Functional Test Strategy for Assemblies What Functional Test Is For A functional test powers the assembly and exercises it as the product will be used, checking that the functions work together rather than that each component is present. It is the test that catches the defects that a structural test…

PCB Surface Finish Contact Resistance: The Resistance at the Contact Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding PCB surface finish contact resistance gives you a…

Box Build Assembly and Final Integration Where Box Build Begins Box build is the work that turns a finished board into a finished product: the enclosure, the harness, the connectors, the display, the fasteners and the label. It begins where board level assembly ends and it is where the last…

Rework and Repair of PCB Assemblies Rework or Repair The two words describe different things. Rework is the correction of a board that does not meet specification, restoring it to the intended design, such as replacing a component placed in the wrong orientation. Repair is the restoration of a damaged…

SMT Component Placement Vision Speed: How Fast the Camera Reads Electronics manufacturing has become a discipline of small details. Solder paste volumes, placement accuracy, temperature profiles and inspection limits all add up to the final result. This guide looks at SMT component placement vision speed from the perspective of a…

Solder Mask Defects and Their Causes What the Mask Has to Do The solder mask is the polymer layer that covers the board except at the pads, and it performs three jobs: it prevents solder from bridging between adjacent features during assembly, it protects the conductor from contamination and handling…

Copper Thickness and Current Capacity What Copper Thickness Means Copper thickness is quoted in ounces per square foot, where one ounce refers to a layer of copper weighing one ounce spread over a square foot, which corresponds to a thickness of roughly 35 micrometres. Standard boards use half an ounce…

Underfill and Edge Bonding for Assemblies Why Joints Need Reinforcement A solder joint is the mechanical as well as the electrical connection, and on a large area array package it carries a load that a small ball was never designed to take alone. Thermal cycling makes the package and the…

SMT Reflow Solder Paste Flux Residue: What Is Left Behind Modern electronics depend on boards that are assembled correctly the first time. Every product – a phone, a charger, a medical instrument or an industrial controller – relies on thousands of solder joints that must conduct current for years. This…

Stencil Design for Paste Printing The Stencil Sets the Volume Paste printing is a volumetric process, and the stencil is the tool that defines the volume. For a rectangular aperture the deposit is the area of the aperture multiplied by the foil thickness, so the design of the aperture and…