SMT Technology Advanced - Reflow: How to accurately locate and solve BGA air welding problems, improve productivity and quality

　　I. Core Issues Analysis

　　Challenges in Pad Design:

　　Size Limitation: Excessively small pads limit solder paste volume, affecting solder joint formation.

　　Shape Compatibility: Pads must align with BGA pin shapes to maximize contact area.

　　Layout Rationality: Excessive spacing can cause interference, while edge distances must prevent stress impacts.

　　Difficulties in Solder Paste Printing:

　　Uniformity Challenge: Printing parameters, worn squeegees, and solder paste quality impact uniformity.

　　Precision in Volume Control: Too little paste results in incomplete solder joints, while too much can cause bridging or short circuits.

　　Poor Release Effect: Residues and uneven distribution require cleaning and release optimization.

　　Temperature Profile Control:

　　Criticality of Preheating: Insufficient preheating leads to poor melting and high risk of open solder joints.

　　Welding Temperature Range: Moderation is key, avoiding oxidation or damage.

　　Cooling Strategy: Balanced speed to prevent stress and crystallization issues.

　　Protection Against BGA Ball Oxidation:

　　Cleaning & Anti-Oxidation: Clean pins are essential, with proper storage to prevent oxidation.

　　Precision in Component Placement:

　　Accuracy & Stability: Deviations and insufficient pressure both lead to poor contact.

　　Material Quality Control:

　　Solder Paste & Flux: High-quality materials with good wettability and stability.

　　Comprehensive Factor Consideration:

　　Board Deformation & Environmental Interference: These cannot be overlooked.

　　II. Targeted Improvement Strategies

　　Innovation in Pad Design:

　　Customized designs, matching pins, optimized layouts, minimizing residues.

　　Precision in Solder Paste Printing:

　　Parameter adjustments, equipment maintenance, release agents to ensure uniformity.

　　Fine-tuning the Temperature Profile:

　　Sufficient preheating, precise welding temperatures, suitable cooling speeds.

　　Enhanced Pre-processing of Pins:

　　Cleaning to remove oxidation, proper storage to maintain optimal pin condition.

　　Precise Control of Component Placement:

　　High-precision equipment, adequate pressure to ensure good contact.

　　Enhancing Board Quality:

　　Rigorous checks for flatness, controlled storage environments to reduce deformation risks.

　　Comprehensive Quality Monitoring:

　　Visual inspections, X-ray, and other methods to promptly detect and resolve issues.