SMTA International Conference Proceedings


USE OF DIGITAL X-RAY IMAGING AS A PROCESS CONTROL TOOL FOR LEAD-FREE PWB ASSEMBLY

Author: David Bernard et al.
Company: Dage Precision Industries
Date Published: 9/26/2004   Conference: SMTA International


Abstract: As the deadlines get ever closer in Japan and Europe that will prohibit the use of lead-containing solders for printed wiring board (PWB) assembly applications, considering the transition to using lead-free materials during manufacture becomes increasingly vital. The effects on the PWB production process of having to introduce new lead-free solder material; needing higher reflow oven temperatures, an altered printing process and possible use of different board finishes, requires consideration of continuous process control monitoring.

For example, it has been observed that the new lead-free materials tend to exhibit higher levels of voiding than their tin/lead counterparts, which may impact in-field reliability. This is in addition to potential faults initially implementing a lead-free process may cause. To help ensure production quality control, x-ray inspection is often considered a crucial part the test regime. As a nondestructive technique, x-ray inspection can be used without needing to sacrifice any product, whilst also being able to see otherwise hidden flaws, such as voids within joints.

Recent developments in digital x-ray imaging have further enhanced the analytical capabilities of this technique, including the ability to see very subtle differences in similar-density materials. This paper will discuss and show what process control information digital x-ray imaging can provide to improve PWB assembly quality and reliability.

Key words: Lead-free, process, control, x-ray, inspection



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