3D AOI Versus 2D AOI: What Each Method Measures A 3D AOI system projects structured light or a laser line onto the board and reconstructs a height map of every joint, while a 2D AOI system records an image and judges contrast, colour and shape. The distinction sounds technical but…

Interconnect Stress Test: Method and Acceptance Limits The interconnect stress test, usually shortened to IST, is a reliability method that heats a plated through hole with direct current and measures its resistance cycle by cycle. The coupon is its own heater and its own sensor, which is what makes the…

Microvia Plating Reliability: Filling and Cracking A microvia is a small hole, typically 100 micrometres or less in diameter, formed by laser and plated to connect adjacent layers. Its reliability depends on how completely it is filled and how well the plating adheres to the wall and to the target…

Daisy Chain Continuity Coupons for Assembly Reliability A daisy chain coupon is a test vehicle in which the joints of interest are wired in series so that the whole set can be monitored as a single electrical net. Instead of measuring thousands of joints individually, the test watches one resistance…

CAF Resistance Testing: Test Method and Failure Criteria CAF, or conductive anodic filament, is a failure mechanism in which a copper salt filament grows along the resin and glass interface between two conductors under the combined influence of moisture, bias voltage and time. The filament does not form inside a…

Nitrogen Blanket on a Wave Solder Machine: Setup and Limits A nitrogen blanket is an inert atmosphere maintained over the solder pot and along the tunnel of a wave solder machine. Its purpose is to displace oxygen, which otherwise reacts with the molten solder to form oxide and with the…

DI Resin Regeneration: Conductivity and Rinse Quality Resin regeneration is the service step that restores a deionising cylinder to full capacity after it has taken up ions from the process water. Without it the water quality falls away quietly, the rinse tanks lose their margin, and plating faults appear days…

Plating Tank Cleaning: Sludge, Passivation and Refill Tank cleaning is the shutdown work that removes the sludge, the nodules and the chemical film that build up on the walls of a plating tank. It is done between campaigns, when the bath is drained, and it decides whether the next bath…

Route Tab Stress: Cuts, Tabs and Edge Quality Tab stress is the damage left in a panel when the tabs holding a board are cut or broken, and it appears as lifted copper, a cracked laminate or a hairline crack that only shows itself after thermal cycling. The cut itself…

Lamination Vacuum Pump Care: Oil, Vanes and Filters Vacuum pump care is the routine that keeps a press able to pull the air out of a book of prepreg before the resin gels. It sounds like maintenance housekeeping, but the pump is the only thing standing between a sound laminate…