AOI Programming: Design Rules and Process Limits Automated optical inspection only earns its place if it finds the defects that matter without flooding the line with calls that are not defects. The difference between a useful program and an expensive one is almost entirely in the programming, and the work…

PCB Shop Humidity Training: From Prototype to Volume Production 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 PCB shop humidity training from the perspective of a PCBA factory…

PCB Shop Humidity Maintenance: What Matters on the Production Line 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…

PCB Shop Humidity Defects: From Prototype to Volume Production 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 PCB shop humidity defects from the perspective of a PCBA factory…

Placement Program Optimization and Cycle Time A placement program decides the order in which the parts are placed and the nozzles that are used, and two programs for the same board can differ in cycle time without any difference in the hardware. The optimization is a scheduling problem with constraints.…

Print Alignment Verification and Offset Control The paste has to land on the pad, and the printer aligns the stencil to the board using fiducials. A small offset reduces the solderable area and a larger one puts paste on the mask, and the two consequences are different. How the Printer…

Glass Transition Temperature and Its Use in PCB A laminate has a temperature at which its mechanical behaviour changes, and the change is what the glass transition temperature describes. Above it the material expands faster and becomes softer, which is the condition the assembly processes create. What the Transition Is…

Surface Finish Thermal Aging A surface finish is not a passive coating. It is a thin layer of metal with its own diffusion behaviour, and it changes from the moment it is applied. Thermal aging is the process by which that change becomes a soldering problem, and it happens during…

Solder Mask Colour and Its Process Effect Solder mask is supplied in a range of colours, and the colour is a pigment rather than a property. The pigment changes the cure, the resolution and the inspection contrast, which is why a colour change is a process change. What the Colour…

Reflow Conveyor Vibration: Causes, Symptoms and Fixes Conveyor vibration is one of the few reflow faults that leaves no trace in the profile data. The thermocouples read correctly, the zones hold their setpoints, and the oven passes its daily check, yet boards come out with shifted chip components, tombstoned passives…