Soldering, like any other art has continually evolved over time and embraced various technological changes. The industry has seen the introduction of various technologically-advanced tools such as laser soldering torches, ultrasonic soldering machines and fiber-focus soldering equipment. These all represent leaps in the way basic soldering is carried out with some being safer, faster, cheaper or just better in terms of overall effectiveness. However, these modern soldering equipments have several shortcomings as compared to the conventional soldering irons and torches. These include;
The above mentioned tools are very expensive as compared to buying the regular soldering tools. This is due to various factors that include few manufacturers, costs of production, inadequate materials and research costs. Till a time in future when the advantages can be translated into price, purchasing these tools will continue to be out of bounds for the average soldering enthusiast.
The above-mentioned equipments all utilize highly advanced soldering technology. However, like soldering iron, most of these cannot be used for large scale jobs that require high heat levels and distribution. This carries on the limitation in some current tools. Tools such as welding torches will therefore continue to dominate large-scale metal bonding at least for the foreseeable future.
Lack of sufficient knowledge
A quick internet search on the workings of these new soldering tools returns relatively scarce results as compared to their conventional counterparts. This implies that the knowledge base surrounding the use of these modern tools is relatively shallow and needs to expand before the common person can comfortably use the tools. This is unlike soldering irons and torches that have thousands upon thousands of tutorials for the prospective and current learner. The number of users is also relatively few thus limiting the possibility of accurately weighing the benefits against disadvantages of the tools.
Soldering is perhaps the most widely-used metal bonding method especially for PCBs. This is due to its numerous advantages over other methods that include high precision and neatness. However, the method has various weaknesses against its alternatives. These include:
Risks of lead ingestion
This is a significant health hazard present in the use of solder. When lead is heated, it turns to lead oxide and through naturally occurring can cause serious health problems. Other methods such as wielding and adhesive binding do not make use of lead and are therefore safer as compared to soldering. This disadvantage may however fade with time as regulators eliminate the use of lead-based solder to lead-free ones.
Resin and fume hazards
The elements contained in solder and flux coating in solder cause dangerous fumes once exposed to temperatures above a certain level. Resin for example turns to a wide range of toxic gases that have been known to cause respiratory problems especially if one is exposed consistently to the fumes for a significant period of time.
As compared to methods such as wielding and brazing, soldered joint are probably the joint weakest with those of adhesive bonding. This is evident in plumbing joints that are soldered and require carrying much weight. Soldering can therefore not be used to join heavy items together or those that require high tensile strength.
Soldering is often used to join items of small sizes and on a small scale. This implies that the method may not be applicable in large scale and huge-sized items in a commercial setting. Options such as wielding and brazing are more viable within the commercial setting. In addition to this, soldering will be totally inapplicable for joining large sheets of metal together. This will be due to the time it would take and the relatively poor joint that would result.
Adhesive bonding is one of the non-soldering methods used to join metals. This and compression coupling are among the very few methods that do not make use of molten metal to seal metal joints. The method is also among the easiest since it only involves the application of an adhesive on the surfaces to be joined and then pressing the surfaces together. However, the method has several shortcomings especially as compared to methods that rely on metal to form metallic bonds such as soldering, brazing and welding. The major weaknesses of adhesive bonding include:
Adhesive bonding in metals results in perhaps the weakest joints of any metal joining methods. This implies that the method is limited to situations where the pieces of metal being joined are relatively small and have little to no movement. This is attributable to the fact that the joints are made by a non-metallic substance and will thus be weaker than those between metals. The basic structure of the adhesive also contributes to the weakness.
Poor bond durability
Besides the relatively weak joints formed by adhesive bonding, the joints are also among the poorest in terms of durability. This is perhaps attributable to the behavior and response of the commonly-used adhesives to changes in the environment. Unlike welded or soldered joints, glued joints can be easily affected by humidity, extreme heat, water and extreme cold. This causes the integrity of the joint to deteriorate over time.
Unavailability of quality adhesives
Adhesives are generally made for other purposes other than metal bonding. This means that it is relatively hard to find high quality adhesives for use with metals. The use of the available glue results in the above-mentioned problems in the joints. Once available however, high quality metal adhesive becomes expensive in the long run as compared to alternative methods.