AWS GHSP:2014

This guideline will serve as a primer for students, instructors, process engineers, and technical managers involved with manufacturing processes that require hand soldering practices. Instructors and students would consider this guideline as a reference text to instruction manuals, work control procedures, and drawings. Process engineers and technical managers will find this guideline to also be an excellent resource for troubleshooting hand soldering processes. A complementary document to the Soldering Handbook, this guideline will be organized to allow quick access to hand soldering knowledge for application to process development and shop floor instructions
Scope : 1.1 Hand Soldering. The terms hand soldering and manual soldering refer to soldering operations performed by an operator. Traditional images associated with hand soldering include the assembly of electronic components [see Figure 1.1(A)], or the joining of pipes for plumbing and similar applications [see Figure 1.1(B)]. The extent to which an operator participates in the soldering process can be to various degrees. In a fully manual process, the operator is responsible for the following steps: (1) Positioning the individual parts; (2) applying the heat source; (3) applying the flux; (4) introducing the filler metal; (5) cleaning the finished assembly; and (6) inspecting the finished joint. Semiautomated soldering processes allow machines to perform one or several of the above steps. For example, the positioning of parts can be performed by a robot prior to the soldering step. In the case of (fully) automated soldering processes, the operator is typically responsible only for loading the individual parts into the â??frontâ? of the assembly line and for removing the finished assemblies from the â??backâ? of the line. The electronics industry uses automated furnace or wave soldering processes to maximize production volumes, thereby minimizing the costs of manufacturing printed wiring assemblies. At first glance, the hand soldering of a single joint at a time appears to contradict the precepts for cost-effective manufacturing: high volume (many joints made at a time) and statistical process controls that are optimized through automation. Yet, hand soldering is cost effective for a number of applications. There are companies that concentrate on low-volume, short production runs where the capital and maintenance costs of machines simply are not justifiable. In other applications, an operator provides a flexibility that is required to address â??unusualâ? part configurations that would otherwise require elaborate fixturing and/or equipment modifications if performed by a machine. Lastly, hand soldering is the only method to perform field repairs where equipment and operator portability are essential. It is not the case that the quality or â??workmanshipâ? of hand-soldered joints is nominally below par of that produced by machine soldering. Rather, the quality of hand soldered joints tends to be more variable than of automated processes; it depends on the operatorâ??s training and skill. In terms of solder joint quality, an important advantage of hand soldering is that the operator inspects each joint as it is being completed, thereby providing the opportunity to identify defects (e.g., poor solderability) before a large number of parts have been processed. This attribute minimizes costly rework activities or scrapped material, particularly during the assembly of high-value, high-reliability products in which a single solder joint defect would have unacceptable consequences. It is important that design and process engineers, as well as operators, understand the fundamental materials engineering that underscore soldering technology. Foremost, there are the wettability and solderability properties that are basic to the creation of a solder joint. Secondly, the successful hand soldering operation (or any soldering operation) is dependent upon a heating process. It will be observed that these factorsâ??wettability, solderability, and heating processâ??are integral to the development of a successful hand soldering operation.