Soldering station is a device that simplifies the process of soldering. And the direction of movement is entirely determined by the conditions. The more accurately the soldering conditions are maintained, the better the seam is obtained, but additional equipment will be required.
From the history of soldering and metallurgy
Information is known that soldering was used in Mesopotamia 5,000 years ago. Selected Sumerian swords, 3,000 years before Christ, were assembled by this method. Wrong soldering process leads to sad consequences. Scott's expedition to the South Pole died due to the fact that the tanks, brazed with tin, lost the fuel supply. A little knowledge in the field of metallurgy would be able to radically change the course of history. After all, Scott reached the pole first and was already returning back. .. Therefore, the scientific approach is important.
A welder society is registered in the USA.This is the official organization that deals with the specific issues of metal compounds. Anyone can check on aws.org. The American Society of Welders became a non-profit organization founded in 1919 to study and describe the processes of welding and brazing. The publications of the mentioned society are full of high-tech definitions.
AWS covers over 73,000 people and consists of 22 divisions dividing into 250 sections scattered around the world. Thanks to this organization, knowledge regarding welding and brazing is constantly systematized and maintained in freshness. The first difficulties the American state began to experience in the period of World War I, when the speed of creating military equipment was severely affected due to the lack of standards. President Woodrow Wilson turned to Professor Comfort Adams for help in setting up an ad hoc committee to tackle the issue.
March 28, 1919 was born AWS.In the first year of its existence, the organization grew to 217 participants, acquired its own publications and headquarters. In the early years, the society lived at the expense of fees in favor of its own magazine. Today the society is engaged in training professionals of the world, continues scientific publications, and leads the accreditation of specialists.
Soldering process: solder, flux, technological modes
Not everyone immediately understands why a soldering station is needed. For most, this is just a convenient stand. We argue that the technological regime often determines the success or failure of an event. Soldering is called the process of joining two metals using solders without melting. Flux is actively involved in the process, whose task is to remove the oxide film, improve wettability properties, and others. A number of conditions are presented for solder:
- The strength of the future joint depends on the solder.
- The alloy used in this quality is required to wet the metal being joined well.
- At the contact points, diffusion inevitably forms, the process should not reduce strength.
In detail, it is convenient to display the characteristics of the solder in the form of temperature diagrams, like those that illustrate the state of the steel. It turns out that the mixture of two metals, regardless of the percentage composition of the composition, has the same point of solidification. But the final melting occurs at different temperatures. For example, when mixing silver and copper, an alloy is formed with a ratio of 72:28 components, and the melting point( liquidus) is as close as possible to crystallization( solidus).This ensures the homogeneity of the solder at work. Otherwise, its mobile fractions at relatively low temperatures are separated.
. All this leads to heterogeneity, which complicates the soldering process. Solder, for which the liquidus and solidus differ too much, it is recommended to warm up in advance a little more than the required level. A lot of difficulties awaits a person who improperly withstands technology. List of phenomena affecting the soldering process and reducing quality:
- Hydrogen fragility is inherent in steels, copper and silver. The essence of the phenomenon is that metal oxides are reduced by hydrogen atoms that easily penetrate into the crystal lattice. The resulting water inside creates a giant pressure that destroys the metals in the weld area. It is more difficult with other things with copper, and steel can be preliminarily held at a temperature of up to 100 degrees Celsius to get rid of hydrogen.
- In steels( and other alloys) containing chromium, an active formation of metal carbide occurs during soldering. As a result, the corrosion resistance of the seam is sharply reduced. Carbide tends to be deposited in some parts of the crystal lattice. It is possible to straighten the process by heating to 1000 - 1130 degrees, which will force the joint to dissolve again, but for most solder joints this approach is unacceptable. Instead, heating is applied only to 870 degrees, followed by cooling in the oven to 540 degrees.
- During thermal loads during soldering, metal cracking is often noticed. To avoid this, annealing is often used instead of quenching. They try to make prefabricated joints without mechanical stress at the points of the seam. Heating is done gradually. The reverse side of the coin - massive details bring to condition as quickly as possible. In this case, the heat during soldering does not have time to capture the entire volume, which significantly reduces the voltage. The key is getting the right technology. Plays the role of the correct choice of solder.
