Cutting printed circuit boards (PCBs) from larger panels is an essential step in PCB fabrication and assembly. PCB manufacturers rely on dedicated cutting tools to singulate individual boards or assembly panels from panelized arrays cost-effectively and accurately. The two main options are manual PCB shears and automated PCB cutting machines.
Selecting the right PCB cutting method requires evaluating key factors like cut quality, throughput, cost, complexity, and capabilities for the types of boards and volumes to be processed. This article provides a detailed comparison between manual PCB shears and automated cutting machines to help guide the optimal equipment choice.
Overview of PCB Shears
PCB shears are manually-operated tools used to cut circuit boards by applying mechanical shear force. Key features include:
- Blade Style – Straight or slant blade options exist. Slant creates scissor-like shearing.
- Actuation – Spring, air, electric, or hydraulic pressure closes blades.
- Capacity – Various tool sizes cut boards up to 0.8in (20mm) thick.
- Accuracy – Depends on operator skill. Fixtures can aid positioning.
- Speed – Manual process limits speed versus automation.
- Cost – Lower equipment cost in the $3k to $10k range.
PCB shears are a simple, low cost cutting option but require skilled operators for consistent quality and throughput.
PCB Shearing Process
Using PCB shears for cutting involves the following key steps:
The PCB panel is positioned in the shear based on measurement marks or fixtures. Proper alignment is critical.
Clamps hold the board securely in position during cutting to prevent shifting.
The operator manually squeezes the shear handle to close the blades through the board with precise downwards pressure.
The board is manually indexed to the next cut location and aligned. Fixtures aid repeated positioning.
Cutting strokes are repeated according to panel layout to singulate all required boards. Deburring removes sharp edges.
Shear Cut Quality Factors
Several factors impact the cut quality and consistency using PCB shears:
- Operator skill and training
- Tool sharpness and precision
- Clamping force and stability
- Blade type (straight, slant, double)
- Cutting stroke consistency
- Fixtures and precision measurement
- Deburring process
Dedicated tools like perforated or scored cut lines aid shear positioning. But ultimately the operator controls key variables influencing cut quality like pressure and alignment.
Benefits of PCB Shears
PCB shears have some compelling benefits that make them a cost-effective cutting solution:
Low Equipment Cost
- Shears are an inexpensive cutting tool option with prices from a few thousand dollars.
- Basic manually actuated operation with no complex mechanics or programming.
- Minimal setup time to start cutting different board designs and sizes.
- Compact tabletop footprint takes minimal floorspace.
- Operators can adapt on the fly to handle small volume panel variations.
- No complex machinery to maintain. Just blade sharpening and replacement.
For low to moderate production volumes, PCB shears can offer an economical cutting solution when paired with an experienced operator.
Limitations of Manual PCB Shears
While useful in some scenarios, PCB shears have some distinct limitations:
- Cut quality depends heavily on operator skill and fatigue level.
- Manual process limits speed and volume.
Higher Labor Cost
- Intensive labor cost for skilled operators over long shifts.
- Shear blades produce wider cut channels versus precision machining.
- Deburring adds additional manual processing step.
- Harder to integrate shears into automated material handling flows.
For cutting high volumes or complex board designs, manual shears become less viable both technically and economically.
When to Use PCB Shears
Here are typical production situations where PCB shears may be the preferred option over automated machines:
- Low to medium volumes (<5,000 boards per week)
- Lower complexity boards and materials
- Frequent design changeovers
- Lower cut quality requirements
- Tight budget constraints
- Minimal available floorspace
Overview of Automated PCB Cutting Machines
Automated PCB cutting utilizes computer-controlled machines to cut boards based on programmed tool paths. Common machine architectures include:
- Use a rotary end mill tool spinning at high RPM to cut boards.
- Cut with an actuated vertical knife blade mounted to X-Y gantries.
- Directed laser beam ablates material to cut complex shapes and profiles.
- High pressure waterjet quickly cuts contours in boards.
Automated cutting machines offer much higher throughput, precision, consistency, and capabilities versus manual shears. But the equipment cost is also far higher.
Automated PCB Cutting Process
Here is an overview of the typical automated cutting sequence:
Tool Path Programming
The required cut pattern is defined in software based on board panel sizes, orientations, and finished board dimensions.
Panels are automatically loaded onto the machine bed from a conveyor or stack. Vacuum holds boards in place.
Fiducials on the panel are detected by cameras to precisely align boards for accurate cutting.
Conveyors remove finished cut boards and scrap from the machine. Optional sorting can separate boards and scrap.
Automated or manual inspection verifies cut quality. Precision cutting minimizes need for extensive verification in high volume applications.
Technical Attributes of Automated Cutting
Automated PCB cutting machines enable significant enhancements across these technical metrics:
- Tight tolerances down to +/- 0.10mm achieved from programmed tool paths and precision stages.
