Stock control and attrition in surface mount assembly are important aspects of managing electronic manufacturing processes. When purchasing parts for low quantity prototype boards that are hand soldered, it’s unlikely you will need to worry about attrition. However, when manufacturing medium to high volumes of a board, it is crucial to take attrition into account. Overlooking attrition can cause delays in assembly while more parts are sourced and delivered.
During SMT manufacture, components will be lost in a number of unavoidable ways. Loading the components onto the feeders is one of the main causes of component loss. Most Pick and Place machines require a certain length of leader tape to be fed into a feeder in order for the feeder to work effectively. Where part reels are supplied, and no leader is included, then a leader has to be made by losing/wasting the first few inches of components on the tape.
Another cause of ‘lost’ components is mis-picks by the pick and place machine. Mis-picks are where the machine cannot pick the component from the tape (for which there are a number of possible causes). The smaller the component the more chance there is of a mis-pick.
Determining the excess amount (attrition) is not always easy - The levels will vary depending on the size, type, price and packaging of the component, but below are some rough guides for attrition:
• Passive components (e.g. resistors, capacitors, inductors): 5-15%
• Active component (e.g. IC’s, transistors, power sources): 3-5%
• High value components (e.g. processors, BGA’s, memory): 1 spare component per order
To reduce the loss of components at manufacture, it’s important to consider how the components are supplied. Buying components on reels or in large continuous strips of cut tape, rather than multiple short strips or loose, means less will be lost at the setup of the PP machine. Utilising full reels or larger continuous strips can also enable you take advantage of substantial price breaks. Any excess components not ‘wasted’ during manufacture will either be returned to the customer or used on subsequent production runs.
The cost of attrition tends to be very high for low volume runs (1 -10 boards) with attrition contributing to around 5-20% of the material cost. Higher volume runs see this percentage drop away to less than 1% for runs of >100 boards. When considering attrition levels for components, it is best to overestimate as the cost associated with buying a few extra parts can often be far less than the cost of stopping the production line, and all the delays this entails. Of course, counter to this, it is important to not set your attrition levels too high, else the upfront cost of manufacturing could make the cost/board prohibitively high to manufacture.
During SMT manufacture, components will be lost in a number of unavoidable ways. Loading the components onto the feeders is one of the main causes of component loss. Most Pick and Place machines require a certain length of leader tape to be fed into a feeder in order for the feeder to work effectively. Where part reels are supplied, and no leader is included, then a leader has to be made by losing/wasting the first few inches of components on the tape.
Another cause of ‘lost’ components is mis-picks by the pick and place machine. Mis-picks are where the machine cannot pick the component from the tape (for which there are a number of possible causes). The smaller the component the more chance there is of a mis-pick.
Determining the excess amount (attrition) is not always easy - The levels will vary depending on the size, type, price and packaging of the component, but below are some rough guides for attrition:
• Passive components (e.g. resistors, capacitors, inductors): 5-15%
• Active component (e.g. IC’s, transistors, power sources): 3-5%
• High value components (e.g. processors, BGA’s, memory): 1 spare component per order
To reduce the loss of components at manufacture, it’s important to consider how the components are supplied. Buying components on reels or in large continuous strips of cut tape, rather than multiple short strips or loose, means less will be lost at the setup of the PP machine. Utilising full reels or larger continuous strips can also enable you take advantage of substantial price breaks. Any excess components not ‘wasted’ during manufacture will either be returned to the customer or used on subsequent production runs.
The cost of attrition tends to be very high for low volume runs (1 -10 boards) with attrition contributing to around 5-20% of the material cost. Higher volume runs see this percentage drop away to less than 1% for runs of >100 boards. When considering attrition levels for components, it is best to overestimate as the cost associated with buying a few extra parts can often be far less than the cost of stopping the production line, and all the delays this entails. Of course, counter to this, it is important to not set your attrition levels too high, else the upfront cost of manufacturing could make the cost/board prohibitively high to manufacture.
