For so many years, the leaded solder is now the material of choice for PCB manufacturing. However, in recent years, consumers worry about the environmental and health implications of these leaded products, which has increased. These factors led to the European Union’s RoHS directive, which restricted the use of hazardous materials in electronic and electrical equipment, to take effect starting July 2006.
Some nations, unlike the U.S.A, do not have legislation that makes the use of lead within consumer products unlawful. But, some companies are requesting that the electronic device they order be made with lead solder. But again, what type of solder is recommended for usage in the electrical industry? What distinguishes lead free solder from solder that contains lead?
This piece will find answers to all questions relating to this, coupled with providing additional insights regarding lead free solder and leaded solder.
What is Lead Free Solder vs Leaded Solder?
Solder is typically used by electronic makers to attach components to Circuit boards. All solders, whether lead free solder or with lead, have the same purpose. However, different solder techniques are used with different devices as well as use situations.
Lead and tin are the two main ingredients in leaded solder. Leaded solder’s sufficient flowing capability is a benefit. Since its melting point is lower than that of lead free solder, it doesn’t heat up components as much.
Moreover, lead free solder takes on a duller appearance whenever it cools, making it harder for users to spot problems like oxidation. Lead solder also is less expensive and simpler to use compared to lead free solder.
Lead Free Solder
The elimination of lead from electronics manufacturing as well as waste recycling procedures is the primary driver behind manufacturers’ switch to the usage of lead free solder. Alternative materials for soldering centered on the tin metal have rapidly developed over the past 20 years in the field of electronic manufacturing. The components used in this alternate method have characteristics that are different from those of the tin and lead eutectic composition.
Soldiers require performance akin to that of superalloys used in jet engines because they are functional around 80% of the melting temperature. But as things get smaller, the demands for solder junctions keep going up because to the rising stress and density characteristics. Hence, the PCB design that takes into account its melting point that is high and anisotropic features is required for lead free solders.
The Differences Between the Features of Lead and Lead Free Solder
When lead is used in large quantities for a long period of time in consumer goods, negative consequences on the environment, as well as on human health, results. Nowadays, businesses use lead free solder to assist the social responsibility initiatives of environmental protection.
The Melting Point of Lead Free Solder Is Greater than the Lead Solder
Lead-filled solder melts at a temperature of 1830°C, whereas lead free solder melts at 2170°C. The consequences of lead free solder’s greater melting point are as follows:
Compared to lead soldering, which uses a lower temperature, lead free soldering quickly oxidizes its solder. Certain components, such as those with plastic packaging as well as electronic capacitors, are adversely impacted by the higher soldering temperature that lead free solder has.
Components with a low dielectric are more prone to failure because of the high component stress caused by lead-free solder’s high temperature.
Components made with lead free solder feature a number of soldering surfaces. Tin is frequently used by businesses on these surfaces due to its affordability. However this tin produces a thin layer of oxidation present on the exterior that can result in electroplating.
Whether eutectic
Because lead and tin combined to make an eutectic mixture, manufacturers valued this combination. What we mean is that this temperature of the tin and lead alloy is lower than the heats of the two metals separately. Although a eutectic metal pair has not been found, a successful lead free soldering method has been developed by electronic manufacturing industry.
Health Issues
Businesses concerned with environmental preservation cite lead’s harmful nature as this primary justification for switching to lead free soldering. The human body can indeed collect lead even after brief, repeated exposures. Lead can also easily enter the body via your mouth, nose, or skin. Lead-free fuel and paint are now both commonplace. Yet, one of the last remaining products which still uses it is solder.
Workers are especially susceptible to the risks of lead because they can swiftly breathe it in or receive it by contacting contaminated surfaces inside a sector with high lead output. Keep in mind that lead poses a greater risk to youngsters. Thus, everywhere you use lead solder, consider these health issues seriously.
Cost
Compared to lead free solders, lead-filled solder is less expensive. This is due to the fact that lead costs just one-tenth as much as tin, making lead based solder very accessible. Lead free solders can also be made more expensive by some manufacturers who swap out the tin for silver.
Lead Free Solder has Poorer Wettability Compared to Leaded Solder
When the solder joint’s wettability is low, it struggles to meet the needs of tensile strength, shear capacity, and self-regulation ability. As a result, low wettability leads to a high solder joint rejection rate, especially when changes aren’t made to address this weakness.
Physical Characteristics: Lead Free Solder vs Lead Solder
Joint reliability is negatively impacted by lead free solder. Lead free solder is superior to leaded solder in terms of mechanical effect. Moreover, lead-free solder develops surface oxides, the flux impurities, as well as alloy deposits which can result in subpar performance in terms of contact resistance. As a result, the switch in electronic production from the lead to the lead-free does not completely replace the mechanical and electrical components.
Adopting Lead Free Solder
It is crucial to understand that the main distinction between lead free and lead-lead solder is its high tin content. This will help you decide which solder type to use. As a result, you should consider the following factors before making your decision.
Metal dendrite growth
It is significant to notice that the growth processes of tin whisker and metal dendrite differ. Ionic electro-transfer during electrochemistry results in the formation of metal dendrites. Tin whisker, on the contrary, creates shortcuts which further cause circuit failure.
Growing of Tin Whisker
Tin whisker, acting in cylindrical filament or columnar nature, emerges from susceptible areas of the tin oxide covering. There may be shortcuts created by the whisker in-between neighboring pins. Furthermore, it could impact the high-frequency components negatively.
One primary cause of tin whiskers is pressure stress that is present in tin soldering coatings. For example, when there is an excess of metallic alloy Cu6Sn5, it can lead to a number of defects, including build up of pressure stress upon that tin coat, CTE mismatching, as well as pin distortion, which further results in the development of the tin whisker.
Tin whisker, that is more obvious in purest tin, is another effect of high tin alloy concentrations. Fortunately, a number of metal alloys, including Bi and PB, can stop tin whisker formation.
CAF Creation
Another failure brought on by electrochemical processes is a CAF – conducting anodic filament. CAF development is triggered by anode conductive filaments that contains some copper and grows from positive electrodes to negatively charged electrodes. This circuit board is where the procedure takes place.
When the negative and positive electrodes are connected via a short circuit, CAF typically increases. This results in a terrible catastrophe for the production of extremely compressed PCBs. Lead free solder’s high melting point hastens CAF generation.
Tin Pest
Tin pests are a result of impulsive polymorphism stage modification. Normally, uncontaminated tin would turn from white color to grey at temperatures below 130C. Tin pests should ideally pose a risk to reliability. Yet, because the pollution and iron combine, you won’t usually notice it.
Lead-free Solder vs Lead Solder: Which is More Suitable for Use?
Aerospace Corporation conducted a study regarding the use of lead in consumer electronics, which is at odds with the environmental and health facts about leaded electronics. According to this study, there is insufficient evidence to back up the claim that lead used in electronic devices seriously harms both humans and the environment. The quantity of lead which manufacturers really use in electrical rework is so negligible as to not endanger animals.
If lead solder is offered in your local markets, use it. It is simpler to use, its melting point is lower, and results in fewer joint quality issues.
Conclusion
Leaded solder has a lot to offer the electronic manufacturing industry, but change is sweeping in. If they haven’t already, all industries that utilize a lot of solder will most likely switch to the lead free soldering shortly. Aside from that, as many governments implement eco-friendly policies, there could not be enough solder available in the marketplace for hobbyists.
With every change, lead free solder encounters resistance from some people. Yet, in terms of protecting human safety and health, a switch to a much safer approach is unquestionably important.
