Thermal Profiler Setup: Getting a True Reflow Reading A thermal profiler records the temperature history that a board actually experiences, and the value of that record depends entirely on how the sensors were attached. A reading taken beside a pad instead of on it, or routed so that heat drains…

Laminate Moisture: 4 Checks Before the Press Cycle Laminate moisture is the water that a core or a sheet of prepreg holds inside it, and it has no place in a press cycle. When the stack is heated, that water turns to steam, and the steam has to go somewhere:…

Pogo Pin Fixtures: Contact Resistance and Maintenance A pogo pin is a spring loaded contact that presses a probe tip against a test point, and a bed of nails fixture holds hundreds of them in a plate that is lowered onto the board. Every measurement the fixture makes passes through…

Busbar Contact Resistance: 4 Checks for Even Plating Current Current leaves the rectifier through copper busbars, crosses a series of bolted and clamped joints, and enters the tank through the rack hooks. Every one of those interfaces has a resistance, and the sum of them decides how much of the…

Solder Mask Ink Viscosity: 4 Checks Before Screen Printing Ink viscosity is the property that decides how a solder mask behaves as it passes through the screen. Too thick and the ink will not flow into the openings; too thin and it bleeds under the emulsion, closing the fine clearances…

Poka Yoke in PCB Assembly: 7 Devices That Stop Mistakes A poka yoke is a device or a rule that makes a mistake impossible to commit, or impossible to pass on unnoticed. The term comes from Japanese manufacturing practice, and on a PCB assembly line the idea is simple: rather…

Solder Mask Spray Coating: 6 Rules for Even Films Solder mask spray coating builds the protective film by atomizing liquid ink and depositing it on the panel surface, layer by layer, instead of pushing it through a screen. It is chosen where the copper is tall, the features are dense…

Solder Mask Jetting: Inkjet Printing for Fine Features Solder mask jetting is the deposition of solder mask ink directly onto the board through an inkjet print head, with no screen, no film and no development step. The head writes the pattern from the CAD data, so a change to a…

Etchant Analysis: Keeping Copper Etch Chemistry in Balance Etchant analysis is the routine measurement of the chemistry that dissolves copper, and it exists because the etch rate drifts as copper accumulates and the oxidising power of the bath falls. A bath that is not analysed etches slowly at the start…

Steam Aging for Solderability Testing: 7 Process Rules Steam aging is a preconditioning step rather than a test in itself. It exposes a test coupon to hot, condensing moisture for a defined period so that the surface oxide grows in hours to something like the condition a board would reach…