Cold Welding

This refers to an unwetted solder joint.

Feature: Gray and dull. Under a microscope the solder joints appear granular.

There are several reasons for this, including improperly setting the reflow oven temperature, too rapid oven speed, placing products too densely into the oven, and solder paste degradation.

Solder Bridging

A short circuit is created when two or more solder joints are connected.

Characteristic: Two pins are joined together.

Solder paste printing failure, solder paste bridging and collapse are the main causes.

False Soldering

This refers to the lack of connection between component pins on PCB and pads. This abnormality most commonly occurs in SMT soldering.

Characteristics: The pad is wrapped in solder, but the pin is not attached.

Main reasons include oxidation, deformations, contamination of pins or pads of components, mismatches in design dimensions, offsets for printing and mounting, inconsistent temperature settings of the furnace, etc.

Standing Piece

Also known as a tombstone.

Characteristics: The component has a warped end and one that is not connected to a circuit.

Causes: An improper product design can lead to uneven heating of both ends of a component, a horizontal plane deviation on the mounting surface, oxidation or contamination of the pin or pad, or an offset printing of the solder paste at one end.

Side Stand

Features: Despite the fact that the components are connected at both ends by soldering, the component's wide side is always vertical.

There are three main causes: loose packaging of components, equipment that is not properly debugged, and the use of a wiping board in the furnace.

Flip

Features: The component with the silkscreen originally facing up is mounted at the bottom. This anomaly will not affect product functionality, but will impact maintenance.

There are several reasons for this, including loose packaging of components, incorrect equipment debugging that leads to flying parts, and strong vibrations during the furnace process.

Solder Beads

Characteristics: Round solder balls are present in the area where the PCB is not welded.

Insufficient solder paste heating time can lead to rewetting.

Pinhole

Characteristics: Pinholes are present on the surface. Rewetting of the welding material, incorrect reflow temperatures, etc. are the main causes.