Submitting correct and complete files is essential for fast and accurate PCB assembly. Missing or incorrect data often leads to delays, extra costs, and manufacturing errors.
In this guide, TOPFAST, a professional PCB manufacturer, explains all PCB assembly file requirements, how each file is used, and how to prepare them correctly.
Table of Contents
Why PCB Assembly Files Matter
Accurate files help manufacturers:
- Understand your design intent
- Prevent assembly errors
- Shorten the lead time
- Reduce engineering questions
Well-prepared files enable smooth turnkey PCB assembly.
Related guide:
What Is Turnkey PCB Assembly and How It Works
Required Files for PCB Assembly
Most PCB assembly manufacturers require the following files:
- Gerber files
- BOM (Bill of Materials)
- Pick-and-Place (CPL) file
- Assembly drawings (recommended)
Let’s review each one in detail.
Gerber Files
What Are Gerber Files?
Gerber files describe the physical layout of the PCB, including copper layers, solder mask, silkscreen, and board outline.
Typical Gerber Files Include:
- Top & bottom copper layers
- Solder mask layers
- Silkscreen layers
- Drill file
- Board outline
Best Practices:
- Use RS-274X format
- Clearly define layer polarity
- Ensure correct board outline
Related article:
PCB Manufacturing vs PCB Assembly
BOM (Bill of Materials)
What Is a BOM?
A BOM lists all components required for assembly.
A Complete BOM Should Include:
- Reference designator (e.g., R1, C2)
- Component description
- Manufacturer part number (MPN)
- Quantity
- Package type
- Alternative parts (recommended)
Common BOM Mistakes:
- Missing MPNs
- Inconsistent reference designators
- Outdated or obsolete parts
Accurate BOMs are critical for component sourcing in a turnkey PCBA.
Pick-and-Place (CPL) File
What Is a Pick-and-Place File?
The Pick-and-Place file (also called CPL or centroid file) tells assembly machines:
- Component coordinates
- Rotation angles
- Placement side (top/bottom)
CPL File Requirements:
- Correct origin point
- Accurate rotation values
- Consistent reference names
This file is essential for SMT PCB assembly.
Related article:
SMT vs THT PCB Assembly: Key Differences Explained
Assembly Drawings (Highly Recommended)
Although optional, assembly drawings greatly improve accuracy.
They can include:
- Component orientation notes
- Polarity markings
- Special assembly instructions
- THT or hand-soldering notes
Assembly drawings help reduce engineering questions.
Additional Files for Advanced PCBA
Depending on the project, manufacturers may also request:
- Test requirements or test programs
- Programming files
- Special process instructions
- Functional test specifications
Related guide:
PCBA Testing Methods Explained
File Checklist Before Submission
Before submitting files, verify:
- All reference designators match across files
- BOM quantities are correct
- CPL file aligns with Gerber layers
- Special instructions are clearly documented
This checklist helps ensure fast PCB assembly turnaround.
Common File-Related Issues in PCB Assembly
- Mismatch between BOM and Gerber
- Incorrect rotation angles
- Missing polarity indicators
- Incomplete BOM data
These issues can delay production if not addressed early.
File Requirements in Turnkey PCB Assembly
In turnkey PCB assembly, manufacturers rely heavily on accurate files to:
- Source correct components
- Optimize assembly flow
- Perform reliable testing
Related article:
PCB Assembly Services – Complete Turnkey PCBA Solutions
Why Choose TOPFAST for PCB Assembly?
As a professional PCB manufacturer, TOPFAST provides:
- Free file review before production
- DFM/DFA engineering support
- Clear communication on file issues
- Fast turnaround for prototypes and production
Well-prepared files combined with TOPFAST expertise ensure smooth PCBA production.
Conclusion
Correct PCB assembly files are the foundation of successful PCBA production. By preparing accurate Gerber, BOM, and Pick-and-Place files, customers can significantly reduce cost, risk, and lead time.
PCB Assembly File FAQ
A: All files are important, but BOM and CPL files are critical for assembly accuracy.
A: Minor issues can be corrected, but major errors cause delays.
A: Yes. Prototypes require the same file accuracy as production boards.
A: Yes. Alternatives reduce sourcing delays.
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