As the core component of electronic products, the quality stability of a PCBA board directly relates to the device's functionality and lifespan. However, during actual production or use, PCBA boards may sometimes exhibit cracking or bubble formation. These issues not only affect circuit performance but can also pose safety hazards. A thorough analysis of their causes helps to mitigate risks at the source and enhance product reliability.

Common causes of PCBA board cracking are often related to material selection and process control. The substrate material is a key factor influencing crack resistance. If a material with a low Tg (glass transition temperature) is selected, the substrate may soften and lose structural strength in high-temperature environments, leading to cracking at stress concentration points. For example, during reflow or wave soldering processes, improper temperature profile settings can cause localized overheating. This may result in excessive differences in the coefficients of thermal expansion between the substrate and components, generating internal stress that can eventually lead to cracking after prolonged use. Additionally, mechanical stress is a significant contributing factor. If a PCBA board is subjected to severe vibration, impact, or bending during assembly, transportation, or use, exceeding the material's tolerance limits, the substrate or solder joints may crack. For instance, insufficient design provisions for mechanical buffering or overly dense component layouts can reduce overall impact resistance.

The occurrence of bubble issues is often associated with soldering processes and environmental control. During reflow soldering, if the flux does not volatilize completely or the soldering temperature is insufficient, gases within the solder cannot escape in time, forming bubbles inside the solder joints. These bubbles reduce the mechanical strength and electrical conductivity of the solder joints and, in severe cases, can lead to cold joints or open circuits. Furthermore, environmental humidity is a potential source of bubbles. If a PCBA board is exposed to a humid environment for too long, moisture can adsorb onto the substrate or component surfaces. During high-temperature soldering, this moisture rapidly vaporizes into steam. If the steam cannot escape promptly, it forms bubbles within the solder joints or the substrate itself. For example, PCBA boards that have not undergone strict pre-baking for moisture removal are more prone to such issues during soldering.

Addressing cracking and bubble problems requires comprehensive prevention and control from three aspects: design, process, and environment. During the design phase, priority should be given to selecting substrate materials with high Tg, and components should be laid out reasonably based on the application scenario to avoid stress concentration. Simultaneously, sufficient mechanical buffering space should be **allocated** to improve impact resistance. Regarding process control, soldering temperature profiles must be strictly set to ensure complete flux volatilization and uniform solder flow. For humid environments, PCBA boards must be thoroughly baked to remove moisture before soldering, minimizing water interference. Environmental management is equally critical. Production workshops should maintain constant temperature and humidity, reducing the effects of dust and static electricity. During transportation and storage, shock-proof packaging should be used to avoid mechanical damage.

Although the causes of cracking and bubbles in PCBA boards are complex, risks can be effectively reduced, and product stability and reliability enhanced through scientific material selection, refined processes, and strict environmental control.