Copper bus bars are commonly coated in tin plating to provide an economical yet conductive surface to transfer current over its lifespan. Given the rise of electric vehicles, power equipment, and IoT devices that rely on current transfers for reliable functioning a conductive coating is necessary.
Electrolytic matte tin plating is the premier choice for copper bus bar plating due to its excellent solderability and corrosion protection, and tin/lead alloy underplates can help limit whisker formation.
Cost
Tin electroplating on copper offers many of the same advantages as silver plating: increased electrical conductivity, ductility and solderability. Tin plating is also more cost-effective and straightforward to acquire compared to other electroplated metals like silver.
Tin plating on copper can come with its own set of drawbacks. Depending on its surroundings, tin may quickly oxidize into an unpleasant dull gray coating that must be removed prior to soldering taking place. Resistance paper may help slow this oxidization process down by keeping these products away from direct sunlight for storage purposes or handling.
Tin is highly ductile but may still be susceptible to stress cracking due to micro-motions and repeated mating/disconnecting of copper components or by bending/stretching during assembly. If not annealed correctly, tin could form brittle surface cracks which impede its performance or even the function of its component.
Tin is not ideal for high temperatures as its crystal structures may form into “Tin Whiskers”, hairlike structures that interfere with electrical conductivity of parts by creating shorts and current arcs that ultimately result in failure in high voltage applications. To address this issue, an alternative is either coating the tin with nickel underplating or co-depositing it with higher percentages of lead or bismuth during depositing.
Tin remains a preferred plating choice for copper bus bars in many industries despite its drawbacks, such as aerospace. Tin-plated copper offers low costs, improved electrical conductivity and solderability properties.
Corrosion & Chemical Resistance
Tin plating (tinning) is the process in which metal objects are coated with an even layer of tin plating to provide corrosion protection and other forms of external damage protection, shielding their base metal and protecting other materials from reacting inadequately with it.
Tin coating provides both superior contact resistance and solderability, along with low levels of human toxicity, making it an excellent choice for use in wet environments and for preventing fretting caused by sulfur-bearing compounds, like tarnish.
Tin’s versatility extends to being applied over copper and other metals to improve their performance, particularly when exposed to higher temperatures – its operating temperature window of 150degC makes tin an attractive alternative to silver plating for these applications.
But it should be remembered that tin does not offer the same level of corrosion protection as silver, and can even oxidate and decrease its ability to conduct electricity, so care must be taken when selecting it for any application. Therefore, before choosing tin for your needs.
To ensure an ideal result in the tin plating process, it is vitally important that the substrate be thoroughly prepared prior to immersion in a bath. This means cleaning it and removing any oil or grease which could affect its adhesion; additionally, baking it prior to electroplating will remove excess hydrogen while also helping prevent intermetallic migration which could diminish the quality of tin deposits.
Valence provides both dull and bright tin plating finishes for various products and applications, including copper bus bars used to transfer electrical power. We are RoHS compliant and can offer RoHS-compliant dull tin plating for critical electronics such as those found within military or aerospace environments.
Valence’s innovative, centralized production line enables us to track every aspect of product quality throughout its entirety – from coil receiving through final inspection and packaging. All data recorded during the production process for every coil of tin plate produced – such as gauge weights, coating weights, tension leveler specs, trimmed widths, pin hole counts, lab tests and more – ensure that each strip meets or surpasses each customer’s requirements.
Electrical Conductivity
Industry relies heavily on tin plating for copper wire and components due to its ductility, corrosion resistance and solderability. Unfortunately, however, over time tin becomes vulnerable to oxidation, leading to weakening and loss of electrical conductivity that compromises functionality of components in products, leading to failure or inefficiency. Luckily this issue can be easily rectified by coating copper with tin so as to avoid further oxidation while maintaining conductivity.
Tin plating involves coating copper wire in a solution of tin salts and water, then running an electrical current through it, which attracts tin ions towards whatever metal object being electroplated, coating it in an even, thin coat of tin. Tin is an extremely versatile material which can produce both dull and shiny metallic looks depending on desired effect; additionally it boasts good conductivity which makes it useful in producing electronic components.
Before beginning tin plating, copper must be thoroughly cleaned to remove any dirt, oil or grease that could interfere with the effectiveness of the plating solution. This step is essential in producing quality final results. After copper has been cleaned and prepared for plating with tin plating, two methods may be utilized: barrel plating or rack plating. Barrel plating involves placing items inside of a large barrel while submerged in plating solution for this step of plating process. Rack plating employs more conventional approaches where items can be directly submerged in plating solution for quick results. Rack plating is an economical yet time-consuming coating method. Racks hold items while passing slowly through a plating solution solution – this process works best with larger or more delicate objects that wouldn’t suit barrel plating.
Solderability
Tin is one of the easiest metals to solder to copper, making tin plating ideal for creating durable connections between copper bus bars and devices they connect. Tin plating also forms an exceptionally strong bond without damaging materials underneath; making this type of plating an ideal way to ensure long-term connections between bus bars and their connected devices.
Tin’s low melting point provides it with superior thermal shock resistance, meaning it can withstand sudden stresses or bumps without suffering damage to its integrity. This property of tin makes it particularly ideal for applications involving high currents or long-term use in harsh environments where other metals might succumb to corrosion.
Before commencing tin plating, the substrate must first be thoroughly cleaned of oil, grease and other surface contaminants that might interfere with forming an effective bond between tin plating and its base material. Once this step is completed, immersing the part into an electrolytic tin bath can then deposit an appropriate coating – then rinsed and dried prior to being assembled into its final form.
Based on your application, tin can either remain matte or be altered with additives to produce a more cosmetic appearance. While adding brightening compounds can add visual appeal, organic compounds added can make soldering easier due to being less likely to burn during production.
For parts that will be exposed to soldering temperatures, a nickel undercoat must be applied prior to tin plating to prevent zinc migration into the tin, compromising solderability and impairing solderability. At AST’s tin plating process we comply with ASTM B678 requirements, testing each coil processed prior to production to ensure solderability.
No matter which coating material is selected to apply the copper plating to your device, it’s crucial that a reliable and experienced company be selected as your partner in achieving optimal results. At AST we provide bright and matte tin plating on coil, as well as various other finishes. Our professional team will assist with selecting the ideal coating based on factors like corrosion & chemical resistance, electrical conductivity and solderability – contact us now and start!
