The electronic devices manufactured today use various assembly technologies. This is not particularly important for users during normal operation, but in the event of failure it becomes crucial, as the requirements for diagnostic and repair methods and tools depend on the technology.
Sometimes the working systems are disassembled in order to replace them with slightly different ones, and by measuring the results of such changes – this is the case e.g. when testing prototypes. One of the basic conditions for effective and safe work is the use of appropriate tools. In many cases these must be specialist instruments, which cannot be replaced by simple means. Dismantling electronic components also requires the use of methods and tools that take into account the characteristics of specific components and systems, such as dimensions, shape, type and number of leads, method of assembly, sensitivity to temperature, mechanical resistance, and sensitivity to electrostatic influence.
Sometimes the operating systems are disassembled in order to replace them with slightly different ones, and by measuring the results of such changes – this is the case, for example, when testing prototypes. One of the basic conditions for effective and safe work is the use of appropriate tools. In many cases these must be specialist instruments, which cannot be replaced by simple means. Dismantling electronic components also requires the use of methods and tools that take into account the characteristics of specific components and systems, such as dimensions, shape, type and number of leads, method of assembly, sensitivity to temperature, mechanical resistance, and sensitivity to electrostatic influence.
In the electronic equipment in use today, there are very different types of assembly: traditional point-to-point spatial assembly, characteristic of tube equipment, still used today by some manufacturers of acoustic amplifiers built with this technology; spatial assembly on ceramic strips, used, for example, in some measuring instruments; assembly of THT type elements on single-sided, double-sided plates, up to multilayer ones with metallization of holes; surface assembly of elements of different construction.
During disassembly, it is necessary to melt the solder, pick the disassembled element, lift it and move it outside the board.
The solder must be removed from the soldering points, then the places must be thoroughly cleaned and prepared for installation of the new element. Sometimes it is necessary to repair the surface, e.g. regeneration of paths and soldering points. The best known disassembly method is to work with a soldering iron and a spring suction unit. The inconveniences and limitations associated with it are also well known. It is known that efficient disassembly of the element saves time, energy and reduces the risk of damage, e.g. caused by overheating.
Achieving efficiency requires specific technical solutions that take into account, among other things, the number of disassembly operations, the variety of components to be disassembled, the types and scope of other operations carried out on the same site, the time standards set, or specific conditions, such as those relating to servicing the equipment at the site of installation and operation.
PACE DEVICES FOR DISMANTLING ELECTRONIC CIRCUITS
To illustrate the existing possibilities in this area, it is worth to return to the offer of PACE, presented in the article titled „The possibilities of the PACE company”. „What do they solder with at NASA?” (ReAV No 9/2002) in the context of applications for assembling electronic circuits. Already soldering handles PS 70/PS 90, cooperating with ST 25 to ST 55, can be equipped with disassembly tips, but only specialist handles with dedicated tips and heads ensure proper work efficiency. PACE offers five disassembly handles (one of them also enables assembly), designed for cooperation with stations – from single-channel ST 75/ST 115, through two-channel MBT 201, three-channel MBT 250/MBT 220 to multichannel PRC 2000.
Suction handle SX-80, designed to dismantle all types of THT systems and TSOP and TQFP systems. Dismantling of the THT elements is carried out with the use of an appropriately selected suction nozzle. After setting the desired working parameters of the station and warming up the nozzle, it is applied to the soldering point so that the tip of the lead of the disassembled element is located in the nozzle opening. As the solder melts, the nozzle must be pressed gently against the surface. When the compressor is turned on at the right time, the solder will be extracted from the surface of the board and from the hole – the tip of the element is released.
Precision TSOP and TQFP disassemblies use heads with dimensions corresponding to the housing of the specific system. In this case, the station compressor is not used for tin suction, but feeds a suction cup, placed between the working edges of the head, to lift the soldered element.
The handle of the TT-65 thermocouple for dismantling SMD systems: CHIP, SOIC, PLCC, connectors. The principle of operation and possibilities resulting from the variety of tips to be used is illustrated in Figure 2.
TP-65 Thermopik handle for disassembling PQFP systems, working with 11 standard heads. The head heats up all the element’s leads simultaneously. Before disassembly, the edges of the head are covered with tin to ensure efficient and even heat transfer. Then, with some movement, the head applies to the system leads, pressing lightly as the solder melts.
Because the TP-65 handle is equipped with a suction cup, it allows you to pick up and move the desoldered part.
