Soldering solution to large heat absorption solder joints and easily oxidized pads

At present, the DIP soldering process mainly includes three types: manual soldering, automatic machine soldering and selective wave soldering. I believe that everyone has encountered the problem of easily oxidized pads and high heat absorption solder joints in the DIP soldering process. In this article, PCB SMT assembly factory SYS Tech will mainly introduce the solution to the large heat absorption solder joint and the easily oxidized pad, in the manual soldering and automatic machine soldering of the DIP soldering process.

I. Causes of large heat-absorbing solder joints and easily oxidized pads

• The pad is a large ground point.

• The copper foil of the PCB board is too thick and there are too many layers.

• The connector is connected with aluminum alloy heat sink or large metal parts.

• The double-sided PCB with OSP surface board has been reflowed for many times or exposed to the air for a long time, causing the copper pad to oxidize.
  
  

II. Methods to deal with large heat absorption solder joints and easily oxidized pads in manual soldering

• Solder after pre-coating flux on the pad.

• After preheating to a certain temperature on a dedicated preheating station, then perform soldering.

• In the previous process of SMD reflow processing, open a stencil to print the solder paste on the pad of assembly through hole, thereby increasing the solderability of the pad.

• Choose a soldering station with a higher power to increase the thermal compensation efficiency of the soldering iron to meet the soldering requirements. It is recommended to use a high-power lead-free soldering station above 120W.
  
  

III. automatic soldering machine solution to deal with large heat absorption solder joints and easy-to-oxidize pads

• Install special soldering jigs with preheating function to preheat the products in advance.

• Add a device for automatic adding flux to the tin feeding system, thereby increasing the solderability.

• Install a nitrogen generator on the automatic soldering to release nitrogen to protect the pads during soldering to avoid accelerated oxidation of the pads.

• In the previous process of SMD reflow processing, open a stencil to print the solder paste on the pad of assembly through hole, thereby increasing the solderability of the pad.
  

• Choose a soldering system with a higher power to increase the thermal compensation efficiency of the soldering iron to meet the soldering requirements. It is recommended to use a special intelligent soldering system for high-power automatic soldering machines above 150W.

oxidized pad in PCB

The above is the solution to large heat absorption solder joints and easily oxidized pads. SMT processing plants can choose to use one or several methods at the same time according to the specific situation.