Client specializes in the design, manufacture, and assembly of high-precision electronic parts for critical applications such as medical devices and aircraft. As a Tier 1 supplier to Original Equipment Manufacturers (OEMs) in highly regulated sectors, the company's core offerings include advanced sensor units, High-Density Interconnect (HDI) Printed Circuit Board (PCB) assemblies, and custom electronic sub-assemblies. Client prides itself on precision manufacturing, rigorous quality control, and robust R&D support, ensuring their components meet stringent performance and reliability standards.

Client faced a significant decline in quality and efficiency within the manufacturing sub-assembly process for their advanced sensor units. Over six months, the defect rate requiring rework escalated from a baseline of 0.8% to 2.5%. The primary issue stemmed from solder joint quality, specifically:

• Solder Voids: Air pockets within solder joints, compromising mechanical strength and electrical conductivity.

• Solder Bridges: Inadvertent connections between adjacent pads, causing short circuits.

• Weak/Incomplete Solder Joints: Connections lacking proper flow or metallurgical bond, leading to mechanical fragility and electrical instability.

These defects occurred during the assembly stage, impacting cost, quality, and delivery performance. The increased rework rate translated to an additional 2-day cycle time for affected units, directly hindering on-time delivery (a key performance indicator) and eroding profitability. The total estimated annual direct cost of these solder defects (rework and scrap) was a staggering ₹9,603,200.

Through a comprehensive data-driven approach encompassing Voice of Customer (VOC), SIPOC analysis, Value Stream Mapping (VSM), and in-depth statistical analysis of 12 months of production data, AEM Consultancy identified the root causes and developed targeted solutions:

Reduce Non-Value-Added Time:

The VSM revealed that over 98% of the total manufacturing lead time was non-value-added time, with parts sitting idle for extended periods, particularly between solder paste application on PCBs and the subsequent soldering process. This prolonged exposure to ambient temperature led to solder paste solidification or melting, directly causing voids and bridges.

• Action: Implement process re-engineering to minimize queue times and ensure a more continuous flow, specifically reducing the delay between solder paste application and reflow soldering. This could involve optimizing batch sizes, improving material handling, or introducing automation to reduce manual interventions that cause delays.

Standardize Operations and Retrain Staff:

Despite initial assumptions, statistical analysis showed that peak reflow temperature and squeegee pressure were not the primary drivers of defects. Instead, consistent defect rates across the year and a noticeable anomaly in Shift B indicated operator-specific variability and a lack of adherence to Standard Operating Procedures (SOPs). Each shift had developed its own "flow" rather than following standardized best practices.

• Action:

  • Update and Reinforce SOPs: Develop clearer, more detailed, and rigorously enforced SOPs for all critical steps of the solder sub-assembly process, particularly focusing on solder paste handling, component placement, and reflow oven operation.

  • Comprehensive Retraining: Conduct mandatory, hands-on retraining for all production staff, emphasizing adherence to the updated SOPs and the importance of process consistency.

  • Cross-Shift Training/Rotation: Implement a rotational system where staff from different shifts occasionally work together or swap shifts. This fosters knowledge sharing, breaks down "siloed" practices, and promotes consistent application of SOPs across all shifts. Special attention will be paid to understanding and addressing the specific challenges faced by Shift B.

Improve Inter-Shift Communication:

The fixed allocation of staff to specific shifts (A, B, and C) created communication barriers, even with "handover sheets." This limited direct interaction and understanding of operational nuances between shifts.

Action: Beyond the cross-shift training, establish formal daily or weekly inter-shift huddles or meetings to discuss production issues, share best practices, and facilitate direct communication regarding process challenges and solutions. Implement a digital logbook system that allows for more detailed, real-time updates and comments from all shifts.

The implementation of these solutions is projected to yield significant improvements for the client.

• Defect Rate Reduction: A sustained decrease in the defect rate, aiming to bring it well below the current 2.5% and ideally closer to or below the previous 0.8% baseline.

• Improved Quality: Enhanced consistency and reliability of solder joints, leading to a significantly higher First Pass Yield (FPY) from the soldering process.

• Cost Reduction: Substantial decrease in rework and scrap costs, directly contributing to improved profitability.

• Reduced Cycle Time: Elimination of the 2-day delay caused by rework, leading to faster production cycles and improved overall lead times.

• Enhanced Customer Satisfaction & Retention: Improved on-time delivery performance and consistent quality will strengthen client relationships, securing future contracts and bolstering client's reputation as a reliable Tier 1 supplier.

• Increased Throughput/Capacity: Optimized processes and reduced rework will free up technician time and manufacturing capacity, allowing for more efficient production of units.

These outcomes will be rigorously monitored through Critical-to-Quality (CTQ) metrics such as On-Time Delivery of Sub-Assemblies, Sub-Assembly First Pass Yield (FPY) from Soldering, Solder Joint Reliability, and conformance to IPC-A-610 Class 3 Standards.