Soldering seems like a modern technique, but it is an ancient practice that has evolved over thousands of years. Its purpose has always been the same- to join two similar or dissimilar metals by using a solder material that melts below the temperature of the joining metals. What has changed is the number of solder alloys and the way each of them is suitable for a particular solder task. From the solder wire, sticks and rods, to the solder flux, SMD paste no clean, and solder flux paste, we at Bajaj Insulation Co. have numerous options for each application. In this blog, we will uncover the types of solder and how to choose for each application.
Common Solder Types and Their Applications
● Tin-Lead Solder (Sn-Pb)
These are general-purpose alloys that melt at low temperatures. Used in electronics assembly, wire terminations, smaller electrical goods and PCB works. These are used where regulations allow for the use of lead. The common compositions are: 10/90, 15/85, 20/80, 25/75, 30/70, 35/65, 40/60, 45/55, 50/50, 55/45, 60/40 and 63/37.
● Lead-free Solder
The Tin-Copper (Sn-Cu) and Tin–Silver–Copper (Sn/Ag/Cu) alloys are lead-free because lead is harmful to human health and toxic to our environment. Being eco-friendly, these match the standards of European norms and RoHS. Common compositions for tin-copper solders are 99.3/0.7 and 99/1, while for tin-silver-copper are 99/0.3/0.7 and 96.5/3/0.5. The suitable applications are consumer electronics, PCB assembly, and components that can withstand slightly higher temperatures.
● Antimonial and Bismuth-Based Solders
These are harder alloys with higher melting points. However, they are economical and less costly than the silver alloys. These can be used in mechanical joints and industrial applications where heat tolerance is high.
Factors That Determine Suitable Solder
1. Application
Each application has its own needs. Factors such as temperature tolerance, PCB layout, and the size of the solderable area determine the choice of alloy. Artificial jewellery often uses low-cost, high-lead solder because the joints are later polished and hidden. Lead batteries follow a similar approach, using medium to low-grade solder with higher lead content to keep costs in check and meet their temperature range. High-lead solders are more economical, while tin-rich grades are costlier. Alloys such as 60/40 and 63/37 provide a bright finish and are chosen when a clean visual result is important.
2. Alloy Composition
The ratio of tin, lead, copper, silver, antimony, or bismuth in the solder alloys changes the melting range, mechanical strength, and cost. By choosing the correct B.I.C solder wire, stick/rods, you can ensure that the soldered joint performs reliably throughout the product’s life.
3. Melting Temperature
Temperature is the fundamental factor in soldering. For heat sensitive materials like semiconductors, intricate electronics and plastic-covered parts, using an alloy with a low melting temperature is necessary. For mechanical joints, power connectors, transformer terminals, or industrial heating elements, harder alloys with higher melting temperatures are suitable.
4. Flux Type
Flux removes the oxidation layer and improves the flow of material and wetting of the surface. The variety of the flux-type solder wire is rosin core, SMD paste no clean, urea cored, etc. These have the quality of leaving low or no residue, producing low smoke and they are non-conductive, hence eliminating the problem of electrical faults. B.I.C Solder Flux and B.I.C Solder Flux Paste are applicable in a wide range of soldering operations from temperature-sensitive mobile-phone to larger industrial joints where proper wetting and controlled flow are required.
Conclusion
Bajaj Insulation Co. makes solder wires, sticks, No clean solder flux and solder flux paste, which are used in mechanical joining, electronics manufacturing, semiconductor assembly, thermal control applications, and thin-film processes. These uses represent only a part of our range. To understand how our materials can support your work, explore these common applications and reach out to us for further guidance.
