Different Ways to Choose the Best Low Temperature Soldering Material

Solders are made with a variety of alloys with varying melting temperatures, which typically range from 47 degrees Celsius to 1064 degrees Celsius. Low temperature soldering material is preferred for certain applications that require decreased operational costs. Likewise, it may help reduce materials, labor requirements, and energy, too. Low temperature solder material can eliminate the need to have two SMT steps. Likewise, it can be a wave soldering step to add value while ensuring lower total cost of ownership. Here are ways to choose the best low temperature soldering material:

•    Take note of the main key considerations – Factors like the temperature range of your components, the required thermal properties, and the device’s final operating temperature are crucial when choosing a low temperature soldering material. You also need to consider CTE mismatch and unique properties like lead-free.

•    Explore different types of soldering material – Reputable manufacturers typically offer soldering material in different varieties for various applications like low temperature processing and fine feature printing. Make sure that the product has low drossing rates and low oxides, excellent solderability, high purity, and good wetting. Some soldering materials are lead-free, while others contain tin-lead.

•    Consider the joining application – Low temperature solders may be used in many different joining applications. In cryogenics, for instance, pure indium metal alloy is used in the low temperature soldering material because it can maintain its malleability, even when liquefied gasses experience extreme temperatures. The metal is known for its excellent thermal conductivity and the malleability and softness lets it compensate for a CTE mismatch between various joined surfaces, including any rough surface.

•    A low melting alloy is recommended for thermometers used in food preparation, and in devices used in fire detection. Some electrical fuses may rely on low temperature soldering material to increase their safety.

Advantages and Disadvantages of Using Lead-Bearing Solder Paste

Solder pastes can be made using lead to help electronics manufacturers achieve higher yield and throughput, while lowering their total cost of ownership on many different applications. Lead solder paste can bond metal and electronic components permanently, and it is typically sold as tin-lead (Sn-Pb) solders, which are also known as ‘soft solders’. The product is commercially available, so it is easy to acquire, and the tin concentrations are often between five percent and 70 percent by weight. The higher the tin concentration, the higher the shear and tensile strengths of the solder will be.

Advantages of Using Lead-Bearing Solder Paste
•    The tin in lead-tin solders enhances the wetting property of the alloy, since lead has poor wetting qualities. This way, lead solder pastes have become a better alternative to solid solders, especially in printed circuit board assembly.
•    The melting point of a tin-lead solder paste is at 183 degrees Celsius (361 degrees Fahrenheit), making it safer for certain applications where the temperature is not likely to rise to that level and cause the lead to release toxic fumes.
•    In tin-lead soldering, lead solder paste enables higher and consistent print volume repeatability. Lead solder paste can be handy at the prototyping stage and for hobbyists, too.

Disadvantages of Using Lead-Bearing Solder Paste
If you are buying a lead solder paste, you need to make sure that the tin concentration is enough for the application. There are a few disadvantages to using lead solder paste:
•    It is not recommended for plumbing and food grade applications.
•    Lead-tin solder paste can dissolve gold plating, resulting in brittle intermetallics.
•    Lead solder paste can be poisonous and toxic, so you need to make sure that it is carefully formulated and manufactured. Consider buying lead solder paste only from a reputable and established manufacturer that has years of experience in formulating and making solder pastes in a wide range of alloys.

A Guide about Selective Soldering

Selective soldering can be a cost-effective means to assemble printed circuit boards using through-hole technology. Despite the increasing popularity of surface mount technology, through-hole technology remains preferred in certain applications, although they can be cumbersome. In that case, selective soldering may help simplify the process while ensuring cost-effective and precise results. Selective soldering may be necessary for parts that could get damaged by heat from the reflow oven, which is used in the SMT assembly process.

Types of Selective Soldering Techniques:

•    Manufacturers follow standard assembly processes in selective soldering. Selective aperture tooling over wave solder is a process where tools ignore areas that have been previously soldered by an SMT process. Hence, only the areas that are yet to be soldered are treated in the window or aperture. The PCB assembly is then delivered to the wave soldering equipment to finish the entire process.

•    Another type of selective aperture soldering is the mass selective dip solder fountain. It uses a special tool with apertures that lets the solder to be pumped through, and represents the areas that must be soldered. After soldering, the printed circuit board is delivered to a selective solder fountain and every aspect of the PCB’s selective soldering is conducted simultaneously.

Laser soldering is the latest process in selective soldering and it can import CAD-based layouts to be used in positioning the laser directly to solder any point on a PCB. It eliminates thermal stress while ensuring flexibility and high-quality and consistent solder joints.