Electronics quality control using X-ray in Comarch IoT Plant

Quality control is a key aspect of electronics manufacturing. However, due to the increasing complexity combined with miniaturization of electronic components, the challenge is to detect defects that can affect the performance of products. This forces the development of more and more accurate inspection methods and accompanying technologies to support the analysis of results. Non-destructive testing (NDT) is helpful, which allows you to conduct an inspection using X-ray radiation (X-ray) and computed tomography (CT) in a precise way. Both methods are successfully used in Comarch IoT Plant.

How does X-ray Control Work?

The X-ray inspection equipment consists of three basic parts:

1. X-ray tube – an artificial source of X-ray radiation
2. Operating platform – moving the sample in different directions (x,y,z), which allows it to be controlled from different angles and in different approximations.
3. Detector – located on the other side of a sample that captures and collects X-rays, transforming them into an image. 

The X-ray scanning technology is based on the phenomenon of X-ray penetration through the object being examined. The detector located on the opposite side of the test sample records changes in the intensity of radiation, which allows to obtain an image of the internal structure of the test object. Thanks to the high image resolution and the ability to change the contrast of examined objects in real time, it is possible to quickly analyse and manipulate the results.

What is important in this context, there are different classifications of X-ray machines. The division of X-ray cameras most often refers to the way images are produced. On this basis, we can distinguish:

• 2D system, which characterize the generation of images representing the internal structure of the examined object in only two dimensions. They give the possibility of imaging results in real time, and images are most often stored in digital form.
• 3D system that uses computed tomography (CT) to image the three-dimensional structure of the examined elements. It allows you to obtain highly detailed images of the internal structure of integrated circuits, printed circuit boards, electronic modules and other components, and then visualize the results in the form of slices (individual layers) or generated 3D image. At Comarch in IoT plant we use this type of X-RAY machine – GE MICROMEX 180 equipped with modules: Planar CT, BGA Inspection, Multilayer Measurement, and Voiding Calculation.

Can X-ray inspection be automatic? 

Automated X-ray Inspection (AXI) is a technique for automatically examining soldered connections and other components on printed circuit boards using X-rays. In addition to AOI (automatic optical control), ICT/FCT functional tests and environmental tests, it is one of the most important stages of quality control that we carry out at Comarch IoT Plant. 

AXI is ideal for fast and accurate detection of defects in a big number of samples. In addition, AXI allows for precise comparison of samples between different strength or thermal tests. Automation optimizes operation by reducing inspection time for serial production and multi-level test scenario. 

This method can be implemented using:

• CAD input for building extensive control programs.
• lists of control points to be determined from the scanned sample.
• macros, which are an extended version of the control point list with enhanced inspection features;
• Voiding Calculation – automated measurement of air bubbles with the help of a dedicated module.

The role of X-ray control in SMT/THT process validation using Voiding Calculation

In this context, the last point deserves particular attention and broader development. Voiding Calculation (calculating gaps in the solder that resemble blisters) is the process of analysing the image of solder joints applied during SMT surface assembly or through THT assembly. The result of such analysis is the assessment of the presence of air spaces, the permissible amount of which is determined by the IPC-a-610 standard for the production of electronics. In revision G, the standard specifies a maximum of 30% or less gaps in any sphere in the X-ray image area. There are exceptions where manufacturers may use tests or analyses to develop alternative criteria that take into account the end-user environment.

The Voiding Calculation process usually starts with taking photos of solder joints using the AXI method. Then, with the help of specialized software, the image is carefully analysed and the areas where there are voids or air spaces are appropriately highlighted. To precisely determine the size and number of cavities, the software uses information about the shape and size of the solder joint, and also determines their percentage of the total soldering surface. The results are presented in graphic form, which facilitates their later interpretation.

During SMT and THT process validation, X-ray scanning enables two key steps: A thorough analysis of the quality of solder joints and setting the optimal solder profile parameters for surface or through-soldering using a soldering wave. Operators of soldering machines can see exactly how the solder joints behave during the process, as well as detect any irregularities in their structures. As a result, they are able to optimize soldering parameters such as temperature, time and speed, which allows for the best quality of connections and optimization of the SMT and THT process, while minimizing the risk of defects.

Checklist for Common integrated circuits (IC)

X-ray inspection for BGA, QFP, SMD and other integrated circuits shall be subject to:

1. Enclosure: The enclosure is detached from the rest of the chip, cracked or damaged on the surface of the enclosure, voids and air bubbles, breaks in microwire bonding.
2. Printed circuit boards: Track displacements and discontinuities, grommets damage, laminate and copper delamination,
3. Soldering of elements: No dampening, incorrect amount of paste, blisters.
4. Continuity: Open circuit, short circuit, faulty or erroneous connection.
5. BGA balls: Cracks, cold solder, short circuits, inclusions, deficiencies.

The most common defects that we detect with the help of X-ray

Quality control at Comarch IoT Plant – business benefits of X-ray scanning 

In Comarch IoT Plant, a modern production hall located in Krakow, we manufacture electronic devices, provide services of prototyping, assembly of electronic components (EMS), as well as their quality control. An element of the last service is automatic X-ray inspection – as we showed above, one of the most effective methods of checking electronic components.

- X-ray scanning is a valuable quality control technique in the electronic manufacturing industry. At IoT Plant, we use them to check electronic components for defects, as well as measure various parameters of various elements. In addition, we use X-ray to validate the SMT process and prepare the soldering profile for the refilling process, resulting in high-quality products that meet customer expectations – says Tomasz Jaje, Technical Manager at Comarch IoT Plant.

We carry out quality control using X-ray both for the development of our own products at Comarch and as part of professional support for external customers and their solutions. An independent investment in X-ray inspection technology within your own production line is a financially demanding undertaking, so using the services of an experienced partner allows you to optimize the costs of quality control, and in a broader perspective of the entire production. 

Thanks to many years of experience gathered as part of R&D activity and electronics production at Comarch IoT Plant, we offer services at the highest level, in line with current standards and trends. If you want to know more, please visit our website or contact us directly.