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How to solve the solder scooped on welding

In an electronic manufacturing plant, they are responsible for the production of high-density electronic components, including 0.4/0.5 pitch component materials, each material has 60 or more pins. During the soldering process, they found that some of the solder scooped on welding are appeared. After investigation and analysis, they found the following possible scenarios that caused the issue.

In this article, we will illustrate 3 parts, that are the definition of solder scooped, the reasons that causes solder scooped and how to solve this trouble. Come and take a look with me.

Table of Contents

What is the solder scooped phenomenon during welding?

What is solder scooped phenomenon
What is solder scooped phenomenon

The solder scooped phenomenon during welding means that depressions or cavities appear on the surface of the solder joint or solder pad. And these depressions or cavities are formed due to defects or uneven distribution of solder. Specifically, the solder scooped on the welding refers to the phenomenon that the solder materials (usually tin) do not fully wet the surface of the welding, forming voids or depressions.

The phenomenon of solder scooped on the welding might bring the following effects.

1. Reduced electrical connection reliability
Solder scooped can lead to poor localized electrical connections on the soldered surface, reducing solder joint reliability. Poor solder joints may cause problems such as unstable electrical signal transmission, current overload, or signal loss, affecting the normal operation of the device.

2. Weakened mechanical capability
The solder scooped on welding may lead to a decrease in the mechanical capability of the soldering point. When the solder joint is subjected to external force or vibration because the solder materials in the solder scooped phenomenon are insufficient. It may easily break or loosen, resulting in a decrease in the mechanical reliability of the soldered part.

3. Poor heat dissipation performance
The solder scooped will lead to the irregular geometry of the soldering surface, which will affect the heat dissipation performance of solder joints. Poor heat dissipation of solder joints may lead to temperature rise, which in turn affects the performance and life of the plug-in material, and even causes equipment failure or damage.

4. Decreased quality stability
Solder scooped on the welding may lead to unstable soldering quality. During the production process, the solder scooped on the welding may not be easy to be found, resulting in differences in soldering quality among production batches. Unstable welding quality may increase the failure rate of products, affecting production efficiency and product reliability.

Also read: The complete guide to PCB pad :types, size, spacing, repair and comparison

How to solve the solder scooped on welding

What reasons result in solder scooped on welding?

The following are some factors that can cause the solder scooped phenomenon.

01 The design of the welding is unreasonable.
The surface of the welding design for 0.4/0.5 pitch plug-in materials (single material with more than 60 pins) is unreasonable. This may include improper solder pad design, small solder pad size and solder pad spacing. Improper solder pad design can result in insufficient wetting of the solder to the surface of the solder pad, resulting in the solder scooped phenomenon.

02 Inappropriate welding process parameters
The selection and adjustment of parameters such as welding temperature, welding time, and welding pressure are very important. If the temperature is too high or the time is too long, the solder may be excessively melted and volatilized, causing the solder scooped. In addition, improper soldering pressure may also cause the solder to not fill the solder pad gap sufficiently, thereby forming a solder scooped.

03 Inappropriate or insufficient welding flux :
Welding flux has the effect of improving the wettability of the soldering surface and removing oxides. If the selected solder flux is not suitable for the characteristics of the insert material or if the amount used is insufficient, the solder may not sufficiently wet the pad surface, resulting in the formation of solder voids.

Also read: Understanding PCB flux : a comprehensive guide 

How to solve the solder scooped phenomenon?

There are some measures that can fix the solder scooped phenomenon?

1. Optimize welding parameters
Check and adjust welding parameters, including temperature, time and pressure, etc. Depending on the specific situation, it may be necessary to reduce the soldering temperature, shorten the soldering time, or increase the soldering pressure to improve the wettability and filling of the solder and avoid the occurrence of solder scooped.

2. Improve the design of the welding surface
Re-evaluate the design of the soldering pad for the soldering surface with solder scooped. Consider adjusting solder pad size, spacing, and shape to ensure that the solder pads provide sufficient surface area and wetting performance to avoid solder scooped.

3. Clean and pre-treat the surface of the material
Ensure that the surface of the plug-in material is clean and pollution-free, and remove pollutants such as moisture, oil and oxides. Use appropriate cleaning agents and process steps, such as ultrasonic cleaning and hot air dehumidification, to improve solder wetting performance and reduce the risk of solder scooped.

4. Select the appropriate welding flux
According to the characteristics of the plug-in material and welding requirements, select the appropriate type and amount of welding flux. Solder flux can improve solder wetting capability and remove oxides, reducing the occurrence of solder scooped phenomenon.

5. Regular maintenance and inspection of welding equipment
Make sure that the welding equipment is operating normally and that the welding tips are not damaged or worn. Regularly inspect and maintain equipment to ensure accurate temperature control and stable welding pressure to improve welding quality and avoid welding defects.

6. Repair the existing solder scooped issues
If the solder scooped phenomenon has already occurred, you can try to use repair welding or a heat gun to repair it. Pay attention to temperature and time control during the repair process to avoid further damage.


Founded in 2005, IBE Electronics has accumulated more than 18 years of PCB and PCB assembly manufacturing experience. During PCB and PCB assembly, we introduced advanced equipment. We are dedicated to OEM/ODM PCB and PCBA manufacturing starting from design, manufacture, assembly, testing and shipment.

  • Reduced electrical connection reliability
  • Weakened mechanical capability
  • Poor heat dissipation performance
  • Decreased quality stability
  1. The design of the welding is unreasonable.
  2. Inappropriate welding process parameters
  3. Inappropriate or insufficient welding flux :
  • Optimize welding parameters
  • Improve the design of the welding surface .
  • Clean and pre-treat the surface of the material
  • Select the appropriate welding flux

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