- Automated process varies minimally across thousands of boards.
- Very smooth edge finish with minimal debris. Controlled cutting parameters optimize edge quality.
- Reduced kerf width as low as 0.15mm conserves material.
- Cut rates from 10 to over 100 boards per hour depending on size and complexity.
- Proven machine designs for continuous operation with high uptime.
- Seamless integration into automated material flows between processes.
These technical capabilities enable cutting high complexity boards at mass production volumes.
Economic Benefits of Automated Cutting
In addition to technical advantages, automated PCB cutting machines can provide compelling economic benefits:
- Dramatically reduce labor by eliminating manual cutting steps.
- Consistent precision cutting minimizes panel waste from cut defects.
- Cut more boards per day with faster cycle times.
- Easily scale to higher volumes by running machines longer or adding machines.
- Lower cost per cut board through labor savings and efficiency gains.
- Switch between different board designs with minimal downtime.
For medium and higher volume production, automated cutting machines improve quality while reducing overall PCB fabrication costs.
Considerations for Automated PCB Cutting
Here are some factors to consider when implementing automated board cutting:
- Machines ranging from $50k to over $500k with advanced software, tooling, and accessories.
- Requires CAM programming expertise to generate machine-specific cut patterns.
- Must budget for machine maintenance and occasional repairs.
- Machines have larger footprint than shears and may require special facilities.
- Still need qualified technicians to oversee machines and quality.
- Some minor changeover and programming required when switching board designs.
When to Use Automated Cutting Machines
Here are typical high volume production scenarios where automated PCB cutting machines become advantageous:
- Cutting over 5,000 PCBs per week
- Complex board shapes or profiling required
- Advanced materials like flex or rigid-flex
- Cut tolerances under 0.20mm required
- High mix of different board designs
- Integration into automated material handling flows
- Continuous mass production operation
PCB Shears vs. Automated Cutting Comparison
|Factor||PCB Shears||Automated Cutting Machine|
|Equipment Cost||$3k – $10k||$50k – $500k+|
|Cut Speed||2 – 10 boards/min||10 – 200+ boards/min|
|Cut Precision||+/- 0.25mm||+/- 0.10mm or better|
|Complexity||Simple shapes only||Complex contours and profiling|
|Changeover||< 5 min||< 15 min|
|Labor||High manual labor||Low semi-automated|
For some manufacturers, a hybrid approach combining both manual shears and automated cutting provides the right balance:
- Shears for low volume flex or rigid-flex jobs
- Shears for prototyping and short runs
- Machines for higher volume production
- Shears for overflow capacity
This hybrid model allows optimizing the strengths of each technology for different needs.
Recommendations for Selecting PCB Cutting Methods
Based on key parameters and tradeoffs between PCB shears and automated cutting machines, here are some best practice recommendations:
Low Volume Cutting
For low volume PCB cutting under 5000 units per week, with less demanding quality and simple board shapes, manually operated PCB shears provide the most cost-effective solution.
High Volume Cutting
For cutting volumes over 5000 PCBs per week, tighter cut tolerances, and complex board shapes, automated cutting machines will deliver superior quality at lower overall cost.
High Mix Production
In facilities with high mix production across both low and high volume boards, a hybrid approach with both shears and cutting machines allows optimizing the cutting strategy for each job.
Thoroughly evaluate PCB shears vs. machine cutting capabilities against current and future requirements to avoid overbuying or underbuying equipment. Involve staff in assessing impact on labor, quality, and total cost.
Both PCB shears and automated cutting machines have their place in PCB fabrication workflows depending on volumes, design complexity, available labor, floorspace, and budget constraints. Carefully weighing technical capabilities, productivity, and economics will lead to selecting the optimal cutting solutions. A combination of manual and automated options provides maximum manufacturing flexibility. As demands grow, adding automated precision cutting machines supports cost-effectively scaling to higher production levels while maintaining quality.
Frequently Asked Questions
Q: How are perforated or scored lines used in PCB shearing?
A: Perforated or scored lines on the panel help guide the operator during shearing by defining cut locations, improving positioning accuracy.
Q: Can PCB shears effectively cut rigid-flex boards?
A: Shears can cut simple rigid-flex boards but automated machines offer better control of cutting through multiple material zones.
Q: What safety precautions should be used with PCB shears?
A: Safety glasses, cut-resistant gloves, and finger guards should be worn. Avoid loose clothing. Maintain sharp blades.
Q: How are curved or contoured board shapes cut?
A: Automated machines with interpolation capabilities are required for profiling complex board outlines versus simple straight line shearing.
Q: How are PCB shears maintained and adjusted?
A: Follow manufacturer instructions for lubrication, blade inspection, sharpening, and calibration. Replace worn blades for best cut quality.