Mastering PCB Soldering: Types, Techniques, and Key Resources

Apr 26,2021

Soldering is an important step in PCB manufacturing and assembly. It is commonly known as the PCB soldering process. Soldering is used in PCB fabrication to fix the mounted components on the printed circuit boards. In this process, the active end of the mounted component is fixed on the PCB board while making interconnections with other components mounted on the PCB. In this process, the molten material is applied to the connecting points of various components and allowed to solidify to form a durable joint. However, the PCB soldering process is not as easy as it sounds. There are different types of PCB soldering processes adopted based on the operational requirements of the PCBs. Also, the resources chosen for PCB soldering differ based on the types of soldering. This post introduces you to these different types of soldering and the essential resources required to complete them.

Types of PCB Soldering Processes

There are two common types of soldering processes adopted in industrial PCB fabrication, as listed below.

• Soft Soldering:

  Soft soldering is the type of soldering performed for soldering low-load components. This process is done at a low temperature between 90°C to 450°C. The soldering materials used for soft soldering are metal alloys such as tin-zinc alloy, zinc-aluminum, cadmium-silver, etc. This process offers weak bonding between the component and the PCB. However, it is suitable for repairing broken solder joints. It cannot be adopted for PCBs where high reliability is required, but the thermal stresses caused by this process can fix the broken solder joints.

• Hard Soldering:

  Hard soldering is a more reliable and popular type of soldering. In this type of PCB soldering process, the space filler material is applied between the component and the board. In this type of soldering, brass or silver are used as space filler materials and application temperature remains higher than 450°C. This type of soldering offers a stronger bond between the soldered surfaces. Hard soldering is further categorized into the following two types.

  • Silver Soldering:

    Silver soldering is the hard soldering technique mostly used for solder maintenance. Alloys of silver are used as filler material in this process. If this method of soldering is adopted, a blowtorch is required to spread the molten silver alloy in the soldering space.

  • Brazing:

    Brazing slightly differs from the above-mentioned types of soldering. This hard soldering method requires heating of the surface material and space-filling material opposite each other. The bonding takes place due to the fusion of both the molten materials. This process is performed at a very high temperature than silver hard soldering. However, brazing is considered a highly reliable method of PCB soldering.

Essential Resources for PCB Soldering Process

The above-mentioned PCB soldering processes require the following resources to complete the process.

• Space Filler Material/ Solder:

  Space filler or solder materials are commonly metal alloys. These alloys differ based on the soldering requirements and industrial standards followed. The following are the types of solder materials used by PCB contract manufacturers.

  • Lead-Based Solder:

    Lead-based solder materials like tin-lead alloy is used for soldering. This type of solder material offers high tensile strength and shear strength. Ideally, this type of solder is used for soft soldering.

  • Lead-Free Solder:

    Lead-free solder materials like silver, bismuth, indium, etc are used in the RoHS compliant PCBs. Lead is a toxic material and according to the RoHS guidelines and EU standards, lead-free soldering is adopted.

• Solder Gun:

  A solder gun is equipment used to inject the solder space filler material. The solder guns generate high voltage to melt the solder material. Then the molten material is deposited on the surface. If the solder material does not drip easily then blowtorch is used to enhance the dripping properties of the molten space filling material.

• Solder Flux:

  Solder flux is essential as it removes rust from the surface, blocks the entrance of air, and enhances the quality of soldering by improving the dripping properties of solder material. If the flux is used in the soldering, the process is called flux core soldering.

• Solder Paste:

  Solder paste is applied to prepare the surface for soldering. It enhances the interaction between the component surface and the molder filler material.

Now that the types and essential resources of PCB soldering processes are discussed, it is important to choose the right PCB manufacturers too. For PCB manufacturing and soldering services, you must partner with the trusted suppliers like Creative Hi-Tech. The company offers high-quality lead-based and RoHS compliant lead-free soldering services under contract PCB manufacturing services.

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