Introduction
When it comes to electronics, these days most people lean towards gadgets whose function is easily understandable: a washing machine or an electric chainsaw, to give two random examples. But how do you explain to someone everything that is needed to make their equipment work? In reality, it is deeper than many imagine.
In this sense, we will talk about the PCB. If you were able to disassemble an electronic device at some point in your life, you surely have found yourself with a “green card”. This, in simple words, is a PCB. It is mostly a PCB X-ray machine.
X-ray inspection in the electronics industry is a non-destructive procedure that has gained important relevance in manufacturing and assembling printed circuits to detect faults inside and below their components and their structures, which otherwise could not be observed. An example of this is the need to detect defects in the internal layers of a multilayer printed circuit or to be able to inspect the welds located under components that do not have pins, procedures that make it essential to be able to see through them to locate what we are looking for.
The importance of PCB in modern industry
Motherboards have become the engine of most technology, being placed inside our everyday objects.
In the era of technology in which we find ourselves, printed circuits are essential to carry out many of the tasks that we carry out every day. If we focus on our homes, we have a large number of devices that allow us to do tasks more comfortably and easily.
Technological evolution is allowing devices in the home automation sector to be increasingly small. One of the reasons is that the PCBs are allowing it, in this way we reduce their size to optimize the space of the device to the maximum.
One of the biggest challenges that companies have is finding a partner for the manufacture and assembly of printed circuits. It is important for the client and helps to choose the quality of the board and / or components according to the life cycle of the product. that you want to achieve.
The future is technology and the growth in new knowledge will allow us to be a protagonist in the digital evolution that both companies and consumers are experiencing. The investigation of new materials for the application of the printed circuit in different products is helping to improve the results in terms of product efficiency and effectiveness.
Principles of X-ray Inspection
The principle of X-rays is that non-destructive inspection can be performed by emitting high-frequency electromagnetic radiation formed by photons.
The dense elements absorb more photons and appear black, the less dense elements are crossed by the photons and can be seen more easily through them.
These properties allow for a very detailed inspection of multilayer PCBs in 2D and 3D. On some machines, a joystick is used to scan the printed circuit board with ease in a flight simulator and check solder joints and components on all sides layer by layer.
Through X-ray inspection, non-visible defects and failures are detected in the process, such as errors in the soldering of electronic components or detection of defects in internal layers of circuits or under the same components that are not detectable with a visual inspection.
Many highly sensitive industrial X-ray equipment, both conventional and digital, carry out this inspection. With conventional equipment, the results are obtained on radiographic plates in plastic support. With digital equipment, an image is obtained in an electronic format that can be processed using software to improve the quality of the inspection.
How to use x-ray to inspect PCB?
Pcb x ray inspection state-of-the-art technology is a very useful tool in the following printed circuit manufacturing processes:
Drilling multilayer circuits:
The multilayer circuit drilling process is implemented once its internal layers have finished their lamination process, ending with their TOP and BOTTOM faces covered with a 17- or 35-micron thick copper layer and that must be processed from now on as a conventional circuit, with the difference that the perforations made must coincide with the pads of the internal layers already pressed. This precision is easily obtained by taking an X-ray image through the outer layers of raw copper to locate the reference fiducials located in the card’s inner layers and punch or calculate the deviation inherent to the lamination process to make match your pads with the center of your perforations.
Analysis of the metallizing layer of the PCB:
These procedures allow, through the use of algorithms, to accurately evaluate the characteristics of the metallizing process inside the tracks on the printed circuits. In the left image of the following graph, the duly metallized walls of a road in an 8-layer circuit are evidenced, determined by its darker appearance on its sides due to the greater absorption of X-rays, as it is irradiated obliquely.
Conclusion
The use of this technology in the assembly processes is very valuable since it allows us to precisely adjust the temperature profile of the soldering processes on boards that contain components without pins, by being able to observe the microstructure of their solders. Its implementation in the quality controls of a manufacturer will undoubtedly improve the robustness and reliability of the products, also obtaining the most important thing: Customer satisfaction. A PCB board is a reliable and durable board. If you intend to use your PCB for more than a few years, keep regular inspection from time to time and keep it well protected from contaminants.