- Nickel cracks when heated in the presence of sulfur. This is caused by the formation of low-melting sulphides deposited on the grain boundaries of the crystal lattice. This metal is not subject to recovery. The problem is solved by adding chromium to the alloy and thoroughly cleaning the medium from any substances with sulfur in the composition( oil, paint, lubricant, etc.).For a similar reason, soldering of iron and nickel does not use compounds with a phosphor component.
The task of the soldering station
It is important to properly handle the mode. Especially said concerns temperature. If you take BGA chips( surface array of balls), the soldering iron in this case is powerless. Instead, the substrate is preheated by the hair dryer to the desired temperature, then the chip is put in place. The technology is based on the fact that the lower contact part on top of the numerous legs contains small solder balls. They are formed from special blanks using metal patterns.
A soldering station is used to maintain the desired temperature. It is important to clean the surface after the procedure with alcohol from the flux. To further avoid corrosion. Therefore, soldering stations often contain, along with the traditional sting, a semblance of a building dryer. Moreover, the device is regulated to adjust the temperature.
Hot air is usually used, it is possible to find models for sale that work due to infrared radiation or induction phenomena( like the newest cookers).Soldering station allows full control of the process. If this is a workplace for installing SMD chips, the substrate is preheated to 150 degrees Celsius, and sometimes it is hotter. So that the components of the hybrid circuit is removed with tweezers. The temperature is specially chosen such that it acts hard on the solder, but does not cause damage to the sensitive electronic filling.
Parameters and features of soldering stations
Soldering station is designed for different purposes. For BGA microcircuits( the legs are hidden under the chip's case), the non-contact method( hair dryer) is used, and in some cases it can also be used for SMD( lateral arrangement of the legs).It is necessary to clearly understand what happens in the end, because consumables are used different. For small integrated microcircuits, it is not bad to have special grips( more commonly called vacuum tweezers or suckers), and the alignment in a small range is done with ordinary steel tweezers.
Sometimes the specified equipment comes with the soldering station kit, it is easy to keep an eye on in the store, for example, at Aliexpress. If we are talking about contactless soldering, it seems reasonable to find equipment for sale with a special dome for preheating the board. You can watch a video on YouTube, where an inexperienced master fails in the process of dismantling the SMD chip for the simple reason that the surface of the crystal is large and the legs are located for a long distance. It is required to heat the entire structure to a temperature of 210 - 350 degrees( depending on the brand of solder).Immediately posted video, where another pro removes the board stuffing with ordinary tweezers, preheating everything on the dome. Draw your own conclusions.
Indirectly, the maximum air temperature( or tip) depends on the power consumption. On sale there are soldering stations, basking to 425 degrees Celsius. This is enough to work with low-melting solders( up to 450 degrees Celsius).If you need to apply a copper-zinc alloy, in such conditions will not work. But it will be possible to easily handle tin-lead or silver solders. If you look at the construction market, it is easy to find a hairdryer with a jet temperature of 800 or even 900 degrees Celsius. This makes it easy to melt the copper-zinc solder, but the control over the heating process will not be as accurate.
operation In certain conditions, this is not very important, and sometimes - on the contrary - is critical. Increasing the mass fraction of zinc reduces the melting point, and brittleness increases. Heating control is carried out through potentiometric regulators( rotary knobs).There is a small display on a good soldering station, where the temperature is shown in numbers. It is convenient, it is possible to adjust the mode with an accuracy of fractions of percent only in this case. The maximum temperature depends indirectly on the power; this also affects the speed of the exit to the mode. Soldering station can not be called the main consumer. Rarely the power of the device exceeds 100 W( equivalent to the system unit of a personal computer).
When using the contact method, take the trouble to purchase a sponge for cleaning the soldering tip. It is a non-flammable rag of polymeric origin that helps keep the tool clean. The sting in severe cases is cleaned with a file or a file, and flux is also used, removing the oxide film and solder residues. The surface is practically mirror-like for soldering microelectronics. On YouTube, it will be advised to have high flexibility of the copper braid board used as an abrasive for hot stripping of the contact pads.
Without elementary equipment, the reballing operation will fail. Common devices include:
- Flux for cleaning contact surfaces.
- Metal masks according to the shape of the contact pads of the microcircuit.
- A set of balls of solder on the size of the holes of the template.
Professional masters sometimes do without a magnifying glass, but for a beginner to solder a chip with a side of 2 mm is difficult in the absence of special devices.