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What is the Melting Point of Solder?

Solder is an important element commonly used in the electronic industry. The uses of solder can’t be overemphasized as this element plays vital roles in the production of electronic devices. However, this element has its own melting point. This article seeks to shed more light on the melting point of solder.

What is Solder?

Solder is a metal alloy that comprises tin and lead. Solders help to join two or more components together. This metal alloy consists of several alloy compositions with melting points as high as 400°C. Also, the melting points could be as low as 90 degree Celsius. Solder helps to create huge bonds of permanent nature like copper joints in PCBs.

The Melting Point of Solder

Temperature determines the melting point of any material. The temperature here refers to the temperature at which solid changes to liquid. Also, this temperature specifies the type of materials to use in a real world application. Solders melt and bound electrical components. The melting point of solder determines the choice of solder alloy for an application.

For instance, if the device will function under high temperature, the solder must have a higher melting point than the operating temperature. This means that the operational environment of a device determines the melting point of solder.

The right melting point of solder is about 250 degree Celsius. This specifies a good quality solder metal. Also, you can determine the quality of a solder through its high conductivity and low flux content. Solder comprises an alloy of lead and tin. This tin can be 60% while the lead is 40%. Also, this solder has a varying melting temperature range. However, it will start melting at 361.4 °F. Also, it will turn to a full liquid at 375.8 degrees Fahrenheit.

A solder with 50% of tin and 50% of lead has a melting range between 361 °F and 421 °F. The melting point of a silver solder is 1145 °F. This solder melts until it gets to 1145 °F. Also, Zinc/aluminum solder has high melting point of 719.6 °F. A 70/30 lead-tin grade solder features a melting temperature of 255°C.  Therefore, the melting point of solder depends on its composition and type.

Categories of Solder

 Another factor that determines the melting point of solder is its formulation. Solders can be Eutectic and non-eutectic.

Eutectic solder

This solder can easily melt. Therefore, eutectic solder describes a metal alloy that melts at a single temperature. Also, after cooling, this solder solidifies at a single temperature. Furthermore, some manufacturing processes require this capability.

Non-eutectic solder

This metal alloy can’t melt at a single temperature. Also, this type of solder has a melting range. Eutectic solder starts melting at a particular temperature. Then it continues melting as the temperature rises.  Also, the melting stops when the solder reaches the final temperature and the alloy is liquid.

The melting range is the difference between the melting finish and the melting start temperatures. Some solders’ melting range is 75 degree Celsius. The melting range can be as low as 32 degree Celsius.

Which is the Ideal Solder to Use?

The choice of a solder alloy depends on several factors. However, the two major factors are:

  • Subsequent thermal processes
  • Solder melting point of the process

A manufacturer may demand a high temperature solder since there will be subsequent thermal processes. Also, the high temperature solder gives him the freedom to carry out more than one thermal process. However, a low temperature solder might be necessary when the components involved are thermally sensitive. These components can damage when exposed to high temperatures.

Types of Soldering

Soldering is a process that involves connecting different types of metals by melting solder. During soldering, two or more components are joined together. To achieve soldering, engineers melt the solder by using heat generated by iron. There are different types of soldering which include:

Hard soldering

In this soldering process, the engineer uses brass or silver. Also, this type of soldering creates a strong connection. To maintain a strong connection, this soldering demands a blowtorch. This helps to increase temperature and melts the base metal.

Soft soldering

Soft soldering features the lowest filler metal melting point. Also, this soldering type utilizes low temperatures. However, it isn’t ideal for mechanical load-bearing applications. This is because it isn’t ideal for use in extremely high temperatures.  Therefore, it is widely used in plumbing and electronics.

Soft soldering connects electronic components in PCBs. The lower temperature established a strong joint.

Brazing

This is the third type of soldering that uses metal with a higher melting point. The melting point of this soldering is higher than soft and hard soldering. Also, the bonded metal is heated opposite to the melted down metal. Brazing requires to sufficiently heat the material to achieve the best result.

Uses of Soldering

Soldering is of great importance in several applications. The application determines the composition of solder.  Below are the uses of soldering:

Electronic components

Soldering is widely used in electronic devices. It helps to create electrical flow. Also, soldering guarantees you electrical flow in residential or commercial wiring. Therefore, it is useful in merging wires to terminals in an electrical device.

Plumbing

Solders are of great importance when it comes to plumbing. You can use solder to join copper plumbing pipes. The lead-free solder is ideal for this application.

Auto repair

In this application, solder tightens the joints. Also, it smoothens the surfaces of auto parts. Although solder can’t fix engines, it can fill irregular cavities and tighten joints.

Printed circuit boards

In printed circuit boards, solders help to connect electrical components. Soft soldering helps to attach small components on PCBs. It helps to fix the component leads with the copper tracks. This ensures they are electrically connected.

What are Solder Blends?

Solder comprises three major materials which are flux, tin, and lead. However, there are several diversifications of solder based on the relative ratio of these materials. Furthermore, there are some additives and metals that you can add to solder. This helps to strengthen the conductivity of solder.

  • Copper enhances the wetting characteristics of solder. Also, it minimizes the melting point in any molten condition.
  • Antimony increases the mechanical strength of solder.
  • Nickel prevents the Under Bump Metalization layer (UMB) from any dissolution.
  • Silver provides great mechanical strength. However, it provides lower ductility than lead.

Conclusion

Solders are in several forms and shapes. The melting point of a solder determines a lot. The solder melting characteristics are a critical factor while selecting a solder alloy. However, there are other factors that determine the selection of the alloy.