Ability of X-rays to pass through various materials and reveal its inner defects and imperfections makes SCIOX the predetermined device for various fields, especially the one of defectoscopy. As we are the company engaged in electrical engineering and working with small electronic devices on daily basis, we decided to focus on this field in particular. Our primary concern is in the controlling processes. The interest in effective controlling process is on the increase nowadays, especially thanks to the BGA components introduction. Use of BGA or QFN is becoming more and more popular due to the growing emphasis on miniaturisation in electrical engineering. Other significant areas of X-ray use are in the controlling processes of product assemblage and in the field of security.
Soldered components check
Soldering of electronic components can be checked via optic based systems. These systems, often of a very high level, can be purchased for reasonable prices too. Nevertheless, this technology is not sufficient when talking about BGA or QFN components control.
BGA (Ball Grid Array) is a component package mount type. From the bottom side BGA is equipped with contacts in form of small balls used for the attachment to the printed circuit. See the picture below.
BGA components were invented due to the perpetual demand for miniaturizing. Unfortunately, the technical difficulties of the soldering process increased rapidly with the introduction of these packages. In most laboratories they are not able to solder the packages themselves and even the companies specialized in printed circuit board soldering have no efficient method for the verification of the precise soldering process.
The only solution for controlling the components soldering is X-ray based method. This goes hand in hand with the growing requirements for better technological equipment, especially in companies not using X-ray devices before. This growing interest in components shouldering processes makes X-ray device “a must have” these days.
Some companies rely on the probability of the correct shouldering process, solder all printed circuits and then test the device. It is the so-called trial and error method the result of which can be an unpleasant surprise regarding the expenses. First of all, most of BGA package components are quite expensive themselves. Shouldering process is time consuming and in case the circuit is not working, the wrong soldering may cause the damage not only to this particular circuit but also to other circuits on the board. Fixing the whole board is very difficult as you have to calculate with more time, more people involved, new components, repeated shouldering and last but not least the with the delay that can result in more loss.
X-ray based checking solution can help to avoid such scenario.
The most common defects of BGA components:
Missing ball – during the shouldering process some of the balls are not embedded to the package of the component well and they can fall off. Sometimes they are missing already when delivered from the manufacturer. This problem is revealed immediately by X-ray scan as the missing ball is clearly visible on the snapshot.
Bridges – during the soldering process, the balls can connect and create the short. This is a very common defect usually caused by the solder paste deposition (too much) or by incorrect board manipulation during the soldering process.
Wrong component embedding – BGA balls diameter is 0.3 – 0.7 mm on average. Therefore the risk of wrong embedding is high. Even the movement by the tenth of a millimetre can result in the wrong component soldering. Shouldering process can be checked via X-ray device to see clearly whether the balls are placed directly to pads and are of the correct round shape.
Voids/ gas bubbles in balls – If BGA components are not stored in the optimal conditions or the soldering temperature profile is not set correctly, the voids in balls can emerge. This decreases the conductivity and mechanical solidity. This is one of the most common defects during BGA soldering.
Cold joints – if the soldering temperature profile is not set correctly or there is an excess of the solder, the so-called cold joint occurs. Here, the same as for the voids applies. The device can work well during testing but the circuit damage appears after some time of using. For the cold joints it is either impossible to conduct an electrical current or they conduct it insufficiently and have a very short life-span. Also cold joints can be identified via X-ray check although this requires a little more skills from the controlling operator.
Product completeness control
In case you manufacture products by assembling electronic compartments into cases or by casting it in sealing compounds (e.g. polyurethane) there are always doubts regarding the accuracy of the assembling process or the occurrence of defects during concealment. Thanks to X-ray based control it is easy to check all components placement within the device and detect some damages of cables or other components if any.
The common production phenomenon of damaged bolts and screws can decrease the product´s life cycle considerably. Speaking of a product for home use only, this damage may not appear at all. On the contrary in applications, especially in automotive industry, such defect can cause serious problems. Automotive industry is booming now in the Czech Republic and the requirements for the efficient quality verification grow too. X-ray snapshot represents one of the few clear evidences verifying the product´s inner components quality. It proves accuracy of all components setting after the product´s assembly and testifies all parts are present and compliant with the product´s documentation.