Causes Of Cold Solder Caused By Pcba Pros

Hello everyone, Have you ever encountered PCBA cold solder joints? How did you solve this problem? Did you get online help?

today I want to introduce to you a common bad phenomenon in PCB mounting, that is cold solder.cold solder caused by PCBA  PROS

First of all, we need to understand what cold solder is. A soldering process is used in PCBA processing.

Cold soldering is also known as incorrect soldering. It is a state of inaccessibility at all times. It’s kind of bad soldering. It is a very important reason for the high repair rate prior to PCBA.

PCB welding problem

Whether it’s industrial PCB assembly or prototyping with new trends , most engineers face the problem of unreliable electronic products due to cold solder joints.

As a professional PCB manufacturer, 86PCB used to be concerned about cold solder joint. Because of these questions, we took the risk of doing more research on this particular topic and trying to answer the questions that might confuse PCB designers.

The reasons for PCBA solder joints are as follows:

1.Oxidation of pads and component pins

Oxidation of pads and component pins

It can easily result in the liquefied state solder paste. not fully infiltrating the pads during reflow soldering .the solder creeping up, resulting in virtual soldering.

For this situation we also have a method of treatment: in general, it can be scraped off with a small blade. it does not affect the metal components. and it can also be cleaned with alcohol.


2.PCBA Cold solder-Too little tin

In the solder paste printing process. there is little tin due to the small opening of the stencil or the insufficient pressure of the squeegee. so that the amount of solder paste in the solder paste is insufficient . the components cannot be completely soldered. resulting in improper soldering.

In this case, the commonly used remedy is: after the assembly work is completed. manual tinning is performed in the later stage.


3.The temperature is too high or too low


Except for low temperature (which can cause false welding), the temperature should not be too high. Because the temperature is too high. Not only will the tin flow, but also the surface oxidation rate will increase, which may also lead to erroneous soldering or soldering failure.


4.Low melting point of solder paste


Some low temperature solder pastes have relatively low melting points.  The component pins and board materials of solid components are different. Their thermal expansion coefficients are also different.
After a long time, under the action of thermal expansion and contraction. The working temperature of the part changes, resulting in false welding.

solder paste

5.The quality of the Cold solder paste.


The quality of solder paste is not good. The solder paste is easily oxidized. The loss of flux will affect the soldering performance of the solder paste and lead to incorrect soldering.

Generally, the situation of PCBA virtual soldering is very complicated . arequires strict production process control to optimize the process flow.

Finally, I hope this article can be helpful to you.


All of the Above!-PCBA Cold solder

Don’t panic. Take your time.  Most joints can be repaired with patience.  If the solder refuses to flow the way you want it to:

  1. Stop and let the joint cool.
  2. Clean and tin your iron.
  3. Clean off any burnt flux from the joint.
  4. Let the iron come back up to temperature.
  5. Then reheat the joint and try again.
  6.  Using A Multimeter to Check Cold Solder Joints
  7. Testing by use of resistance (ohms)
  8. Testing by use of continuity
  9. Visual inspection of cold solder joints

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