Testing & Inspection
SPI, AOI, X-Ray, ICT, flying probe and functional testing to catch issues before shipment.
PCBA Technology & Capabilities
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PCBA Capabilities: Testing & Inspection
Our multi-layered testing and inspection strategy forms the foundation of quality assurance, designed to identify and eliminate defects at every stage of the assembly process. We implement a comprehensive suite of automated inspection and electrical test systems, creating a synergistic quality net that ensures only fully validated printed circuit board assemblies proceed to shipment.
1. Solder Paste Inspection (SPI)
Solder Paste Inspection is our primary process control checkpoint, occurring immediately after stencil printing to prevent soldering defects before component placement.
SPI Key Measurement Parameters & Control Limits
| Measurement Parameter | Purpose | Typical Control Limit (CPk ≥ 1.33) | Defects Prevented |
| Paste Volume | Measures total solder material deposited | ±30% of nominal volume | Insufficient solder, open circuits |
| Paste Height | Measures vertical dimension of solder deposit | ±25% of nominal height | Bridging, tombstoning |
| Paste Area Coverage | Measures percentage of pad covered by paste | >85% coverage | Poor wetting, skewed components |
| Paste Alignment | Measures X/Y offset from pad center | <25% of pad width | Component misalignment |
Technology: 3D laser scanning or Moiré interferometry
Process Integration: Real-time feedback to stencil printers for closed-loop process control
2. Automated Optical Inspection (AOI)
AOI systems perform high-speed, accurate visual inspection of assembled boards after reflow soldering to detect a wide range of visible defects.
AOI Defect Detection Capabilities
| Defect Category | Specific Defects Detected | Inspection Method |
| Component Defects | Missing components, incorrect parts, wrong polarity, misalignment | Shape recognition, color analysis |
| Solder Joint Defects | Bridging, insufficient solder, excess solder, lifted leads | Multi-angle lighting with grayscale analysis |
| Board & Printing Defects | Solder balls, foreign object debris (FOD), damaged pads | Contrast analysis, golden board comparison |
Technology: High-resolution cameras with programmable multi-angle lighting
Programming: CAD-based golden board comparison algorithms
3. X-Ray Inspection (AXI)
X-Ray inspection provides non-destructive examination of hidden solder joints and internal structures not visible to optical systems.
X-Ray Inspection Applications & Criteria
| Inspection Feature | Analysis Method | Acceptable Criteria (IPC Standards) |
| BGA/QFN Solder Joints | 2D or 3D CT imaging for ball shape and connection integrity | Full wetting, no bridging, proper alignment |
| Voiding Analysis | Measurement of gas pocket percentage within solder joints | <25% voiding per joint (application dependent) |
| Internal Barrel Fill | Inspection of through-hole solder fill in plated vias | >75% visual fill (IPC-A-610 Class 2/3) |
| Crack Detection | Identification of micro-fractures in solder joints | Zero cracks acceptable |
Technology: High-resolution micro-focus X-ray with 2D/3D imaging
Applications: BGAs, QFNs, connectors, internal PCB structures
4. In-Circuit Test (ICT)
ICT is a comprehensive electrical test that uses a bed-of-nails fixture to verify component presence, values, and basic functionality.
ICT Test Coverage & Fault Detection
| Test Type | Measurement Parameters | Faults Detected |
| Continuity Test | Resistance between test points and nets | Solder bridges, open traces, lifted pins |
| Passive Component Test | Resistance, capacitance, inductance values | Wrong value components, damaged parts |
| Semiconductor Test | Diode polarity, transistor basic function | Reverse-oriented diodes, faulty transistors |
| Analog & Digital Functional | Basic IC functionality, signal presence | Dead ICs, incorrect logic family |
Methodology: Custom vacuum or pneumatic bed-of-nails fixture
Best For: High-volume production with comprehensive fault coverage
5. Flying Probe Test
Flying probe testers use programmable moving probes for flexible electrical verification without custom fixtures.
Flying Probe vs ICT Comparison
| Attribute | Flying Probe Test | In-Circuit Test (ICT) |
| Fixture Cost | Zero - no custom hardware required | High - custom bed-of-nails fixture |
| Setup Time | Short - software programming only | Long - fixture design and manufacturing |
| Test Speed | Slower - mechanical probe movement | Faster - simultaneous test point contact |
| Flexibility | High - easy design change adaptation | Low - new fixture required for changes |
Ideal Applications: New product introduction (NPI), low-to-medium volume, prototypes, design validation
6. Functional Test (FCT)
Functional testing simulates the final operating environment to validate complete system performance and specification compliance.
Functional Test Validation Areas
| Validation Area | Test Parameters | Example Tests |
| Power Management | Voltage levels, current draw, power sequencing | Rail voltage accuracy, inrush current, brown-out recovery |
| Firmware/Software | Boot sequence, memory integrity, OS functionality | Boot loader verification, RAM/ROM tests, driver validation |
| System Interfaces | Communication protocols, data integrity, timing | UART, I2C, SPI, USB, Ethernet protocol compliance |
| Signal Integrity | Waveform quality, sensor response, analog performance | ADC/DAC linearity, sensor calibration, noise floor measurement |
| Environmental Simulation | Operation under temperature extremes | High/low temperature functional testing |
Methodology: Custom test stations with application-specific software
Outcome: Go/no-go determination of final product readiness
7. Integrated Quality Assurance System
Our testing methodology represents a connected quality ecosystem rather than isolated inspection steps:
- Process Prevention: SPI prevents defects at the source with real-time feedback.
- Visual & Hidden Defect Detection: AOI and X-Ray catch assembly defects post-reflow.
- Electrical Verification: ICT or Flying Probe validate manufacturing correctness.
- System Validation: Functional Test guarantees specification compliance.
Data Analytics & Continuous Improvement
- Statistical Process Control (SPC): Real-time monitoring of test data for process capability analysis.
- Overall Equipment Effectiveness (OEE): Tracking of equipment utilization and performance metrics.
- Defect Trend Analysis: Identification of recurring issues for root cause investigation.
- First Pass Yield (FPY) Monitoring: Continuous tracking of quality performance metrics.
Compliance & Standards
Our testing processes adhere to international quality standards including:
- IPC-A-610: Acceptability of Electronic Assemblies
- IPC-9201: Surface Insulation Resistance Handbook
- IPC-9252: Guidelines for Electrical Testing of Unpopulated Printed Boards
- ISO 9001:2015 Quality Management Systems
- IEC 61189-5: Test methods for electrical materials, printed boards and other interconnection structures and assemblies
This comprehensive testing and inspection strategy ensures we deliver defect-free, reliable printed circuit board assemblies that meet the most stringent quality requirements for automotive, medical, industrial, and consumer applications.
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