Lamps have been used for a long time as the main working element of lighting systems. They have gone through many stages of structural and functional development, but today they are experiencing a crisis due to fierce competition with diode crystals. Modern LED lamps are widely used due to their performance, which, however, have negative aspects of application. In the process of repairing such a device, the user may encounter the problem of updating failed crystals. The question of how to solder an LED logically arises if one of the crystals is burned out. This will be indicated by the presence of a black dot on the yellow surface of the element. And if, under the conditions of the factory layout, the restoration operation is performed mechanized in a streaming mode, then in everyday life it will be necessary to organize the conditions for manual soldering.
What are the types of LEDs?
In most casesordinary users of lighting devices are dealing with output LEDs and a more advanced design based on SMD crystals. The former are introduced into the circuit using two conductors and most often serve as a means of indicating various equipment - for example, in a car they perform the tasks of a light signaling device, operating from a 12 V source. SMD diodes in leadless cases are more often used directly in lighting and backlight systems. In view of the fundamentally different electrical layout on the board, it is this lighting device that will most likely cause difficulties. How to solder SMD LEDs? Fastening is carried out not through special holes, as is the case with the same output devices, but directly on the surface with a patch. For this, special contact pads are provided, which must be soldered one by one, maintaining the correct placement of the diodes on the board. On the one hand, this approach simplifies the technology of mounting crystals, but on the other hand, it requires more attention from the performer, since you have to deal with elements of miniature size, compactly placed in a small space.
Preparation for work
As part of the preparatory process, several tasks must be solved. The main one is cleaning the working surface and, if necessary, dismantling the burnt diode. Old parts are best removed with low-power 25W soldering irons after the tip has been tinned to the required size, which will allow you to conveniently make a thermal cut. Further specialattention is paid to the surface. Varnishes and all kinds of technical coatings must also be removed mechanically - for example, cleaned with a construction knife. Now another question - how to solder LEDs to aluminum boards? In this case, it will not be superfluous to prepare a special flux for a particular metal or use a universal tin-lead solder. As for the choice of soldering iron, there will be no need for high power. You can give preference to compact models with heating up to 250 ° C.
Angled connection technique
Often, when creating complex lighting systems from several parallel lines, wires are connected in different areas. For the convenience of making such a connection, angle soldering with a 90-degree inclination is used. Plus and minus are fixed on the contact pads of two neighboring diodes. More importantly, this method makes it easy to connect RGB strips using four wires. The corner joint does not affect the quality of the backlight in any way, but allows you to implement a variety of configurations for splicing LED strips. Only the presence of a special sheath for tapes with a protection class higher than IP68 can cause problems. For example, how to solder LEDs filled with silicone or compound? In this case, the initial cleaning procedure becomes more complicated. At a minimum, it will be necessary to form technical holes in the coating for current-carrying conductors. Soldering is carried out on them in the future.
Connection technique using connectors
Among the advantages of LED devicesone of the main places is occupied by their optimization, which is also manifested in the minimum requirements for consumables during installation. Nevertheless, sometimes the inclusion of connectors in electrical circuits justifies itself. How to solder LEDs with such elements? Soldering in this case acts as an auxiliary means of ensuring a reliable connection between the wires, and the connectors form a kind of reinforcing inner frame. The optimal size of the connector in width is 8-10 mm. At the first stage, it is necessary to create a structural connection by making the required number of contacts on the board, and then proceed directly to soldering.
In this case, it should be borne in mind that the connection with the connector does not always give an advantage in terms of the future operation of the LED. Firstly, the connection points with such fittings are more prone to burning, and also contribute to the rapid heating of the emitter. Secondly, the glow may worsen, which is expressed in a decrease in brightness. How to solder LEDs on a board with a connector to eliminate such negative effects? It is advisable to abandon the copper conductors, and perform the soldering itself in a continuous way, which will eliminate the risk of formation of oxidation sites.
Splice technique
A method that does not involve the use of auxiliary conductors at all. This technique is recommended for strip lamps and other diode devices, the crystals of which are placed compactly on a small board. For example, how to solderSMD LED soldering iron overlap? To begin with, the ends of the LED lines are cut so that the contacts are close to each other. The current-carrying cores are lubricated with flux, after which tin tinning can also be applied until a silvery coating is formed. Then one piece with a wired part is overlaid on another segment with strict observance of polarity. A short gentle warm-up is enough to form a strong bond.
Soldering order
Whatever connection method is chosen, the general soldering technology involves a universal set of actions, including the following:
- Solder or flux is used to tin the current-carrying contacts that are planned to be connected.
- The ends of current-carrying cores that have already been tinned are applied to the junction on the board or another conductor.
- Now the main operation is the connection. How to solder LEDs manually? It is enough to point the soldering iron tip at the target area of \u200b\u200bthe connection and hold it for 3 to 5 seconds. As a result of rapid heating, a reliable joint is formed.
- After soldering, it is desirable to keep the docking station in an isolated form for several hours without any external influences.
Features of soldering with a hairdryer
Soldering in this way is generally regarded as an alternative method to conventional soldering. It is chosen for various reasons, the main of which can be calledthe possibility of heat removal from the crystal with minimization of the risks of its thermal damage. But this method is only suitable for designs with a surface connection on the board. For example, how to solder SMD LEDs with a hair dryer? The heating process is organized on the reverse side of the board. The task of the performer is to ensure sufficient heating of the connection area so that the solder on the front side acquires a state that allows you to securely fix the diode. Theoretically, this action can be implemented with an iron and a low-power gas burner, but it is still safer to use a special hot air gun to preserve the structure and the board itself.
Soldering errors
Even if the externally created connection seems to be correct, the device may not work correctly if technological errors were made. Most failures are due to improper distribution of the solder or melt, which results in typical defects such as lack of fusion. How to solder LEDs to avoid this result? Both the solder and the melt must be strictly controlled already in the course of thermal exposure. The uniformity of the layers of the connecting coating must be maintained. To detect such violations in the structure at the stage of non-destructive testing, a thermal imager is scanned.
Conclusion
Soldering LED-lamp crystals is an easy operation that any home master can do. However, there are many technological subtleties and details, ignoring which can nullify even the efforts of a diligent master. It is necessary to take into account not only the conditions for performing soldering as such, but also the configuration of the connection itself. For example, how to solder SMD LEDs with a group arrangement of crystals? To successfully complete such an operation, even at a basic level, it will be necessary to determine the electrical circuit for mounting diodes on the board. It is necessary to calculate the circuit and only after that proceed to the element-by-element connection of the crystals in accordance with the planned configuration of the lighting device.
