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…

BGA Rework and Reballing Why BGA Rework Is Different An area array package cannot be soldered with an iron. The joints are underneath the body, so the only way to make or break them is to heat the whole package until the alloy melts, using a machine that controls the…

In-Circuit Test and Flying Probe Compared What Structural Test Does Structural test checks the assembly itself rather than the function of the product. It confirms that the components are present, of the right value and in the right place, and that the connections between them are intact. Because it does…

SMT Reflow Solder Joint Life Prediction: Guessing How Long It Lasts 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.…