1. It is
tin paste: choose No. 5 or No. 6 powder with very small particles.
2. Packaging: Most of the packaging is 30ml or 10ml syringe packaging.
3. Function: It is mainly used to replace the silver glue welding core.
4. It is a flux paste, which can be welded with semi-non-metallic materials. Understand the coating of the core piece to understand.
5. The solid crystal solder paste is a bonding material with a thermal conductivity of about 40W/M·K, such as SnAgCu and other metal alloys as the substrate, which fully meets the environmental protection standards such as RoHS and halogen-free, and is used for LED chip packaging and other power devices such as diodes. The package can realize the fusion between metals, which can greatly reduce the thermal resistance of the LED heat dissipation channel, while achieving better conductivity and connection strength.
Solder Paste Bubble Complete Solution
1. Choose a relatively high-quality solder paste.
2. Pay attention to the printing speed and angle adjustment of the printing machine.
3. Reflow soldering preheating zone 160-190 should be about 90 seconds as much as possible.
If the above still doesn't work, there is another way to make a sample.
1. Pre-tin the PCB pad with solder wire and soldering iron, and then level it.
2. Normal operation.
3. Check if the bubbles disappear.
If more than 90% of the bubbles have been tried, they will decrease or even disappear, and the bubble area requirement of less than 20% of DELL can be achieved.
Why does the solder paste become thinner and thinner?
There are three kinds of changes in viscosity of lead-free solder paste during normal printing:
One: Reduced viscosity----If the solvent in the solder paste manufacturer's flux formula is less volatile, it will become thinner and thinner.
Two: Viscosity increases - On the contrary, if the solvent in the formula is very volatile, it will appear more and more dry.
Three: The viscosity first decreases and then increases (the slope is very small) and finally remains stable - this phenomenon should be an ideal situation, that is, the proportion of each component of the flux is just right.
At present, there should be no problem with the quality of solder paste of mainstream brands on the market. Generally, the third phenomenon occurs. Therefore, once the above one or two situations occur, you should first confirm the ambient temperature and humidity on the site, the internal temperature of the equipment and the ventilation status. Whether it is abnormal or not, if such defects still occur under normal process parameters, the technical parameters of the solder paste itself should be confirmed.