Every electronics engineer is aware of the widespread use of SMD components, especially BGA, which are used in mass production of electronic devices. The complexity of products such as mobile phones or laptops makes it necessary to struggle with increasingly complex elements and smaller printed circuit boards.
These problems are known to all electronic engineers, but solving them causes a number of problems that have been difficult to solve so far. Especially working with BGA components, being more difficult than with other SMD components, creates many complications. A large number of soldering points located under the housing of the system, makes it practically impossible to carry out assembly/disassembly by hand.
To avoid short circuits or gaps, the BGA system must be perfectly positioned before soldering, it is also necessary to use soldering technology as close as possible to the production conditions prevailing in reflow furnaces (multi-zone process – preheating, proper heating, cooling.
The most common way of assembling and disassembling BGA is by blowing hot air stream. This method is widely used in both manufacturing and repair companies. Many service companies take up the fight against BGA using tools such as heat guns or simple hot air blowing stations. Uniform heating of 200 or even 700 BGA soldering balls requires great precision in process control, so the fight is usually lost and the „war“ is likely to be costly to the budget.
Devices capable of performing such complex tasks as BGA repair have so far cost between 50000 and 450000 PLN and were only available to the chosen ones. The equipment offering high quality optical capabilities, enabling extremely precise positioning of even very small components, additionally supported by X-ray inspection equipment, is and certainly will remain beyond the financial capabilities of most service companies.
It is worth noting, however, that these costs are justified by the extensive profile programming options, a high-resolution positioning system based on an optical system and software (positioning systems on the computer screen) and cooperation with X-rays, etc. In this range of available products, PACE TF-1500 (price about PLN 100000) is the most effective.
Nowadays, thanks to the latest, technological and at the same time economical hardware solutions from PACE, effective and safe work with SMD elements, including most of the BGA, is already possible to be conducted even by small service shops. Skillful use of these products will ensure effective performance of tasks, which until recently were the domain of only companies with very expensive service equipment.
Currently, the purchase of devices enabling work with BGA is an expense from 7000 to 12000 PLN. One of the most universal devices on the market, perfectly fulfilling the role of a basic tool in any workshop undertaking struggle with boards with a high degree of integration, is the ST-325 PACE hot-air station.
DISMANTLING SMD/BGA – IT’S EASY!
Already standard equipment of the station will make it possible to work with most SMD elements. In the case of more complex applications, it is advisable to select a head for a particular type of element – the manufacturer provides a wide selection of them. Accurate selection of the head to match the component is extremely important, as it is an important factor for the uniform temperature distribution over the entire surface of the component to be removed and protection for surrounding components.
Disassembling the elements with this station is extremely simple – first determine the level of temperature and the amount of supplied air, then from a distance of about 3 cm direct a stream of hot air onto the element to be disassembled cousing melting of the solder on the outlets. Now it is up to you to lift the element – you can use the vacuum gripper built into the station handle or an independently operating vacuum tweezer from the standard station equipment.
Often, after dismantling the system, it is necessary to reinstall it e.g. for diagnostic work. In this case, it is easy to „recreate“ the missing balls – soldering points and install the system according to the saved profile using a properly selected set for component regeneration (template, screen, balls). The whole process is precisely supervised – the device is equipped with controlling microprocessor and a clear display, the temperature of the air stream is stabilised at ±9°C, with a maximum setting of 482°C, temperature control makes it easy to use the thermocouple.
BGA ASSEMBLY – INCREASING DIFFICULTY
The installation of BGA systems is a much more difficult task, as it means that you have to use advanced tools that offer precise positioning and process guidance according to programmed profiles. It is required to maintain in each zone the set time, temperature and amount of supplied air – a failure to maintain the profile even in one zone usually results in a complete failure. Soon to happen, the transition to lead-free alloy soldering technology will make this regime even more difficult.
And it is in such complex tasks that you can see the true value of the ST-325 – versatile expandability, enabling you to create an efficient and cost-effective tool for working with SMD elements (including BGA). Equipping the station with a tripod for stable board mounting and positioning, as well as a heater and process management software, will create an advanced station to meet most of the needs that may arise in service technicians’ work. An important function in this kit is the heater connected to the station, which ensures even temperature distribution over the entire board and pre-positioning of the board and components.
Dedicated to work with ST-325 station is PACE ST-450 heater. This tool heats the plate with a stream of hot air directed through profiled heads. ST-450 as an integral part of the workstation is controlled by the software from the PC, but it can work independently of other elements of the set (similarly to ST-400 heating PCBs with infrared heaters). Obtaining the correct soldering profile, usually set by the manufacturer of the BGA system is necessary for its proper installation or disassembly. Not maintaining the set parameters will end the work with short circuits, breaks or overheating of the element. Four-zone soldering profiles can now be very easily programmed and saved in the memory of the computer or station, and the process can be observed on a computer chart drawn in real time. Graphical interface of the application proper for Windows environment, intuitive operation and possibility of archiving are other advantages of the workstation based on ST-325.
Until now they were only available in much more expensive equipment. As you can see, SMD/BGA components are perhaps not the easiest thing to do, however, with the right equipment, even with little operator skill, safe and quick to do. In the PACE ST-3xx series, apart from ST-325 presented above, the manufacturer also offers two other hot air blowing stations: ST-300 and ST-350. PACE ST-300 is a slightly simpler analogue equivalent of ST-325, which is not equipped with the possibility of cooperation with a PC.
However, it has most of the advantages of the ST-325 and seems a good solution for working with typical SMD components – either manually or with a tripod and heater. The user must remember, however, that the possibility of expanding this device is in practice limited mainly to equipping it with heads for specific types of components.
The ST-350 is a version of the ST-325 combined with a special tripod in a compact set that allows positioning of systems on boards with a maximum size of 457×457 mm. The ST-350 design ensures very precise positioning of components, this is guaranteed by micrometric screws and adjustment of system position in X, Y, Z and Theta axes. Further easy extension of the station with e.g. a dispenser is also possible.
This model should be considered suitable for companies whose needs go beyond the possibilities offered by the ST-325 – it is even possible to work with NBGA/CSP Fine Pitch“ components, which places this station in a very narrow circle of the most versatile tools on the market. Looking at the offer of the hot air blowing station, one cannot overlook a very interesting Polish construction REECO RA-250e, whose advantages setting it at the forefront of the stakes are: microprocessor control, profile programming (unfortunately without the use of software), built-in vacuum tweezers and a thermometer with an external thermocouple.
This station can also be extended to a station whose efficiency goes beyond manual positioning of elements (tripod, heater, etc.). REECO RA-250 will not compete with PACE ST-325 station, but many potential users will pay attention to its most important advantage – attractive price with really extensive capabilities. Of course, even the best equipment is not able to perform even the simplest tasks by itself. The most important element in every company is a man and it is his skills that determine the quality of the work.
The implementation of new technologies should therefore start first and foremost with improving the skills of those who have new equipment to operate. As far as work with BGA is concerned, one of the training courses conducted by RENEX EEC can be mentioned. Particularly noteworthy is the course RTC-08, dedicated to: Acquiring theoretical and practical knowledge in the field of assembly and disassembly of BGA/CSP components, and getting acquainted with the methods of reconditioning leads and quality control of component connections“. Although the reliability of modern products is high, their universality is causing more and more orders for services. Running a service company has to be economically justified, so quick and effective repairs are a measure of efficiency. The new generation of very versatile and cost-effective equipment is the answer to the question: „How to install and dismantle SMD/BGA professionally in small repair companies“.