Nozzle Selection for Pick and Place The Nozzle Is the Interface The nozzle is the only part of a placement machine that touches the product, and it decides whether the component is picked reliably, held in the right orientation and placed without damage. A machine with an excellent vision system…

SMT Reflow Solder Joint Inspection Criteria: The Rules for a Good Joint Buyers and engineers often focus on the finished product and forget the production line behind it. In practice, most field failures can be traced back to process decisions made during assembly. Understanding SMT reflow solder joint inspection criteria…

Paste Print Defects and Their Causes The Print Is the Process Paste printing is the step that places the material, and every defect it produces is carried through reflow into the joint. A print defect cannot be corrected later, because the oven will melt whatever is on the pad. This…

Cold Solder Joints and Poor Wetting Two Different Defects A cold joint and a poorly wetted joint are often described as one problem, and they are not. A cold joint has not reached a temperature sufficient to melt the alloy properly, so the solder is grainy, dull and mechanically weak.…

PCB Laminate Dielectric Loss Tangent: The Energy the Board Absorbs 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…

Voiding in Solder Joints What a Void Is A void is a pocket of gas trapped inside a solder joint. It forms because the flux volatilises during reflow, because the surfaces release moisture or contamination, or because air is entrapped in the paste when it is printed or dispensed. The…

SMT Stencil Frame Type: The Holder for the Foil 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 article…

Tombstoning and Placement Defects What Tombstoning Looks Like A tombstoned component stands on one end, with one termination soldered to its pad and the other lifted clear, like a headstone. It is common on small passive components, where the mass is low and the imbalance is easy to create, and…

PCB Copper Trace Length Matching: Keeping the Traces Equal 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. The same…

Solder Bridging: Causes and Cures What a Bridge Is A bridge is a continuous connection of solder between two features that should be isolated. It can form between adjacent pads, between the pins of a connector, between a component termination and a nearby track, or between a ball and its…