What is the difference between solder paste and flux?

What is the difference between solder paste and flux?

Nowadays, many people are confused about the two concepts of solder paste and flux and think they are the same. But in fact, flux is a general term used to increase the reliability of solder and the object to be welded during soldering. The main functions are the wetting effect, removal of oxidation, auxiliary heat conduction, metal surface tension reduction, solder joints' appearance, etc. The two are not the same substance. The following is an introduction to the concept of solder paste and flux.

What is flux?

Flux is a substance that assists welding. The main components of the liquid are isopropyl alcohol, rosin, organic acid, etc., which are used for welding parts of electronic circuit boards. It is used to clean the surface oxide layer of the metal at the welding site and help the solder flow and expand.
Most users favor the lead-free, no-clean flux because of its low smoke, fast speed, and solid inclination.
Product advantages:
1) Acid-free solder paste, made of acid-free flux, semi-solid and not easy to tilt;
2) Make the welding firm reliable;
3) Anti-oxidation flux, which has an anti-oxidation effect on the soldering iron of the gold-copper composite substrate;
4) Lead-free environmental protection, non-conductive, low odor, no cleaning;
5) The main control chip is drag-soldered, easy to tin, and has good fluidity;
6) Wide applications suitable for sensors, motors, electronic components, BGA chip value balls, etc.

What is solder paste?

Solder paste is used for SMD soldering of circuit boards. It is a product used to bond different parts of metal alloys to each other. It is also an upgraded substitute for the flux and soldering processes, with a high degree of automation and high welding precision. The main components include metal powder, rosin, organic acid, thixotropic agent, and active agent.
There are many solder products, including solder paste, solder wire, and solder balls.

1. Solder paste

According to the level of soldering temperature, solder paste is divided into a low temperature, medium-temperature, and high-temperature solder paste. Among them, the melting point of low-temperature solder paste is 138°C, and the melting point of medium-temperature solder paste is 183°C. Suitable for daily maintenance and use, the solder joints are firm, plump, and bright. One-piece open cover design, more convenient to use, better storage effect! No virtual welding, less residue, and strong adhesion. The solder paste has built-in unique ingredients to prevent bubbles from being generated during the soldering process and affect the soldering effect. You can choose the appropriate solder paste according to its melting point and the weight of the solder paste.
Product features:
1) Diversified compatibility, suitable for various welding environments, with high compatibility.
2) Original authentic, stable, and rigorous production process, giving you good quality.
3) Environmentally friendly products.
4) Use solder paste with corresponding melting point temperature for soldering to avoid high-temperature reflow of solder, which will cause damage to components and PCB.
5) The viscosity is moderate, there is basically no collapse, and the sheet-like elements are not easily displaced.
6) Strong wettability and welding performance.
7) The storage time in the refrigerated environment is up to 12 months, the stickiness is long-lasting, and it is not easy to dry out.

2. Lead-free solder wire

The raw material of lead-free solder wire 0.8mm is made of tin ore points (fewer trace impurities). The rosin core of the product is prepared by mixing high-quality rosin and developed organic acid. The product has fast welding speed, less smoke, less spatter, high solder spotlight, and a wide range of uses. It can be widely used in welding LED, household appliances, computers, and microelectronics.

Product features:
1) Good activity, low melting point; fast welding speed, effectively reducing the impact on components during the welding process, high insulation resistance, and good electrical performance.
2) The solder joints are bright and firm; good wettability and expansion ability make the solder joints smooth, and the ability to remove the oxide film efficiently protects the brightness of the solder joints.
3) Environmentally friendly, fresh smell and less smoke; environmentally friendly high purity, low melting point, and minor splash.
4) No cleaning, easy to use; few other impurities, sufficient tin ore degree, few ion residues, no cleaning assembly process for electronic products, clean and beautiful.
5) High-purity tin wire with sufficient degree (99.3% tin content); brand-new tin ore, refuse to use recycled waste tin, and the surface is silvery-white and bright.
6) High-purity tin ore; it is made of new high-purity tin ore, with sufficient degree and smooth surface of the tin wire.

3. BGA lead-free solder balls

Solder balls mainly connect semiconductor chips, circuit boards, and PCB boards to transmit electronic signals and small ball-shaped tin electronic parts. The diameter of solder balls for IC packaging is available in 0.2-0.76MM. The larger the size, the larger the particles and the larger the number.

Uses: BGA lead-free solder balls are widely used and can be used in motherboard maintenance, various PCB production welding, chip production welding, etc.
Product features: Add trace elements to improve the anti-oxidation ability of solder balls.
Solder leaves residue and fumes when used. Therefore, when using solder, it is recommended to use it with a solder smoking apparatus, effectively preventing the absorption of toxic solder and lead fumes. Avoid accidentally inhaling poison gas that can cause headaches, dizziness, eye problems, and other health-damaging ailments.

By introducing the above content, do you have a clear understanding of flux and solder paste?