Lead-free Impact on X-ray Inspection


With the July 2006 deadline for the European Union’s (EU’s) RoHS and WEEE directives past, it’s interesting to observe the long-term impact of lead-free implementation upon X-ray inspection. Not everyone has taken up the lead-free challenge, and for those who have, there is a continuous need for vigilance and proof of process quality to the final customer. As a result, X-ray inspection has moved from being simply about confirming process quality to proving process quality to end-customers if compliance problems should arise. Having X-ray inspection on-site means the cause of these problems can be traced more quickly to the correct solution, instead of just pointing the finger at a BGA device, because the reflow quality cannot be proven without it.

As lead-free becomes more dominant, there are many component issues waiting on the horizon. Confusion with component labeling will result in problems with non-lead-free components failing under the increased temperatures of lead-free processes.

The ability to confirm the incoming component quality using non-destructive means is becoming more important not only to eliminate components as the source for process problems, but also to look for counterfeit components, an increasing concern. This may be achieved with X-ray inspection by looking at the die-attach quality of the incoming components, or the quality and effectiveness of the wire bonding within the package.

The use of multiple stacked die within packages, package-in-package (PiP), and package-on-package (PoP) arrangements requires higher resolution and higher quality X-ray imaging to be able to confirm package quality prior to SMT placement and thermal processing.

Market trends indicate increased BGA usage combined with a corresponding reduction in pitch and solder ball diameter. The use of flip chips is also foreseen to increase, again with a reduction in bump size and pitch, with bump sizes going substantially below 100 µm in diameter.

The further use of PiP and PoP products will result in an increasing number of hidden joints to inspect. With many of these interconnections obscured by other hidden joints within the package, a greater demand will be placed on X-ray inspection.


In the electronics industry, volume production will continue to migrate to lower cost labor regions. Substantial growth in countries such as India and Vietnam, as well as in Eastern Europe, including Poland and Romania, has already begun. Local labor costs will begin to rise as the migration cycle continues to the next less-expensive area. This leads remaining manufacturers to add value by becoming niche players as a survival strategy.

With X-ray inspection, new operators will have to be trained continually in X-ray test and inspection techniques. Established markets will require a higher level of X-ray sophistication to verify and improve quality, and to differentiate OEMs from their higher value-add competitors.

Mobile phones will continue to drive technological and volume factors within the industry, especially as the convergence of phone, e-mail, PDA, Internet services, and video-on-demand continues. This will drive X-ray capabilities, as components shrink while increasing in complexity, such that X-ray inspection technology is developed to support the industry.


X-ray inspection technology faces many challenges even as miniaturization drives many products smaller. Making X-ray inspection easier to use will be essential so that it can migrate further into the production process as opposed to simply being a failure-analysis tool.

The ability to inspect smaller features and to look for smaller faults in these features will drive the need for greater resolution of X-ray imaging. More automation of the inspection process and increased analysis will help the consistency and volume of inspection to take place and that will drive the customers’ quality upward.

As the need for X-ray inspection continues to increase within the production process, so will the the requirements for X-ray equipment. X-ray inspection will be required as part of an assembly line, much as automated optical inspection (AOI) is used today.

Increasing process requirements and product complexity are making X-ray inspection vital to quality production. X-ray manufacturers must observe the prevailing trends and develop inspection technology solutions ahead of market requirements.

Click here to enlarge image

PAUL WALTER, managing director, may be contacted at Dage Precision Industries, Inc., 4024 Clipper Court, Fremont, CA 94538; 510/683-3930; E-mail: [email protected].


Easily post a comment below using your Linkedin, Twitter, Google or Facebook account. Comments won't automatically be posted to your social media accounts unless you select to share.