Which of the following is included in the visual inspection criteria for solder joints?

The inclusion of the shape, size, and cleanliness of solder joints in the visual inspection criteria is crucial because these aspects directly relate to the reliability and performance of the electrical connections. The shape of the joint can indicate the quality of the soldering process; for instance, a well-formed joint should have a smooth, even surface that is properly shaped which helps ensure a strong mechanical and electrical connection. Size matters because insufficient solder can lead to weak connections, while excessive size may cause bridges or unintended connections between pads. Cleanliness is essential as contaminants on the surfaces can interfere with solder adhesion, potentially leading to failure of the joint over time.

In contrast, the presence of excess solder may be a concern but is just one specific aspect rather than a broader evaluation of joint quality. The temperature of the soldering process is more related to the technique used rather than the inspection criteria themselves. Similarly, adequate soldering iron calibration is an important maintenance factor in achieving good solder joints but does not fall under the visual inspection criteria directly. Visual inspections focus primarily on observable characteristics that can affect the effectiveness and longevity of the solder joints.