The Defective Solder Joints in SMT Assembly

1.    Solder connection. For SMT assembly process, solder connection is also known as tin bridge. Parts that should not be connected, such as between component ends, between adjacent solder joints of components, and between solder joints and adjacent wires, vias, etc., are soldered together, SMT assembly processing industry refers to it as solder connection.
2.    Stand tombstone, also known as the Manhattan phenomenon, refers to a piece of component with two solder ends, after reflow soldering, one of the solder ends leaves the surface of the solder pad and the entire component is tilted and upright. The SMT assembly industry calls it stand tombstone.
3.    Side standing. The phenomenon of contact between the side of the chip component and the PCB pad. The SMT industry calls it side standing.
4.    Offset. The component moves in a horizontal position, causing the solder joint or pin to not be directly attached to the PCB pad.
5.    Highlight. The phenomenon of a chip component facing the front of the PCB and the bottom facing upwards.
6.    Tin beads. Tiny bead-like solder that is attached to the chip component or scattered near the solder joint after reflow soldering.
7.    Cold soldering. Incomplete reflow phenomenon, where the solder does not reach its melting point temperature or the soldering heat is insufficient, causing it to solidify before wetting and flowing, without forming any metal alloy layer at all, resulting in the solder being completely or partially amorphous and simply accumulating on the surface of the soldered metal.
8.    Core suction. Solder crawls up from the solder pad along the pins and between the pins and the chip body, resulting in insufficient soldering or empty soldering at the solder joint.
9.    Reverse. It refers to the polarity direction of a component with polarity that is not consistent with the actual required direction after soldering.
10.    Bubbles. The gas in the solder fails to escape in a timely manner before solidification, resulting in the formation of voids inside the solder joint.
11.     Pinhole. A small pin-shaped hole formed on the surface of a solder joint.
12.     Cracks. The phenomenon of solder joints cracking due to mechanical or internal stress.
13.     Solder tip. There is solder protruding outward in the shape of needles or thorns at the soldering point.
14.    Excessive solder. The solder at the soldering site is much higher than the normal demand, resulting in unclear visibility of the soldered part or the formation of accumulated balls of solder.
15.    Open soldering. All pins/solder ends of components are detached or deviated from their corresponding solder pads without proper soldering.
16.    White spot. A phenomenon that occurs inside a laminated substrate, where glass fibers separate from the resin at the vertical and horizontal intersections. This phenomenon manifests as discrete white spots or "cross shaped" beneath the surface of the substrate, usually related to stress formed by heat.
17.    Grey soldering. Due to high soldering temperature, excessive volatilization of soldering flux, and repeated soldering, the surface of the soldering area is gray, the solder crystal is loose, porous, and slag like.