JJY solder Paste Manufacturer shares: Lead-free low-temperature soldering Solder paste The usage method, generally speaking The basic principle for the use and storage of lead-free solder paste is to minimize its contact with air to prevent oxidation. If lead-free solder paste is exposed to air for a long time, it will cause oxidation of the solder paste and corresponding changes in the proportion of flux components. The result will be: the solder paste will have hard skin, hard lumps, be difficult to melt, etc., and a large number of solder balls will be produced during the production process.

1:Heating stage:

In the heating zone, a portion of the volatile organic solvents in the solder paste volatilize, reducing the impact on the components.
Regulation: The slope of the temperature increase tangent is1.0～3.0℃/Seconds.
If the temperature increase rate is too fast, it may cause the fluidity and composition of the solder paste to deteriorate, leading to solder balls and bridging, etc. At the same time, it will cause the components to bear excessive internal stress and be damaged.

2:Heat insulation and preservation stage:
In this area, the solder paste gradually becomes active, and the chemical water treatment behavior gradually increases makePCBThe temperature is uniform everywhere before reaching the welding area.
Regulation: The temperature is110℃～138℃The time is90～150The slope of the temperature rise tangent should be lower than that of the second2/Seconds.

3:Reflow welding stage:
The alloy particles in the solder paste melt and form the surface layer of the solder joint under the effect of liquid interfacial tension.
Regulation: The maximum temperature is170～180℃,138℃The time above is50～80Seconds.
If the maximum temperature is too high or the re-soldering time is too long, it is very likely to cause Dark solder joints, carbonization and color fading of solder paste residues, and damage to components, etc.
If the temperature is too low or the re-soldering time is too short, it may cause the lubricity of the soldering material to decline and fail to produce high-quality solder joints. For components with high thermal conductivity, solder joints may even result in empty soldering.

4:Cooling stage:
After leaving the re-welding area, the base steel plate enters the cooling area. The key to demonstrating the cooling rate of the weld point is that the strength of the weld point will increase with the increase of the cooling rate.
Regulation:The slope of the desuperheating tangent is lower than4℃The cooling stop temperature should preferably not be too high75℃.
If the cooling temperature is too fast, it is very likely that the components will be damaged due to excessive internal stress, and there will be safety hazards such as cracks in the solder joints.
If the cooling temperature is very slow, it is possible to produce a large crystal structure, which may cause the compressive strength of the solder joint to decrease or the components to move.

The applicable scope of various methods is as follows:

1Manual drop coating method――It is used for extremely small batch production, the development stage of model prototypes and performance prototypes of new products, as well as the repair and replacement of components during the production process.

2Screen printing――It is used in medium and small batch production where the pad spacing of components is relatively large and the assembly density is not high.

3Metal template printing――It is used for mass production and assembly of products with high density, multiple leads and narrow pitch components.

The quality of metal template printing is relatively good and the service life of the template is long. Therefore, the metal template printing process should generally be given priority, which is what we often refer toSMTSteel mesh printing, surface mount technology. For more knowledge and usage methods about solder paste, please follow Double Chile Solder.

   Everyone believes that it's domesticLead-free solder paste The peak season for research and development and application has arrived, and surface mount solder paste will also rise, leading to the rapid development of the electronics industry.

    If you want to know about solder paste, lead-free solder paste, solder paste and other soldering issues, partners are welcome to consult Shenzhen JJY Industrial Technology Co., LTD. Let's learn and grow together! The solder wire, solder paste and solder rods of JJY brand are always waiting for partners to come and take them together.