After the solder paste soldering is completed, the edges are uneven, there are burrs or stains on the surface?

If you find uneven edges, burrs or stains on the surface after Solder Paste soldering, don't worry. Here are the solutions. Now, let the Solder Paste Manufacturer explain them to you:

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.

Generally, to solve a problem you must first analyze where the root cause lies and why the burrs appear. It is possible that Solder paste viscosity is too low, or it may be caused by overly rough stencil walls. In that case, first check whether the stencil walls are polished well, and then re-run the soldering. If you have any questions, please feel free to consult us.

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After the solder paste soldering is completed, the edges are uneven, there are burrs or stains on the surface?

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