Stock Control:
Stock control in surface mount assembly is a critical aspect of managing electronic manufacturing processes efficiently. It involves the management of inventory and components required for the surface mount assembly process. Effective stock control helps minimize costs, reduce waste, and ensure that the necessary materials are available when needed. Here are key considerations and strategies for stock control in surface mount assembly:
Effective stock control in surface mount assembly ensures that you have the right components at the right time, minimizes waste, and optimizes costs, contributing to the overall success of electronic manufacturing operations.
- Just-in-Time (JIT) Inventory:
- Implement a JIT inventory system to minimize excess inventory and carrying costs. In a JIT system, components are ordered and stocked only as needed for production, reducing the risk of overstocking or obsolescence.
- Forecasting and Demand Planning:
- Use historical data, production forecasts, and market demand to predict component requirements accurately.
- Collaborate with suppliers to improve lead times and flexibility in responding to fluctuations in demand.
- ABC Analysis:
- Categorize components into "A," "B," and "C" groups based on their importance, usage, and cost.
- Allocate more attention and control to "A" items, which are critical to the assembly process, while managing "C" items with less rigor.
- Vendor Management:
- Establish strong relationships with component suppliers. Good relationships can lead to better pricing, faster deliveries, and more reliable quality.
- Consider vendor-managed inventory (VMI) or consignment stock arrangements to optimize component availability.
- Minimize Excess Stock:
- Regularly review and adjust stock levels to avoid overstocking and obsolescence. Use first-in, first-out (FIFO) or last-in, first-out (LIFO) methods as appropriate.
- Implement a controlled release process for new components to avoid stockpiling.
- Barcode and RFID Tracking:
- Implement tracking systems using barcodes or RFID technology to monitor the movement of components within the manufacturing facility. This provides real-time visibility into inventory levels and helps prevent loss or misplacement.
- Kanban Systems:
- Use Kanban systems or visual cues to signal when it's time to reorder components. This approach is particularly effective for managing low-volume, high-mix assembly processes.
- Safety Stock:
- Maintain a buffer of safety stock for critical components to account for unexpected demand fluctuations, supplier delays, or quality issues.
- Cycle Counting:
- Regularly conduct cycle counts to verify the accuracy of inventory levels and correct any discrepancies promptly.
- Materials Handling:
- Implement proper materials handling practices to prevent damage or contamination of components during storage and transportation.
- Use antistatic packaging for sensitive electronic components.
- Inventory Management Software:
- Invest in inventory management software that provides real-time tracking, reporting, and analytics to help optimize stock levels and improve overall control.
- Obsolescence Management:
- Monitor the lifecycle of components and plan for end-of-life (EOL) or obsolescence issues. Work with suppliers to find suitable replacements and reduce the risk of shortages.
- Continuous Improvement:
- Regularly review and refine stock control processes based on performance data and changing requirements.
- Regularly review and refine stock control processes based on performance data and changing requirements.
Effective stock control in surface mount assembly ensures that you have the right components at the right time, minimizes waste, and optimizes costs, contributing to the overall success of electronic manufacturing operations.
Component attrition:
Component attrition in surface mount assembly refers to the loss, damage, or wastage of electronic components during the assembly process. Reducing component attrition is crucial for minimizing production costs, improving product quality, and ensuring that the assembly process is efficient and reliable. Here are some common causes and strategies to control component attrition in surface mount assembly:
Causes of Component Attrition:
- Mishandling: Components can be damaged if mishandled by assembly operators. This includes dropping, crushing, or improperly storing components.
- Electrostatic Discharge (ESD): Electrostatic discharge can damage sensitive electronic components. Components may discharge static electricity when handled improperly.
- Pick-and-Place Errors: Errors in the automated pick-and-place process can lead to component misalignment, tombstoning (one end of the component lifts off the PCB), or incorrect placement.
