What causes bubbles in lead-free solder paste solder joints and how can they be solved?

Recently, quite a few customers have been asking why they are using itSolder pasteWhen welding, there may be some bubbles at the weld points from time to time. Does this have any impact on the product? The appearance of bubbles in the solder joints is quite serious. If bubbles occur inside the solder joints, it not only poses a significant threat to the stability of the solder joints but also increases the probability of component failure. Today, Shenzhen JJY Solder Paste Factory is here to share with you how to solve the problem of bubbles produced by lead-free solder paste during soldering?

The formation of bubbles in solder joints is usually due to the flux in lead-free solder paste. Compared with ordinary solder paste, lead-free solder paste uses moreSACThe alloy is also larger than the tin-lead alloy of ordinary solder paste, and the melting point of lead-free solder paste is higher. The flux also needs to function at a higher temperature, which greatly increases the possibility that volatile substances will fall into the molten solder before volatilization.

Another reason is that ordinary air reflow soldering equipment cannot create a vacuum environment inside, and thus cannot effectively remove the oxygen inside the furnace and the bubbles inside the solder joints. To prevent the oxidation of solder joints, nitrogen is filled in the reflow soldering furnace. When the pressure of nitrogen is higher than the atmospheric pressure, it will instead cause more bubbles to form inside the solder joint.

How to solve the problem of bubbles produced by lead-free solder paste during soldering?

Because Lead-free solder pasteDue to the characteristics of the constituent metals and fluxes, it is difficult for us to directly avoid the formation of bubbles. So, how can we reduce the occurrence of bubbles? Although it is difficult to avoid the formation of bubbles, we can remove the bubbles inside the solder joints through some methods.

Firstly, we can perform gradient vacuuming right after the welding is completed and before it cools down. That is, the vacuum degree gradually increases. Since the solder has not yet solidified after welding, at this time, bubbles are scattered at various positions of the weld point. Gradient vacuuming can first remove the bubbles from the surface, while the bubbles at the bottom will gradually move upward. As the pressure decreases, the bubbles will evenly float out. If we instantly evacuate the air, the internal bubbles will quickly overflow, leaving explosive openings on the solder joints and also affecting the stability of the solder joints. In addition, pre-vacuuming should be carried out. Before heating lead-free solder paste, the oxygen in the working area should be evacuated to prevent the formation of an oxide film on the solder during the heating process. The vacuum environment can also increase the wetting area.

Shenzhen JJY Industrial Technology Co., Ltd. mainly engages in:QFNHigh solder climbing rate solder paste, zero halogen solder pasteVOIDLow-porosity solder paste, laser solder paste, water-washed solder paste, and high-reliability ones used in military, aerospace, power, photovoltaic and other industriesSn62Pb36Ag2Solder pasteSn62.8Pb36.8Ag0.4Solder paste6337Solder paste, transparent and colorlessLEDHigh-brightness anti-monument solder pastemini-LED/micro-LEDDie bonding solder paste, high-reliability lead-free low-temperature solder paste, low-temperature solder paste for heat sinks, professional solder paste for hardware soldering, lead-free medium-temperature solder paste, lead-free high-temperature solder paste0307/105/305Manufacturers of solder paste and other soldering materials.