Manufacturing Instructions
Legal and technical specifications included on the board design drawing communicate the materials, tolerances, and inspection criteria required for physical board production. These fabrication drawing notes define the layer stack-up, dielectric thickness, drill sizes, and surface finishes that the manufacturer must follow. This block of text acts as the primary contract between the designer and the fabricator, taking precedence over digital Gerber files in the event of a discrepancy.
Quality Control
Quality requirements and acceptable defect limits are established through these documented guidelines. The fabrication drawing notes specify the IPC performance class, such as Class 2 or Class 3, to dictate the rigor of quality control inspections and destructive testing. They also define the specific board thickness tolerances, copper weights, and impedance control targets that must be validated before batch release.
Without these clear notes, the fabricator may make assumptions about laminate selection or plating thickness that lead to non-conforming boards. It is therefore standard practice to include detailed instructions regarding solder mask color, silk screen requirements, and peel-off mask specifications in this section.
Compliance Verification
Regulatory and environmental compliance standards are also enforced by these drawings. The notes mandate compliance with RoHS or REACH directives to ensure the materials do not contain restricted hazardous substances. By verifying these notes during incoming quality inspection, the assembly partner ensures the incoming bare boards are fully compatible with their manufacturing process.
