Introduction
In the SMT line production, reflow oven machine, as the core equipment, is a widely used soldering process. About Soldering, its materials mainly include solder paste and solder wire. So, how to make a scientific choice between the two? What are their respective characteristics and applicable scenarios? This article will provide you with a detailed analysis to help you understand the difference between solder paste and solder, advantages and application recommendations.
I. What is solder paste?
Solder paste is a homogeneous mixture of alloy solder powder, paste flux and some additives mixed with a certain viscosity and good thixotropy of the paste. It is a homogeneous, stable mixture. At room temperature solder paste can be electronic components in the first stick in the established position, when the solder paste is heated to a certain temperature, with the solvent and part of the additives volatilisation, alloy powder melting, the solder paste and then flow so that the soldered components and pads interconnected together by the cooling of the formation of permanently connected to the solder joints. It is mainly used in SMT, the electronic components will be precisely soldered to the PCB.
Features of solder paste
- Wide range of applications: particularly suitable for high-density, multi-leg electronic components.
- Pre-printing: The solder paste is accurately spread on the pads by means of a SMT solder paste screen printer machine.
- Easy automation: Efficient production in conjunction with automatic chip mounter.
- Easy to adjust the shape of solder joints: Adjust the amount and thickness of solder paste according to process requirements.
II. What is solder Wire / solder bar?
Solder Wire / Solder Bar usually refers to the metal wire material used in traditional manual soldering and some automated soldering equipment. It consists of pure tin or alloys such as tin-lead, tin-silver-copper, etc. It has a low melting point and melts easily.
Characteristics of solder
- Preferred for conventional soldering: suitable for processes such as piercing and wave soldering machine.
- The melting point of the solder is lower than that of the workpiece to be soldered.
- It is easy to join with the soldered workpiece, to have a certain resistance to pressure.
- To have good electrical conductivity.
- To have fast crystallisation speed.
III. The main comparison between solder paste and solder wire
| Aspect | Solder Paste | Solder wire |
| Main Applications | SMT | Manual Soldering, Wave Soldering, Automatic Spot Soldering |
| Appearance | Adhesive, Paste | metal wires or strips solid (rods, wires) |
| Soldering process | Pre-printing, reflow soldering | Soldering heat (manual or automatic) |
| Suitable scenario | High-density circuit boards, small components | Large components, piercing, wire bonding |
| Difficulty of operation | Easier to automate, requires specialised equipment | Flexible, suitable for manual or automatic feeding |
| Soldering quality control | Easy to control solder joint shape and position | Manual skills required to control solder joint quality |
IV. Selection Guide: Solder Paste VS Solder Wire, How to Choose?
1. When to use solder paste?
- Performing high-density SMT assembly
- Pursuing fine solder joint control
- Realising automated SMT line production
- Need fast and clean soldering results
2. When to choose solder wire?
- For manual soldering or low-density assembly
- Need to solder large parts such as copper wires, transformers, etc.
- Using wave soldering or perforation soldering process
- Field maintenance or repair
3. Key Considerations
- Type and density of products to be welded
- Scale of production and level of automation
- Budget and equipment matching
- Process proficiency and technical requirements
V. Suggestions for optimisation of soldering materials
- Regular testing: Control the viscosity of solder paste and flux composition to ensure the quality of solder joints.
- Reasonable storage: solder paste and solder should be kept away from light and low temperature to prevent oxidation.
- Process parameter adjustment: Ensure that the reflow temperature profile is adapted to the solder paste characteristics.
- Choose a reliable supplier: ensure that the material meets industry standards and environmental requirements.
VI. The future trend: the innovative development of soldering materials
With the miniaturisation and complexity of electronic products, soldering materials are also constantly innovating – from environmentally friendly lead-free to high-performance alloys, from intelligent detection to automatic feeding, the industry is moving towards a more efficient and greener direction.
Conclusion
Solder paste and solder wire are the same as welding materials, but their respective characteristics and application scenarios vary greatly. This article helps you to put the solder paste and solder together to compare and analyse, understand the differences and advantages between the two, in the future procurement, process design and quality control to make a more informed choice. pcba factory to choose the right soldering material is to ensure the reliability of the electronic product and production efficiency of a key step.
Company profile
Zhejiang NeoDen Technology Co., LTD., founded in 2010, is a professional manufacturer specialized in SMT pick and place machine, reflow oven, stencil printing machine, SMT production line and other SMT Products. We have our own R & D team and own factory, taking advantage of our own rich experienced R&D, well trained production, won great reputation from the world wide customers.
We believe that great people and partners make NeoDen a great company and that our commitment to Innovation, Diversity and Sustainability ensures that SMT automation is accessible to every hobbyist on everywhere.
Post time: May-15-2025