Solder Splash: 5 Rules to Stop Stray Solder A solder splash is any stray alloy that lands on the board surface instead of inside the joint. It appears as small balls, flat beads or fine droplets scattered around a footprint, and it is one of the defects that assembly houses…

Cold Joint: 5 Rules for Complete Solder Melting A cold joint is a solder connection that solidified before the alloy and the surfaces reached the temperature needed to form a proper bond. It is recognised by a dull, grainy surface that contrasts with the bright, smooth fillet of a good…

Stencil Cleaner: 5 Rules for Under Stencil Wipe A stencil cleaner does two jobs at once. It removes the solder paste residue that builds on the underside of the foil, and it clears the paste left inside the apertures so that the next print starts from a known state. Both…

Feeder Jam: 5 Rules for Tape Feed Reliability A feeder jam is the moment the tape stops advancing while the placement machine keeps running its cycle. The nozzle closes on empty tape, the machine reports a pick error, and the line either stops or skips the reference. Either way, the…

Solder Bridge: 5 Rules to Stop Bridging A solder bridge is a connection where there should be none, formed when enough molten alloy joins two adjacent pads or pins to make an electrical path. On a fine pitch assembly it is the defect that ends the panel, because a bridge…

Wrong Part: 5 Rules for Reel and Program Control A wrong part is a component of the correct package but the wrong value or the wrong internal specification, and it is one of the few defects that can pass every optical check on the line. A different value in the…

Missing Part: 5 Rules for Placement Verification A missing part is an empty footprint on a finished assembly, and it usually reaches the customer because every check between the machine and the shipping box assumed that something else would catch it. The placement machine fed a component, the inspection looked…

Tombstone: 5 Rules to Stop Chip Lifting A tombstone is the defect where a two terminal chip component stands up on one end after reflow, held vertically by the fillet that formed under it. The name comes from the shape. It happens because the two ends of the part do…

Inkjet Legend: 5 Rules for PCB Markings An inkjet legend is the printed marking on the surface of a circuit board, applied by a print head that deposits drops of ink instead of pushing ink through a screen. It replaces the traditional silkscreen step for anything that does not need…

Deaeration: 5 Rules for Solder Paste Handling Deaeration is the removal of the air that gets into solder paste during storage, transfer and printing. On an SMT line the word usually covers the steps that stop that air from reaching the stencil at all, because air in the paste becomes…