At the time of this writing, the CoVID-19 pandemic has resulted in a worldwide shortage of protective masks. As part of the fight against the SARS-CoV-2 coronavirus, some companies are changing their usual production and starting to produce personal protective equipment (PPE). Thus, in March of this year in China, Foxconn was in first place in the production of protective masks. As the coronavirus now rages in Europe, Russia, the United States and many other countries around the world, the world's largest companies are following in Foxconn's footsteps, but not all are surviving. Thus, the Italian company Miroglio, specializing in the production of ready-made clothing and fabrics, recently announced the cessation of production of masks. But the German company Weber Ultrasonics, which develops components for ultrasonic welding, does not produce masks, but their technology is crucial for PPE manufacturers around the world. It is for this reason that close attention is paid to ultrasonic welding technology today. From this article you will learn what this technology is and how it works.
Today it is quite difficult to find industries that do not use ultrasonic welding.
Method of soldering parts with an ultrasonic soldering iron
The method can be used to restore parts by soldering using ultrasound.
The solder is fed in the form of a rod through a hole inside the copper solder rod. The solder is melted by heating the soldering rod with an electric heating coil. The upper part of the end of the soldering rod is made of a spherical shape to smooth the resulting layer of solder. The method allows you to expand technological capabilities while improving the quality of surface treatment of parts. 1 ill. The invention relates to the restoration of parts by soldering, namely in our case, soldering using an ultrasonic soldering iron.
There are many known methods of restoration and manufacturing of parts by soldering, in which ultrasonic soldering irons are used. According to a literary source, a method of soldering with an ultrasonic soldering iron UP-21 is known, which operates at a frequency of 20-26 kHz from an ultrasonic generator. The disadvantages of this method are as follows: solder is supplied to the seam being processed (surface), individually applied to the seam being processed (surface) in the form of a rod, which significantly complicates the soldering work as the time to complete the work increases and the quality of the work performed (soldering) deteriorates.
The closest analogue of the claimed invention is a method for soldering parts with an ultrasonic soldering iron (SU 831447, IPC 7 B 23 K 1/06, 05/30/1961), according to which solder is fed through a hole inside the soldering rod, and it is melted using an electric heating coil.
The objective of the invention is to expand the technological capabilities of soldering seams (surfaces) while reducing the time required to carry out work and improving the quality of processing, as well as providing more convenient work for the performer.
The specified technical result is ensured by the fact that solder in the form of a rod is inserted into the body of the soldering iron (into the ultrasonic vibrator), which, when heated by the electric heating coil, melts and enters the seam (surface) being processed, compacting and interspersing solder elements into the seam (surface) with the help of ultrasonic vibrations , which destroy the oxide film on the surface being processed, and the upper part of the end of the rod, made in a spherical shape, smoothes and incorporates (under its pressure) the applied layer of solder, which ensures the completion of the given task.
The drawing shows a diagram of a device (ultrasonic soldering iron) that ensures the implementation of the proposed method.
The method is carried out as follows. On a machine, on a special installation or on an automatic line for soldering parts, or manually, parts for soldering are installed, previously prepared for soldering according to the technology. Soldering with an ultrasonic soldering iron is carried out using low-temperature solder, which has some features when soldering aluminum parts, which are explained by the formation of a strong and refractory oxide film on the surface of the parts, which prevents the parts from joining. When soldering with this soldering iron, ultrasonic vibrations occur in the molten solder, which destroy the oxide film on the parts. The surfaces of the parts, free of oxides, are well connected to the solder and provide strong soldering.
Example. The parts are soldered using an ultrasonic soldering iron shown in the drawing. Soldering with low-temperature solders is carried out with preliminary preparation of parts for soldering, soldering and processing of parts after soldering. Preparing parts for soldering includes cleaning the edges of parts from contamination and oxides, heating the parts to soldering temperature, fluxing (if necessary) and tinning the surfaces to be joined. Next, the product is assembled, ensuring a gap between them of 0.05-0.20 mm. Then the tip 8 of the ultrasonic vibrator 3, the soldering iron (copper rod 6) is brought to the junction of the parts to be connected 1, where the ultrasonic vibrator 3, operating at a frequency of 20-26 kHz, using the spiral 4 of the ultrasonic generator, supplies ultrasonic vibrations to the molten solder, which, destroying the oxide film on the parts, are connected to solder 2, which is fed in the form of a rod 7 into the hole of the vibrator (which is made along its axis), melted by heating the copper rod 6 using an electric heating coil 5, smoothing the applied layer of solder using a tip 8, ending the process rations.
