Conveyor and Magazine Handling Damage on SMT Lines A production line that is set up correctly and still produces defects usually has a handling problem. Conveyors, magazines, board stops and the way boards are stacked between operations all apply loads that the assembly was not designed for, and the resulting…

Conveyor Vibration and Component Movement in Reflow While the solder is molten the components rest in liquid metal. Any movement of the board at that moment moves the parts, and the movement does not have to be large to produce a defect. Where the Vibration Comes From The conveyor chain,…

Magnetics Placement and Layout on Switching PCBs Magnetics are the largest components on most power boards and the ones that cause the most layout trouble. An inductor radiates a magnetic field that couples into any loop it can reach, a transformer couples between its own windings, and both dissipate enough…

Stencil Frame Tension and Print Quality A stencil is a mesh held in tension with an aperture pattern imaged into it. The tension is what makes the stencil gasket against the board and snap away cleanly, and it falls with use. How Tension Is Specified The mesh is tensioned at…

Automotive PCB Quality Requirements in Production An automotive customer buys a board that has to work for the life of a vehicle, and the quality system that supports it is part of the product rather than an administrative layer on top. The requirements are written into the drawings, the process…

Hard Gold Plating for Edge Connectors: A Process Guide An edge connector is the part of the board that will be inserted and withdrawn repeatedly, and it is the one place where a surface finish has to survive mechanical wear rather than only a soldering operation. Hard gold plating is…

Measuring Solder Paste Print Quality on the Line Printing is the step where most solder defects are decided. A deposit that is too small will not form a fillet, one that is too large will bridge, and one that smears will shift a component. Measuring print quality turns those outcomes…

SMT Changeover Verification and First Article A changeover is the moment when a line that was producing one product correctly starts producing another. Most of the escapes that follow a changeover are not random; they come from a step that was skipped because the line looked ready, and a verification…

Solder Pot Maintenance and Alloy Contamination A solder pot is a chemical reactor that nobody thinks of as one. Every board that passes over it dissolves a little copper into the bath and carries a little contamination away, and the alloy changes composition slowly over months of production. The change…

Test Strategy Selection for Low Volume PCB Assembly Choosing how to test a low volume assembly is a different problem from choosing how to test a high volume one, because the fixture cost dominates the calculation and because the product may change before the fixture is worn out. A test…