BGA Inspection using X-Ray
SMT/BGA Inspection - precision images for advanced assembly
Many manufacturers of advanced SMT assemblies rely on Glenbrook’s real-time x-ray inspection technology to evaluate solder joint integrity for BGAs and other leadless packages that cannot be inspected by conventional vision systems.
For assemblers who measure BGA solder voids to determine quality, Glenbrook’s patented x-ray camera offers a unique advantage: it is the only system not subject to Voltage Blooming. Void sizes remain consistent at all voltages, providing reliable pass/fail data.
As an alternative to large packages with high pin counts, ball grid arrays (BGAs) have distinct benefits: smaller size, lower inductance, reduced coplanarity and lack of skewing. But once a BGA is placed, how can the integrity of its solder bond be measured?
Many manufacturers of advanced SMT assemblies rely on Glenbrook's real-time x-ray technology to evaluate solder joint integrity for BGAs and other leadless packages that cannot be inspected by conventional vision systems. In the course of working with our systems, these manufacturers have verified a fundamental principle of productive assembly: it's more effective to inspect the process, rather than the product.
Real-time x-ray inspection helps to establish quality as an integral part of your process, right from the start, and to maintain it throughout your line, for BGA evaluation or any other aspect of the process. In the development stage, real-time x-ray inspection defines the optimal parameters required to maintain a process in control. During production audits, it ensures that those parameters are being maintained.
Advantages of the Glenbrook System for the Inspection of BGAs
Since solder voids in Ball Grid Array (BGA) solder bonds are easily detected with x-ray inspection, they are usually classified, without a clear understanding, as defects. Subsequent studies however have shown that some solder voids actually improved the reliability of the solder bond. The question then remains as to what level of solder void is acceptable. This issue is addressed in detail in the IPC Standard 7095, “Design and Assembly Process Implementation for BGAs.”
In this standard, there is a cautionary note regarding the tendency of many of the commercial x-ray inspection systems in use, to exaggerate or distort the size of the void. This type of distortion will occur only if the type of x-ray imaging device used in the particular system suffers from “Voltage Blooming.” Glenbrook x-ray camera technology does not exhibit this “Voltage Blooming” distortion of the image.
Voltage BloomingIn the example of voltage blooming shown at below, the first x-ray image has been made at 50 kV, the second at 60 kV. As can be seen, the white areas of the void are artificially exaggerated by increased voltage when the x-ray camera used suffers from this defect. |
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 50 kV |
 60 kV |
To support SMT/BGA inspection, Glenbrook offers products for process development and quality assurance:-
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In March 2010 The SMART Group carried out a poll of it's members asking"BGA inspection, which procedure do you most commonly use in your company?". The results of which show that over 50% of members use x-ray as at least part of their inspection procedures. So, if you are not yet using x-ray Glenbrook Technologies offer a great value route to add this capability to your business. The full survey results can be seen here SMART BGA Inspection survey.
For more information about BGA applications for real-time x-ray inspection, see the articles on our Technical Papers page or call TestSolve on 01494 449677.
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