- Soldering Issues: Inadequate or excessive solder paste, incorrect reflow profiles, or contaminated solder paste can result in soldering defects and component damage.
- Moisture Sensitivity: Some components are moisture-sensitive and may suffer from delamination or popcorning if exposed to moisture during the assembly process.
- Component Mismatch: Errors in component identification and handling can lead to the use of incorrect components, resulting in attrition.
Strategies to Control Component Attrition:
- Quality Control and Inspection:
- Implement thorough quality control and inspection procedures at various stages of the assembly process, including incoming inspection of components and inspection during placement.
- Operator Training:
- Provide comprehensive training to assembly operators to ensure they handle components correctly and follow best practices.
- ESD Protection:
- Create an ESD-safe environment with ESD-safe workstations, equipment, clothing, and grounding measures to prevent ESD-related damage.
- Proper Material Handling:
- Implement proper handling, storage, and transportation practices to prevent mechanical damage to components. Use ESD-safe packaging and containers.
- Automated Assembly:
- Use automated pick-and-place machines and reflow ovens to reduce the risk of errors and damage caused by manual handling.
- Environmental Control:
- Maintain a controlled environment with stable temperature and humidity levels to prevent moisture-related issues.
- Component Inspection and Verification:
- Utilize vision inspection systems to check component orientation, presence, and quality before placement.
- Implement component verification processes to confirm the correct components are loaded onto feeders or pick-and-place machines.
- Failure Analysis:
- Analyze and document the causes of component attrition when it occurs. Use this data to identify root causes and areas for improvement.
- Inventory Management:
- Maintain an organized inventory of components to prevent damage or misplacement, and implement procedures to avoid mixing components with similar packaging or markings.
- Continuous Improvement:
- Foster a culture of continuous improvement by collecting and analyzing data on attrition rates. Use this information to identify trends and areas for enhancement.
- Foster a culture of continuous improvement by collecting and analyzing data on attrition rates. Use this information to identify trends and areas for enhancement.
By implementing these strategies and maintaining a strong focus on quality control and process improvement, you can effectively control component attrition in surface mount assembly, resulting in reduced waste, higher product quality, and cost savings.
SMT component attrition control in ERP software:
To control SMT (Surface Mount Technology) component attrition using ERP (Enterprise Resource Planning) software, you can utilize various modules and features within your ERP system to manage inventory, track component usage, and monitor attrition. Here are steps to effectively control SMT component attrition within an ERP system:
- Inventory Management:
- Use the ERP's inventory management module to keep track of all electronic components in stock. Set up clear categories and attributes for each component, including part numbers, suppliers, and key technical specifications.
- Real-Time Monitoring:
- Implement real-time monitoring of component usage and attrition through automated data capture. Utilize barcode scanning or RFID technology to track when components are used and returned to inventory.
- Component Classification:
- Classify components based on their criticality and sensitivity to attrition. This classification can be used for prioritizing controls and monitoring.
- Alerts and Notifications:
- Set up alerts and notifications in your ERP system to trigger when components are nearing their shelf life, have low stock levels, or when unusual attrition patterns are detected.
- Attribute Tracking:
- Use ERP software to track component attributes that are prone to attrition, such as moisture sensitivity, ESD sensitivity, and shelf-life information. Incorporate these attributes into the component data.
- Quality Control Data Integration:
- Integrate quality control data from inspection and testing processes into your ERP system. This data can include information on component defects or damage, helping to identify and address attrition issues.
- Defect Analysis:
- Use the ERP system to collect and analyze data on component attrition, including the causes of defects or damage. This can be valuable in identifying trends and areas for improvement.
- Reporting and Analytics:
- Leverage the reporting and analytics capabilities of your ERP software to generate attrition-related reports. These reports can include attrition rates, trends, and root cause analysis.
- Workflows and Standard Operating Procedures:
- Implement workflows and standard operating procedures within the ERP system that guide operators and staff in handling components and maintaining an attrition-controlled environment.
