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PCB Fabrication and Assembly Checklist: Things to Check Before Design Submission

 Jan 20, 2021

PCB Fabrication and Assembly
Designing a printed circuit board is a long and complex process. This is because of the complexity of the designs, performance specifications, an increasing number of components, and so on. Most of the circuit board manufacturing errors occur due to the complexity of components and their wrong placement, lack of accessibility to drawing during the assembly phase, and many more. This is where making a PCB fabrication and assembly checklist would help. This design checklist ensures the circuit board will be fully manufacturable, testable, and sourceable. Are you interested to know what should be included in a PCB fabrication and assembly checklist?

What to Include in a PCB Fabrication and Assembly Checklist?

A PCB fabrication and assembly checklist needs to account for all aspects of manufacturability. The circuit board design software does identify some common design and manufacturability problems. But, there are some electrically functional design choices that may be complex to manufacture. Here is the checklist to prevent the errors that can occur during the assembly of new circuit board designs.
  • GERBER Files: When exporting your circuit designs for manufacturing, it is recommended to recheck the Gerber file format. This is one of the important file formats that describe features of the board including the total number of solder masks, legend, copper layers, silkscreen, and other attributes. Every layer needs a separate Gerber image file. This file is used with photo-plotters, automated optical inspection (AOI) machines, and so on for printing the board image.
  • Pads or Traces Connected to Copper Pour: This is an electrically functional design choice. This means it will not affect the functionality of the circuit board. However, in some cases, this is one common cause of uneven heating during reflow soldering, which may lead to tombstoning. This can be a mistake by a board designer that ultimately affects manufacturability.
  • Centroid File: Centroid file is popularly known as pick and place or XY coordinate file. This file describes the positioning of components including layers, x-y position, rotation, and more.
  • Acid Traps: Traces routed at acute angles (an angle that measures less than 90 degrees) can be difficult when cleaning etching chemicals off the circuit board. This will cause those traces to fabricate at a smaller width than expected.
  • Component Spacing: If connectors and components are not arranged closely in the circuit board layout, then this can cause a problem for pick-and-place machines. A bulky or heavy component may block the next component that needs to be placed on the board.
  • Missing or Thin Solder Mask Between Pads or Holes: The solder mask acts as a dam for holding a solder ball on the desired pad. If the mask is absent, then molten solder can easily flow between nearby pads and create a bridge. This is one common mistake that occurs during circuit board assembly.
  • Overlapping Drill Hits: It is not good practice to place overlapping holes in the circuit board layout as this will cause drill bits to break while manufacturing. Any good quality software will consider this as a design rule violation. Instead, you can define a specific region as a slot in your circuit board design data.
All the mentioned factors will help any PCB fabrication and assembly service provider improve accuracy and build a strong market reputation. Are you planning a PCB assembly for your next project? If yes, then it is important to approach a reliable and certified PCB assembly services provider. With vast industry experience, Accelerated Assemblies has been offering performance-driven and error-free circuit board assemblies to its client across industries.