Step 1: Identify Inspection Stages

Objective: Define where inspections are needed in the manufacturing process.
Common stages include:

• After solder paste printing

• After component placement (SMD/THT)

• After reflow or wave soldering

• After manual soldering

• Before functional testing

Action: Create a process map or inspection plan that specifies checkpoints.

Step 2: Define Inspection Criteria

Objective: Standardize what to check and what constitutes a defect.
Includes:

• Component placement accuracy

• Polarity/orientation

• Solder joint quality

• Missing components

• Tombstoning, bridging, cold joints

• Flux residue or contamination

Action: Refer to IPC-A-610 standards and customer-specific quality plans.

Step 3: Sampling Plan

Objective: Decide how many units to inspect from a batch.

Examples of Sampling Methods:

• 100% Inspection: Critical stages or high-value products

• AQL Sampling (Acceptable Quality Level): Follows MIL-STD-105 or ISO 2859

• Random Spot Checks: For mature, low-defect-rate processes

Action: Document sampling frequency and lot sizes in the quality plan.

Step 4: Perform Inspection

Objective: Execute the inspection using trained operators or automated tools.

Techniques Used:

• Visual Inspection – Manual observation using magnifiers

• AOI (Automated Optical Inspection) – Detects solder defects, wrong/missing parts

• X-Ray Inspection – For hidden joints like BGA

• Microscope Inspection – For fine-pitch components

Action: Use checklists or inspection software to record results.

Step 5: Record Findings and Non-Conformities

Objective: Maintain traceability and enable process improvement.

Key Data to Record:

• Serial or lot number

• Inspection results

• Defect type and location

• Inspector name and timestamp

Action: Use ERP or MES system to log data or maintain manual logs.

Step 6: Segregate Defective Units

Objective: Prevent defective items from continuing down the line.

Procedure:

• Place defective boards in a red bin or reject rack.

• Label clearly with rejection tag (NCR – Non-Conformance Report).

• Forward to rework station or quality team.

Action: Follow FIFO and ESD-safe handling procedures.

Step 7: Trigger Corrective and Preventive Actions (CAPA)

Objective: Eliminate root causes of defects and prevent recurrence.

Activities:

• Root cause analysis (using 5 Whys, Fishbone diagram)

• Process or equipment adjustment

• Operator re-training

• Update work instructions or inspection criteria

Action: Document CAPA actions and verify effectiveness.

Step 8: Feedback to Production and Quality Teams

Objective: Share insights for continuous improvement.

Methods:

• Daily quality review meetings

• Monthly defect trend analysis

• Quality dashboards or reports

Action: Use metrics like DPMO (Defects Per Million Opportunities) to track quality performance.

✅ Compliance and Standards Followed

• IPC-A-610 – Acceptability of Electronic Assemblies

• ISO 9001 – Quality Management System

• ESD Control Standards (ANSI/ESD S20.20)

• Customer-specific quality requirements