1. Porosity is typically an issue associated with welded joints.
2. This is particularly true when using PCB technology to reflow solder paste.
3. In the case of leadless ceramic chips, most large pores (>0.0005 inches/0.01 mm) are found between the LCCC solder joints and the printed circuit board solder joints.
4. Additionally, only a few small pores exist in the fillet weld near the LCCC castle.
5. The presence of these pores can significantly impact the mechanical properties of the welded joint.
6. This results in reduced strength, ductility, and fatigue life of the joint.
7. As pores grow, they may coalesce into extensible cracks, leading to fatigue.
8. Moreover, pores can increase stress and variance in the solder, contributing to failure.
9. The Shanghai SMT chip processing plant has noted that solder shrinkage during solidification, along with gas delamination and entrained flux during soldering, are also contributing factors to porosity.
10. In the PCB soldering process, the mechanisms that lead to pore formation are quite complex.
11. Generally, pores arise from the exhaust of flux trapped within the solder in a sandwich structure during reflow (2,13).
12. The formation of these pores is primarily influenced by the solderability of the metallized area.
13. It varies with decreased flux activity, increased metal load of the powder, and larger coverage area beneath the lead joint.
2. This is particularly true when using PCB technology to reflow solder paste.
3. In the case of leadless ceramic chips, most large pores (>0.0005 inches/0.01 mm) are found between the LCCC solder joints and the printed circuit board solder joints.
4. Additionally, only a few small pores exist in the fillet weld near the LCCC castle.
5. The presence of these pores can significantly impact the mechanical properties of the welded joint.
6. This results in reduced strength, ductility, and fatigue life of the joint.
7. As pores grow, they may coalesce into extensible cracks, leading to fatigue.
8. Moreover, pores can increase stress and variance in the solder, contributing to failure.
9. The Shanghai SMT chip processing plant has noted that solder shrinkage during solidification, along with gas delamination and entrained flux during soldering, are also contributing factors to porosity.
10. In the PCB soldering process, the mechanisms that lead to pore formation are quite complex.
11. Generally, pores arise from the exhaust of flux trapped within the solder in a sandwich structure during reflow (2,13).
12. The formation of these pores is primarily influenced by the solderability of the metallized area.
13. It varies with decreased flux activity, increased metal load of the powder, and larger coverage area beneath the lead joint.