Low-temperature soldering has become widespread in car repairs, namely in the repair of water and oil radiators, electrical parts of fuel tanks and other parts. The quality of soldering is usually controlled by crimping parts with compressed air or water.
A method for soldering parts with an ultrasonic soldering iron, including supplying solder through a hole inside a soldering rod and melting it by heating the solder rod using an electric heating coil, characterized in that solder is supplied in the form of a rod, and the upper part of the end of the soldering rod is made spherical to smooth the resulting layer solder, using a soldering rod made of copper.
What is ultrasound?
Ultrasound is sound waves that travel through space like photons of light. However, unlike light waves, which can travel in a vacuum, ultrasound requires an elastic medium, such as a gas, liquid or solid, to propagate. It is noteworthy that the human ear perceives a limited frequency of sound waves, and by ultrasound scientists mean frequencies above 20,000 hertz. Despite the fact that the existence of ultrasonic waves has been known since 1883, its practical use began not so long ago. Thus, in 2022, technologies using ultrasound are used almost everywhere. And in the wild, ultrasonic waves help dolphins, bats, whales, tarsiers and rodents detect obstacles, navigate in space and communicate. Ultrasonic waves are also found as components of natural noise, for example in the noise of rain, wind, waterfalls and in the sounds that accompany lightning discharges, etc.
Ultrasonic welding is a technology used to join fabrics (without threads or glue) and many other materials, including plastic and metal.
Pulse soldering iron: device design
A pulse soldering iron is necessary for assembling (dismantling) elements of electrical and electronic products. The heating element is a tip, which is made of copper wire (diameter 1-3 mm) coated with other metals. The tip is heated by passing a low voltage current through it. The soldering iron consumes little electricity, since current passes through the tip only during soldering. The device has a mains voltage converter with a frequency of 18−40 kHz. The secondary (power) winding is connected to the current collectors of the tip.
The main difference between a pulsed soldering iron and a regular soldering iron is that it does not need to always be kept on to maintain the temperature. The tip is heated within a few seconds. It is precisely because of this that the device does not consume electricity most of the time.
Types of soldering irons:
- Induction;
- Ceramic;
- Pulse;
- Rechargeable.
DIY soldering iron: simple assembly diagrams
Before making a soldering iron with your own hands, you should determine what exactly it will be used for and what materials are available at home.
“Moment” from a house-saving lamp
Components of the device:
- Converter from an energy-saving lamp (power 40 W);
- Transformer;
- Copper wire;
- Frame.
The characteristics of the converter are suitable for a medium-power soldering iron. The safety of the device is enhanced by a standard fuse and overheating control on the thermistor. The circuit is very compact and can be placed in any housing.
The transformer is made independently. You can use a ferrite ring from a broken electrical transformer. The primary winding must be wound from 0.5 mm wire, the number of turns is 100-120. And the power one should be made of wire with a cross-section of 3 to 3.5 square meters. mm. You need to make one turn. We attach a tip made of nichrome or copper wire (1.5 - 2 mm) to it. The thickness of the last winding should be greater than the thickness of the tip. Next, you need to come up with a body for the device, make a switch, and the device is ready.
From a Chinese transformer
For manufacturing, you need either a working twelve-volt power supply, or one with a burnt-out secondary winding. Any Chinese device will do just fine.
It is necessary to remove the circuit from the case and check the serviceability of the parts. We do not touch the converter, since we only need to change the appearance of the transformer. Next, we remove the secondary winding and make a new one from copper wire (the cross-section should be 1.5-3 sq. mm). If the cross-section is small, fold the wire in half. What is important is the overall cross section, which will be at least three squares. The winding is equal to one incomplete turn. Then, carefully thread it into the transformer body, first bending it like a hairpin. The transformer is soldered to the control board, and the power winding must be fixed with dielectric glue (for example, cold welding). Next, we insert the circuit into the case.
