With the development of society and the changes of the times, lead-free no-clean solder paste has been applied to all walks of life, and the requirements for environmental protection are getting higher and higher, so what are the advantages of lead-free no-clean solder paste compared to traditional lead-free solder paste? What about the advantage?

First of all, lead-free no-clean solder paste printing has good rolling and tin drop properties, and can also complete fine printing on pads with a pitch as low as 0.3mm. During continuous printing, its viscosity changes very little, and the stencil has a long operating life. , it will not dry for more than 12 hours, and still maintain a good printing effect; it still maintains the original shape for several hours after printing, basically no slump, and the patch components will not be offset; good resistance to cold and heat slump. Of course, if you want to know if a solder paste is suitable for your product, the easiest way is to try it out. So what aspects can be used to evaluate a solder paste in the use of solder paste?

First, after soldering, look at the appearance without malfunctioning. Most of the malfunctions are due to process technical problems or operation problems. Generally speaking, because the solder paste has less defects, the appearance mainly depends on whether there are any defects after soldering. Residual? Are there tin beads on the surface? Will it corrode the deck?

Second, go to the evaluation after printing, if the solder paste printing occurs: bridging, skin layer, insufficient adhesion, collapse, blur, five kinds of defects, except for their own operation problems, as far as the solder paste itself is concerned, it can be identified:

1. Bridge, collapse, blur, the proportion of metal components in the solder paste is uneven; the viscosity is insufficient, and the tin powder particles are too large.

2. When the cortex occurs, the activity of the flux paste in the solder paste is too strong. If it is a lead solder paste, the lead content may be too high.

3. Insufficient viscosity. It may be that the solvent in the solder paste is easy to volatilize, the proportion of metal in the solder paste is too high, and the particle size may not match.

And because the viscosity is lower than that of ordinary SMT solder paste, lead-free solder paste is relatively easier to collapse, and lead-free no-clean solder paste has a larger surface tension than traditional solder paste when it is melted, so if it collapses before melting The disks are connected, and there is a greater probability of bridging after reflow. Therefore, good resistance to cold and thermal collapse is particularly important. Choosing the right solder paste is an important way to avoid bridging, reduce the amount of repairs, and improve production efficiency and product reliability.

Secondly, the viscosity changes little and the service life is long. Viscosity changes will cause changes in print volume, especially in printing, so maintaining a relatively stable viscosity is very important to ensure the consistency of solder joints. In most cases, the viscosity of lead-free no-clean solder paste will increase while the viscosity will decrease. For example, lead-free solder paste will almost lose its viscosity after drying, which will cause the solder paste to be topped off due to loss of viscosity when plugging in. cause solder leaks. Lead-free no-clean solder paste has good soldering performance and can show appropriate wettability in different parts; it can adapt to the requirements of different grades of soldering equipment, and does not need to be soldered in a nitrogen-filled environment, within a wide reflow oven temperature range Still can show good welding performance. There are very few residues after soldering, the color is very light, and it has a large insulation resistance, which will not corrode the PCB, and can meet the requirements of no-cleaning.