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Engineering Process

Pre-Production
PCB-A

PCB Assembly Review

For PCB Fabrication & Assembly (F+A) projects, our engineering workflow is executed in two structured stages.First, the bare PCB undergoes fabrication pre-production validation to ensure it meets design and manufacturing requirements. Once the boards are approved and manufactured, the project transitions into the PCB Assembly pre-production phase, where all component-related and assembly parameters are thoroughly verified.This two-level verification process ensures accurate placement, reliable soldering, and high-yield production before assembly begins.

Detailed Workflow

PCB Assembly Engineering Steps

1. Bill of Materials (BOM) Validation

The Bill of Materials (BOM) defines every component required for PCB assembly. A detailed BOM verification is essential to prevent placement errors and sourcing issues.

Component Package & Footprint Verification

Each listed component is validated against:

  • PCB footprint dimensions
  • Manufacturer package specifications
  • Pad layout compatibility

This ensures that the physical component matches the PCB land pattern, preventing misalignment, solder defects, or mounting issues.

Quantity & Data Consistency Checks

Our engineering system performs structured checks to detect:

Missing components
Duplicate entries
Incorrect part numbers
Incomplete specifications

Early identification of inconsistencies reduces production delays and eliminates assembly errors before manufacturing begins.

2. Pick & Place File (CPL) Verification

The Component Placement List (CPL), also known as the Pick & Place file, defines the exact location, layer, and orientation of each component.

Our engineering team validates this data to ensure seamless automated placement.

Layer Assignment

All components are reviewed to confirm correct placement on:

  • Top layer
  • Bottom layer

Incorrect layer mapping can result in placement failures or assembly delays.

Reference Designator Cross-Check

Cross-matched with the BOM to ensure:

  • Accurate component mapping
  • No mismatches between files
  • Complete alignment of design data

This significantly reduces automated placement errors.

Orientation & Polarity Verification

Special attention is given to polarized and sensitive components such as:

Diodes
LEDs
Integrated Circuits (ICs)
Electrolytic capacitors
Connectors

Rotation angles and polarity markings are verified to prevent functional failures caused by incorrect orientation.

3. Virtual Assembly & Design for Assembly (DFA) Analysis

Before physical assembly begins, we conduct a virtual assembly simulation using BOM and CPL data.

This digital validation identifies potential assembly risks and manufacturability issues in advance.

Package Consistency Review

We verify that:

  • Component package types match PCB footprints
  • Pad geometries support reliable soldering
  • Mechanical clearances meet assembly standards

This prevents placement conflicts and solder joint failures.

Component Spacing & Clearance Verification

Proper spacing between components is evaluated to:

Prevent solder bridging
Reduce short-circuit risks
Allow adequate airflow and heat dissipation
Enable easier inspection and rework if necessary

Optimized spacing improves long-term reliability and production yield.

Solder Paste & Stencil Validation

Solder paste application parameters are carefully reviewed to ensure:

  • Correct paste volume deposition
  • Proper stencil aperture sizing
  • Alignment accuracy with copper pads

Excess solder can cause bridging, while insufficient solder may result in weak or cold joints. Proper validation ensures consistent and reliable solder connections.

Solder Short Risk Assessment

Designs are checked for potential solder short risks caused by:

  • Fine-pitch components
  • Tight pad spacing
  • Inadequate mask clearances

Preventive adjustments are recommended before assembly begins.

Fiducial & Machine Vision

Fiducial markers are validated to ensure:

  • Accurate machine vision alignment
  • Reliable automated placement
  • Reduced pick-and-place detection errors

Proper fiducial positioning enhances assembly precision and throughput.