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Technical Cleanliness Assessments to Reduce Manufacturing Defects
This paper will detail a Contamination Assessment Protocol that conforms to the guidelines in VDA19 Part 2 which will not only enable areas with the highest risk of contamination to be targeted for improvement measures but will also provide documentary evidence of the effect of any such improvements.
Technical Paper
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Authored By:
Sheila Hamilton
Teknek
Scotland, United Kingdom
Summary
Modern vehicles contain a large amount of electronics and as this is a safety critical application a Zero Defect manufacturing policy needs to be implemented. Particulate contamination is the major cause of functional impairments in an electronics system. To achieve Zero Defects individual components such as PCBs are normally cleaned during and after manufacture and the level of cleanliness required for them to function properly is specified and tested.
The German automotive industry has developed a methodology which can be used to test the Technical Cleanliness of component parts, such as PCBs VDA19 Part 1. Inspection of Technical Cleanliness – Particulate Contamination for functionally relevant automotive parts. However in subsequent manufacturing steps there is a risk that the initially clean PCBs become contaminated through transportation, storage and assembly. If the finished system cannot be cleaned after assembly, there is a chance for the contamination to remain in the end product and impair its function.
VDA19 Part 2 was developed to prevent the generation of critical particles of contamination at sensitive areas of manufacture, to remove unavoidable particles and to protect components and assembled systems against the entry of particles from the environment.
While there is guidance in VDA19 Part 2 as to areas to consider for mitigating the risk of contamination, an easy, quick method of assessing the level of Technical Cleanliness in real time is required. This would identify areas where the potential risk of particle generation is high and also document the effect of steps taken to reduce the risk of particle generation in each of the areas within the production process.
This paper will detail a Contamination Assessment Protocol, developed using Contact Cleaning technology that conforms to the guidelines in VDA19 Part 2 which will not only enable areas with the highest risk of contamination to be targeted for improvement measures but will also provide documentary evidence of the effect of any such improvements.
While a microscope may be required for detailed analysis of the results, instant feedback from the Particle Capture Sheet is clearly visible. After detailed analysis of each Particle Capture Sheet the results are assembled into a matrix which provides a map of the contamination within the production environment at a specific point in time. This can be helpful in identifying the initial source of particular types of particles as they move through the production area.
This methodology is a quick easy way to assess levels of Technical Cleanliness using the results to implement improvement activities which reduce defects and improve productivity.
Conclusions
By utilising the proven principles and methodology of VDA19 Part 1, Qualified Roller Extraction Cleaning can overcome many of the downsides associated with its use in high volume SMT assembly lines.
- It can remove particles from every PCB passing down the assembly line reducing defects.
- It provides visual results in real time
- It significantly shortens the time to get a Technical Cleanliness number
- It does not require solvent, complex equipment or highly trained technicians
- It enables a Contamination Assessment Protocol in line with VDA19 Part2
- Particle Capture Sheets can easily be archived for future comparison
Initially Published in the SMTA Proceedings
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