What are solder preforms?

Solder preforms are manufactured shapes of solid solder. They come in a variety of shapes and sizes, to fit specific requirements. Each preform delivers an exact amount of solder to a joint. Because of this, they are ideal for precision applications. They can be used on their own or in combination with solder paste.

Solder preforms are available in different alloys. Melting points range from about 50°C to over 1000°C. Common shapes are washers, discs, squares, rectangles, and frames. Custom shapes can be manufactured to customer specification.

Do solder preforms include flux?

Most solder preforms can be flux coated or cored. Including flux saves time during production. The flux is activated when the solder is heated. Its action removes the oxides from a surface. Flux also increases the wetting properties of the solder.

The flux coating/coring on the preforms can range from mild to strong. No-clean and solvent-clean varieties are available. If solder preforms are used together with solder paste, the flux type for both should be the same. Different types of flux coatings can come in distinct colors. This helps avoid mixing alloys.

Pre-fluxed preforms are available in various weight percentages. Typical percentages range from 1%-3% of weight. A higher percentage of flux means more residue. Unless the flux is no-clean, residue has to be removed after soldering.

What are the main applications of solder preforms?

Preforms provide uniformity in solder volume, consistency, and adhesion. This makes them the ideal choice for a wide range of applications. These include:

• Household appliances
• Medical equipment
• Aerospace applications
• Lighting products
• Defence applications
• Mobile phones
• Terminal capacitors

What are the advantages of using solder preforms?

• Increased efficiency. Each preform contains a precise quantity of solder. This allows to deliver solder in the right amount to a specific location. Efficiency and productivity are increased.
• Reduced production costs. Using preforms reduces manual processes in assembly. Inspection and clean-up are also simplified. This cuts down costs.
• Allows to solder hard to reach joints. Preforms are ideal for hard to reach joints. Especially in miniaturised components. Compared to solder paste, preforms reduce spillage and inconsistencies.
• Increased stability. Preforms offer increased accuracy compared with hand soldering. This makes them a superior choice for precision applications.
• Optimised features. Preforms use optimised alloys and mechanical design. Each preform will be best suited to certain applications. E.g.,  gold-tin alloys provide hermetic sealing. Low melting point preforms are used to reinforce other joints.

Conro Electronics, as a leading supplier of materials and tools in the electronic manufacturing industry, offers a choice of solder preforms form major manufacturers such as Indium.

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