Surface-mount technology equipment
What Are Different SMD and BGA Rework Stations?
With each coming year, the amount of various electronics used in our day-to-day life increases. Obviously, all these electronic devices need constant maintenance and occasional repair. Perhaps the most difficult type of repair that is often encountered in electronics has something to do with PCBs - Printed Circuit Boards. Surface mount technology (SMT) method is widely used in producing modern circuit boards which are then called SMDs (surface-mount devices).
SMD development began in the second part of the 20th century and since then these devices were constantly gaining popularity. In contrast to the through-hole method, which uses wire leads to place and connect components into small holes on the circuit board, SMT method predicts placing the components directly on the board. SMT has many advantages over the through-hole method, such as, smaller size, high component density and lower cost, but some disadvantages as well, one of them being more a difficult repair process. A special rework station is used for repairing these devices.
The two main parts of a typical SMD rework station are the heating element and the main block. Two different types of heating elements exist: hot gas and infrared. Both have some advantages and disadvantages over the other.
Infrared method uses infrared electromagnetic radiation to melt the solder and place/remove electrical components from the board. Hot gas method uses hot air or inert gas (such as nitrogen) to heat up the solder. Infrared SMD rework stations have a very easy setup and are quite simple to operate. They have no need for compressed air and, therefore, do not require different types of nozzles. They do, however, heat up the central areas more, have a less precise temperature control and may have different factors (such as surface shape) affect the surface temperature. Hot gas SMD rework stations, on the other hand, heat up the working area evenly and have a quite precise temperature control. They are a bit more difficult to operate as they require using nozzles of various sizes and shapes for different situations. Hot air SMD rework stations are a bit more common than infrared. However, a hybrid technology that combines both the hot air and the infrared method is also becoming quite popular.
One of the more popular types of surface-mount method is the ball grid array (BGA), which uses balls of solder placed in a grid pattern to conduct electrical signals between the PCB and the integrated circuit. BGA method has many advantages. It offers a high density of pins which is very useful for producing small packages for integrated circuits. BGA packages also have high heat conduction which prevents chip overheating, and low inductance that prevents occurring of signal distortions. Despite all of the advantages, there are quite a few disadvantages as well. Solder joints may fracture if affected by vibration, mechanical or thermal stress. These packages are also very difficult to inspect once they have been soldered into the PCB. Additional equipment, such as special microscopes or X-ray machines, is necessary to find faulty solder joints. This equipment is quite expensive, as well as the equipment necessary for soldering the BGA packages.
BGA rework stations are used for repairing and maintaining ball grid array packages. There are also two types of BGA rework stations: hot air and infrared. The two are quite simple in both the functionality and the list of advantages/disadvantages to their SMD counterparts. Hot air method was the first to be invented and, therefore, it is not surprising that for quite some time it was both more popular and common. The infrared method was invented later and although there is still a lot of effort that is being put into its development and improvement, it is quickly gaining popularity and is also becoming quite common.