- Supplier Collaboration:
- Use the ERP system to collaborate with component suppliers. Establish communication channels for sharing attrition-related data and receiving timely information on component changes, recalls, or quality issues.
- Replenishment and Ordering:
- Set up automated replenishment triggers in your ERP system to ensure that stock levels are maintained at optimum levels, minimizing the risk of attrition due to shortages.
- Employee Training and Certification:
- Use the ERP system to track and manage employee training and certification in areas related to component handling, ESD control, and quality assurance.
- Audit Trails:
- Maintain comprehensive audit trails of all component-related transactions within the ERP system, allowing for traceability and accountability.
- Continuous Improvement:
- Implement a process within your ERP system for continuous improvement, including periodic reviews of attrition data and the implementation of corrective actions.
- Implement a process within your ERP system for continuous improvement, including periodic reviews of attrition data and the implementation of corrective actions.
By leveraging your ERP software for SMT component attrition control, you can centralize data and processes, improve visibility, and enhance your ability to manage inventory effectively, reduce attrition, and maintain the quality and reliability of your electronic assembly process.
X-ray component counting for SMT components on tape and reel when kits are issued to production/returned to stock for attrition control:
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Implementing X-ray component counting for SMT components on tape and reel when kits are issued to production and returned to stock is a comprehensive approach to attrition control. This process helps ensure that components are accurately counted, properly aligned, and free from damage when transitioning between inventory and production. Here's how you can integrate X-ray counting into this workflow:
Issuing Kits to Production:
Returning Kits to Stock:
By integrating X-ray component counting into the workflow for issuing kits to production and returning them to stock, you can enhance accuracy, reduce attrition, and maintain a high level of control over component quality throughout the manufacturing process. This approach contributes to improved product quality and production efficiency.
Issuing Kits to Production:
- Preparation of Kits:
- Before issuing kits to production, components should be carefully selected, and their quantities verified in the inventory management system. Ensure all components are properly labeled.
- Tape and Reel Handling:
- Use dedicated equipment or trained personnel to handle tape and reel packaging. This minimizes the risk of component mishandling.
- X-ray Inspection:
- As kits are prepared for production, the tape and reel packages can be subjected to X-ray inspection. This inspection should verify the correct count and alignment of components.
- Data Logging and Verification:
- The X-ray system should log inspection results, including the number of components counted. These results can be verified against the kit's bill of materials (BOM) to ensure accuracy.
- Production Authorization:
- Only issue kits to production once the X-ray inspection confirms that components are accurate and free from defects.
- Recording and Traceability:
- Record the X-ray inspection results and kit issuance in the ERP or inventory management system, ensuring full traceability.
Returning Kits to Stock:
- Unconsumed Components:
- When production is complete, any unconsumed components in the kits should be handled with care and returned to inventory.
- Tape and Reel Inspection:
- Inspect the tape and reel packaging with X-ray before returning components to stock. This step helps ensure that no components were damaged during production.
- X-ray Analysis:
- Use the X-ray system to count the components and verify their alignment in the tape and reel packaging.
- Data Logging and Verification:
- Log inspection results and verify them against the expected counts. This helps ensure the components are returned to inventory accurately.
- Stock Update:
- Update the inventory management system to reflect the accurate counts and condition of components returned to stock.
- Disposition of Damaged Components:
- If any damaged components are detected during X-ray inspection, properly disposition them following your company's procedures. This might include documenting the damage and quarantining affected components.
- Continuous Improvement:
- Use data from the X-ray inspections to identify trends or issues related to component attrition. Implement process improvements as needed to minimize attrition.
By integrating X-ray component counting into the workflow for issuing kits to production and returning them to stock, you can enhance accuracy, reduce attrition, and maintain a high level of control over component quality throughout the manufacturing process. This approach contributes to improved product quality and production efficiency.
