2. Manufacturing Specifications PCB + PCBA Process
Quality must be engineered into the tolerances. The physical attributes of a PCB often establish the fundamental constraints for the entire assembly process.
Manufacturing Specifications define the essential boundaries for material properties, trace widths, and solder mask requirements. When these parameters are left undefined, it allows suppliers to make arbitrary choices, which introduces unpredictable variability into the final build.
- 2.1 Material Science, Stackups and Via Architecture
A printed circuit board defined solely by Gerber files is an incomplete specification. Without an explicitly documented material and stackup definition, fabrication houses may default to the lowest-cost laminate that meets the bare minimum IPC class....
- 2.2 Surface Finishes and Panelization Strategy
The physical and electrical interface between the component and the PCB is dictated by two critical factors: the surface flatness (planarity) of the finish and the mechanical rigidity of the panelized array. A poorly selected surface finish increases...
- 2.3 Land Patterns, Spacing and Polarity
A component footprint is more than just a drawing; it's a carefully engineered prediction of how molten solder will behave under the physical forces of surface tension during reflow. Relying solely on generic manufacturer datasheets for land patterns...
- 2.4 Process Specs: Alloys, Stencils and Chemistry
Soldering is more than just applying conductive glue; it's a complex metallurgical process governed by phase changes, fluid dynamics, and surface tension. If the foundational chemistry isn't properly controlled, the solder joint will eventually fail,...
- 2.5 Workmanship and Acceptance Criteria
Quality cannot be negotiated after the solder has cooled. Subjective terms like "good enough" or "looks neat" are insufficient and can lead to disputes between the EMS and the client.