What are the reasons for burrs and stains on the edges after lead-free solder paste soldering?

Generally in usSMTAfter the solder paste printing is completed, the surface mount is carried out. Although there are no problems in the solder paste surface mount, sometimes it is doneSMTAfter reflow soldering comes out of the oven, it will be found thatLead-free solder pasteThere will be some burrs, sharp points or dirt on the surface, and the edges are not very smooth. So what should be done when encountering such problems? Today, Shenzhen JJY Solder Paste Manufacturer will take you to learn about:

First, let's analyze the root cause of this phenomenon:

1.PCBAfter the board is soldered, the shape is blurry, the edge of the solder paste is uneven, and there are burrs on the surface

Reason1The viscosity of the solder paste is relatively low

Solution: Replace the solder paste and choose solder paste with appropriate viscosity

Reason2The walls of the steel mesh holes are rough

Solution: Before the acceptance of the steel mesh, use100Use a magnifying glass with a power supply to inspect the polishing degree of the steel mesh hole walls

Reason3:PADThe coating on it is too thick and the hot air leveling is poor, resulting in unevenness.

Solution: RequirementPCBThe manufacturer has improved and adopted gold plating.OSPWait for the pad coating process.

Ii.PCBSurface stain

Reason1The bottom of the steel mesh is coated with solder paste

Solution: Increase the frequency of cleaning the bottom of the steel mesh

Reason2Printed incorrectlyPCBThe cleaning is not clean enough.

Solution: ReprintedPCBBe sure to clean it thoroughly

Note:PCBAfter cleaning, it should be blown through with an air gun because there are many invisible tin balls stuck to the naked eyePCBIn the crevice.

The above is all the content that JJY has brought to you today about the reasons for burrs, sharp edges or dirt after using lead-free solder paste for soldering. If you want to know more about soldering related information, you can search for Shenzhen JJY for viewing. Welcome to follow.