Chapter 11: Inspection and Quality of Solder Joints

11.1 The Role of Quality Control in Soldering

Quality control and inspection are an integral part of making reliable solder joints. Their primary function is the continuous monitoring of all the parameters that contribute to the reliability of the solder connection. The responsibility of the inspection runs through the entire process from incoming inspection of materials and equipment, through in-process control of the process parameters, through final inspection of the product before it leaves the plant. Quality control, however, does not inspect the quality into the product; this must be built into it through careful planning and processing. Quality control merely monitors it to make sure that each one of the steps leading to the reliability of the end product is carried out properly by the various functions within an organization.

Quality-control standards, or workmanship standards, must be carefully compiled for every type of assembly (Sec. 5.2). There are no universal standards possible within such a diversified industry as soldering. Setting up quality standards must be based on knowledge, data, and facts to be useful. Copying standards from other organizations is hazardous, since it may lead to poor reliability and/or inflated costs. Chapter 4 (Designing the Solder Joint) is useful not only when a new assembly is contemplated but also when existing assemblies are scrutinized and workmanship standards are set up. Specific instructions can be found in Chap. 4 for setting up the quality criteria based on design needs.

Final inspection is not the entire function of quality control. In-process...