After Solder Paste soldering, we may find uneven edges, burrs or stains on the surface. What should we do? Below, the Solder Paste Manufacturer explains:

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

1. The PCB after soldering looks blurry: the edges of the joint are uneven and there are burrs on the surface.

Reason 1: the viscosity of the solder paste is relatively low.

Solution: replace the solder paste and choose one with an appropriate viscosity.

Reason 2: the walls of the stencil apertures are rough.

Solution: before the stencil is accepted, use a 100-power magnifier to inspect the polish of the stencil aperture walls.

Reason 3: the coating on the pad is too thick and the hot-air leveling is poor, causing unevenness.

Solution: ask the PCB manufacturer to improve this and adopt gold plating, OSP or another pad coating process.

II. PCB surface contamination

Reason 1: the underside of the stencil is coated with solder paste.

Solution: increase the frequency of cleaning the underside of the stencil.

Reason 2: incorrectly printed PCBs were not cleaned thoroughly enough.

Solution: be sure to clean the reprinted PCB thoroughly.

Note: after the PCB is cleaned, blow it through with an air gun, because many tiny tin balls invisible to the naked eye can remain lodged in the PCB gaps.

Now do you know how to solve burrs and stains after solder paste soldering? If you have any other questions, welcome to follow JJY Solder Paste Factory and leave us a message online!