The Test Connection, Inc.

This is an outstanding introduction to X-ray inspection and Computed Tomography (CT) technology, especially for anyone involved in electronics manufacturing, quality assurance, reliability engineering, or failure analysis of circuit card assemblies.

Traditional 2D X-ray systems have long been used to inspect hidden solder joints, BGAs, BTCs, QFNs, vias, and internal PCB structures that cannot be seen with optical inspection. CT technology takes this capability to the next level by capturing hundreds or even thousands of X-ray images at different angles and reconstructing them into a fully navigable 3D model of the assembly.

What makes CT so powerful is the ability to virtually “slice” through the PCB or PCBA layer by layer without destroying the product. Engineers can inspect internal solder voiding, barrel cracks, head-in-pillow defects, insufficient wetting, lifted leads, broken internal connections, and even structural concerns inside complex multilayer assemblies. CT allows analysis of issues that may pass electrical test initially but become long-term reliability failures in the field.

As electronics continue to become smaller, denser, and more complex, CT inspection is rapidly becoming a critical tool for aerospace, defense, automotive, medical, and other high-reliability industries where failure is simply not an option.

A special recognition to Creative Electron, a true leader in the X-ray and CT inspection space. Bill Cardoso and the entire Creative Electron team are second to none when it comes to advancing inspection technology, supporting the electronics manufacturing industry, and helping companies improve quality and reliability through innovative imaging solutions.

At The Test Connection, Inc. (TTCI), we continue to see tremendous value in combining electrical test methodologies with advanced X-ray and CT inspection to create a more complete quality and reliability strategy for modern electronics manufacturing.

If you are attending this years SMTA Capital Expo make sure to stop by and ask Troy Johnson about our modular X-ray inspection system. Creative Electron’s modular platform is designed to grow alongside changing production demands with scalable CT capabilities, AI-driven inspection tools, and flexible workflows that adapt as products evolve. Whether you’re focused on improving quality, increasing process confidence, or preparing for next-generation designs, stop by The Capital Expo and connect with Troy to see how advanced inspection technology is reshaping electronics manufacturing.

Understanding the Anatomy of a QFN Package

As electronic assemblies continue to become smaller, faster, and more power-dense, package technology plays a critical role in both manufacturing reliability and long-term field performance. One package style that has become extremely common across aerospace, defense, medical, automotive, and commercial electronics is the Quad Flat No-Lead (QFN) package. While compact and electrically efficient, QFN devices also introduce unique manufacturing, inspection, and test challenges that must be understood early in the design and production process.

A QFN package is designed with exposed thermal pads, perimeter terminals, internal wire bonds, and a lead frame structure that provides excellent electrical and thermal performance. The compact footprint reduces parasitic inductance and resistance, making the package ideal for high-speed digital, RF, and power-management applications. However, the same features that improve electrical performance can also create hidden solder joints and inspection limitations that require careful manufacturing controls.

At The Test Connection, Inc., we evaluate QFN assemblies from both a manufacturing and test engineering perspective. During process development and production support, we focus heavily on solder joint integrity, thermal pad solder coverage, voiding levels, coplanarity, wetting performance, and PCB land pattern design. Since many QFN solder joints are partially or fully hidden beneath the package body, traditional visual inspection alone is often insufficient. This is why X-ray inspection, electrical test coverage analysis, and Design for Test (DfT) practices become extremely important.

One of the most critical areas of concern is the large exposed thermal pad located underneath the component. This pad provides heat dissipation and grounding, but excessive solder volume or poor stencil design can create component float, solder voiding, opens, or insufficient side fillets. Thermal via design beneath the package also directly impacts solderability, heat transfer, and assembly yield. Poor via structures may wick solder away from the pad or create inconsistent thermal performance during reflow.

From a test engineering standpoint, QFN packages can create significant accessibility challenges for In-Circuit Test (ICT) and Flying Probe Test (FPT). Because the leads terminate underneath or along the edge of the package, direct probing access may be limited or unavailable. This requires careful DfT planning during PCB layout to ensure critical nets remain electrically accessible for validation, boundary scan, functional verification, and fault isolation. Without proper DfT considerations, troubleshooting failures later in production can become time-consuming and expensive.

