the board would last.
Fortunately, this perspective is rapidly being replaced by a white box approach to manufacturing—a more collaborative model that emphasizes the use of DFM by engineers and the understanding and maintaining of design intent by CMs during manufacturing. Leveraging this manufacturing approach for high-quality production begins with optimizing the PCB fabrication process.
The PCB Fabrication Process
IPC-6011 sets the minimum standards for board fabrication and assembly. This includes parameters and specifications based on operational and reliability expectations for three performance classifications. For all classes, however, PCB fabrication consists of the following steps.
| PCB FABRICATION PROCESS | ||
| Steps | Procedure | Description |
| Step 1: | Imaging | The first step in fabrication is to create circuitry images. This is done for the top and bottom layers of all boards and for the internal layers of the stackup for multilayer designs. The copper layers are covered with photoresist and exposed to light. |
| Step 2: | Etching (inner layers) | Etching is the process of removing copper from all areas excluding traces or other conductor points. An ammonia-based solution is often used. |
| Step 3: | Layer stackup | For this step, the board layers (substrates and laminates) are stacked, aligned, and heat-pressed together. |
| Step 4: | Hole drilling | Vias and mounting holes are drilled through the layers. It is important here to follow the right drill process and adhere to aspect ratio limitations. |
| Step 5: | Etching (outer layers) | For the outer layers, photoresist and excess copper must be removed. |
| Step 6: | PCB plating | Plating drilled vias with copper enables current flow between layers. |
| Step 7: | Solder masking | Solder mask, a thin polymer film that’s typically green, black, red, yellow, or white, provides protection for non-conductive surface areas. |
| Step 8: | Silkscreen application | This is where labels, polarity symbols, pin 1 indicators, and other information are printed on the board surface. These are often applied by an inkjet printer. |
| Step 9: | Adding surface finish | The primary function of surface finishing is to guard copper areas from environmental hazards, especially moisture and oxidation. |
PCB fabrication creates the bare board or PCB without any components, and it shouldn’t be confused with PCB assembly (PCBA) where components have been soldered onto the board. This first stage of circuit board manufacturing depends primarily on the CM’s process and equipment. However, the design choices you make help determine if your board fabrication is optimal.
The PCB Design Development Checklist
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Ensuring a High-Quality Board Build
Defining quality for a manufacturing process can be difficult. Nevertheless, criteria such as standards compliance, the application of best practices, and the utilization of advanced technology are reliable ways to assess a CM’s PCB fabrication process. Further assuredness is possible by following these guidelines.
Guidelines for a High-Quality PCB Fabrication Process
- Determine the best IPC classification for your design.
- Familiarize yourself with every fabrication process step.
- Choose a CM with a quality-certified process.
- Acquire your CM’s DFM rules and guidelines.
- Choose the best materials for your design.
- Create an accurate, comprehensive manufacturing package.
- Collaborate with your CM’s methods and equipment to synchronize your design intent.
- Employ pertinent PCB testing for fabrication and assembly.
Tempo's Custom PCB Manufacturing Service
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Following the aforementioned list of guidelines not only aids your CM, but also allows you to make a significant impact on the quality of the PCB fabrication process and the boards produced. Tempo Automation leads the industry in rapid, high-quality PCBA prototyping and on-demand production. Partnerships with us are symbiotic relationships that thrive on meeting, exceeding, and optimizing every board we build with you—regardless of its application.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.
If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on how to ensure a high-quality PCB fabrication process, contact us.