The development comprises four modules each based on a different non destructive detection technique:- Automated Optical Imaging (AOI), Digital Radiography (DR), Thermography and Scanning Acoustic Microscopy (SAM). Although some of the techniques are already used in industry, with the exception of AOI, they are typically used offline and consequently can only be used to conduct batch tests with limited defect detection capability. Additionally, AOI is also currently limited to line-of-sight inspection and cannot be applied to hidden joints and devices/features (e.g. ball grid array packages, integrated passives and vias in multi-layer boards). Other defects, such as plastic encapsulated delamination and heat plane delamination, can only be detected reliably with SAM and active thermography.
"This is the first time that the combined benefits of the four techniques have been utilised in an in-line environment to enable a 100% defect detection coverage" said Dr Ian Nicholson, principal scientist at TWI Ltd. "Depending on any given PCB configuration that is to be inspected, the inspection modules have been designed for in-line flexibility from the outset so that they can be used independently of each other, together or interchanged to give the best results in terms of inspection coverage and inspection throughput" he added.
The work is as a result of a two year European Framework 6 project shared between 10 organisations with TWI as the lead partner. The partners plan to exploit the knowledge they have gained through the collaboration and commercialise the prototype modules within two years.
More information about the project and project partners can be found at http://www.microscan.eu.com