Inspection strategy is equally important. Automated Optical Inspection (AOI) may only provide partial visibility depending on terminal style and package geometry. Side-wettable flanks can improve optical inspection capability by allowing visible solder fillets, while pull-back terminals may require greater reliance on X-ray or electrical testing. At TTCI, we frequently combine AOI, AXI/X-ray inspection, Flying Probe, ICT, and Functional Test strategies to achieve meaningful structural and electrical coverage across the assembly process.

Several industry standards support proper QFN implementation and inspection. IPC-A-610 establishes acceptability criteria for electronic assemblies, IPC-7093 provides guidance for Bottom Termination Components (BTCs) such as QFNs, and IPC-7351 supports land pattern design recommendations. IPC-2221 and IPC-2222 also contribute to PCB design practices that directly influence manufacturability and test accessibility.

Understanding the anatomy of a QFN package is not simply an academic exercise, it directly impacts yield, reliability, thermal management, inspection capability, and production test coverage. A well-designed manufacturing and test strategy can dramatically reduce false failures, improve first-pass yield, and enhance long-term product reliability.

At TTCI, we believe successful electronics manufacturing begins with understanding how design, assembly, inspection, and test all work together as a complete system.

At The Test Connection, Inc. (TTCI), we provide complete production electrical test solutions to support today’s high-reliability electronics.

From In-Circuit Test (ICT) and Flying Probe, to Boundary Scan (JTAG) and Functional Test, our team ensures your assemblies are validated for performance, coverage, and quality—whether in development or full production.

We’re also expanding beyond electrical test.

With the addition of advanced inspection capabilities, including 2D X-ray, 2.5D laminography, and full 3D CT, TTCI now delivers a more comprehensive approach—combining structural insight with electrical validation. This allows us to better support failure analysis, process validation, and quality assurance for complex and high-reliability assemblies.

As an ITAR Registered and ISO 9001:2015 certified organization, TTCI is highly experienced in working within controlled environments and understands the importance of complete, accurate documentation for both electrical test and inspection. From schematics and BOMs to CAD/ODB++ and assembly drawings, we help ensure your data package supports a successful test strategy.

When reliability matters, test and inspection must work together.

Let’s connect and discuss how TTCI can support your next program.

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We just watched an impressive video from Creative Electron showcasing how advanced X-ray and CT technology is transforming battery inspection — and it’s a great reminder of why this capability matters.

Batteries are everywhere — aerospace systems, defense electronics, EV platforms, medical devices, and industrial controls. But what you can’t see inside a battery can absolutely impact safety and reliability.

With advanced 2D, 2.5D, and full 3D CT X-ray inspection, you can evaluate:

• Internal weld integrity
• Electrode stack alignment
• Voiding and delamination
• Foreign material contamination
• Potential short risks
• Post-stress structural shifts

Electrical testing tells you if it works.
X-ray shows you what’s happening inside.

At The Test Connection, Inc., we’re excited to bring this level of structural insight alongside our electrical test capabilities — giving customers deeper validation and stronger confidence in their assemblies.

Take a few minutes to watch the video from Creative Electron. It’s worth it. 🔎

If you’re building or validating battery-powered electronics, let’s talk.

The Galaxy Ring Dangerous? | VERTICAL Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

Something BIG is coming to TTCI…

We’ve been working behind the scenes on a powerful new capability that’s about to give us a whole new perspective.

Let’s just say… we’re preparing to see things others might miss. 🔍

Clearer insight.
Deeper analysis.
Nothing left hidden.

The real question is…

What does Bert Horner have up his sleeve?

You’ll find out in 10 days.

Stay tuned.

If you want to learn from one of the best in the industry, sign up and get a copy of this book from Bill.
Bill is a true leader and subject matter expert who somehow always has the answer.
This book is an absolute must-read for X-ray inspection professionals

https://www.facebook.com/share/p/1AQRajYcAm/?mibextid=wwXIfr

Thank you to everyone who downloaded The Printed Circuit Assembler’s Guide to X-ray Inspection and helped make it the most successful X-ray inspection book published by I-Connect007.

We truly appreciate the strong response and support from the electronics manufacturing community.

If you haven’t downloaded the book yet, you can access it here!
https://tinyurl.com/creativeelectron

We’re also excited to share that we’re already working on our next book, planned for release in 2026, focused on AI inspection in the manufacturing industry. This upcoming book will explore how artificial intelligence is changing inspection, defect detection, and analysis in real-world manufacturing environments.