A wooden handle from a regular soldering iron can be used as a handle. Other options are possible, given the compactness of the device as a whole. We insert a non-fixed switch into the handle. The operation of a pulse device is based on a short circuit of the secondary winding , as a result of which prolonged heating can lead to destruction of the transformer and a fire. For this reason, a fixed starter is not permitted. Next, you need to assemble the device completely and install the clamps for the tip (for example, inserts from a terminal box for wiring). This device is very compact and easy to use for small soldering jobs. Thanks to the replaceable tip, you can change its appearance.
These options are only a small fraction among the variety of schemes for manufacturing pulsed devices.
Ultrasonic soldering
Ultrasonic soldering is a flux-free soldering technology that does not require any chemicals and uses ultrasonic energy to solder materials such as glass, ceramics, composite materials, and metals that are difficult or impossible to solder using traditional means.
This technology is increasingly used when soldering together metal and ceramic parts included in the design of solar cells, as well as parts made of medical alloys with shape memory used in specialized electronic modules and sensor units.
Ultrasonic soldering has been mentioned since 1955 as a method for soldering aluminum and other metals without the use of flux.
This technology differs significantly from ultrasonic welding. The latter uses ultrasonic energy to join parts without adding any fillers, while traditional (and ultrasonic) soldering uses external heat to form the joint to melt metal fillers, i.e. solders. In this case, ultrasonic soldering can be performed using either a special soldering iron or a special soldering bath.
This process can be carried out either automatically during mass production or manually during prototyping or repair work.
Ultrasonic soldering was originally intended for joining aluminum and other metals, but today, with the advent of active solders, a wider range of metals, ceramics and glass can be soldered.
This technology uses either ultrasonic soldering irons with a tip with a diameter of 0.5-10 mm, or ultrasonic soldering baths. These devices use piezoelectric crystals to generate high-frequency (20-60 kHz) sound waves in layers of molten solder or in a bath of molten solder to mechanically destroy oxide films formed on the surfaces of the melt. In this case, the tips of ultrasonic soldering irons are simultaneously connected to the heating element, while the piezoelectric crystal is thermally insulated to prevent its destruction.
The tips of ultrasonic soldering irons can heat up to 450 °C during mechanical vibrations with a frequency of 20-60 kHz. Such a tip is capable of melting metal fillers of solder by exciting sound vibrations in the molten solder. At the same time, vibration and cavitation (pore formation) in the resulting melt allow solders to wet the surfaces of many metals and adhere to them.
The energy of sound waves generated by the tip of an ultrasonic soldering iron or an ultrasonic solder bath causes cavitation in the molten solder, which mechanically destroys the oxide films located on top of the layers of the solder itself and on the metal surfaces being joined.
Cavitation in a bath of molten solder can very effectively destroy oxide films on the surfaces of many metals, but it is ineffective when soldering to ceramics and glass, since the latter are themselves oxides, as well as to other non-metallic composite materials that cannot be destroyed, since they are base substance. In case of soldering directly to glass and ceramics, metal fillers for ultrasonic soldering must be doped with active elements such as indium (In), titanium (Ti), hafnium (Hf), zirconium (Zr), and rare earth elements (cerium/Ce, lanthanum/La and lutetium/Lu). Solders doped with these chemical elements are called "active solders" because they directly act on glass or ceramic surfaces to create adhesion to them.
Ultrasonic soldering technology is increasingly used due to its cleanliness, lack of flux and compatibility with active solders, and is intended for joining parts that do not allow the use of aggressive flux or consist of dissimilar materials (metals, ceramics or glass).
For effective adhesion to surfaces, the active solder's own oxide film, formed during its melting, must be destroyed, and ultrasonic vibration is well suited for this purpose.
Application
Benchtop ultrasonic baths are used for hot tinning of parts and leads of electronic components, and ultrasonic soldering irons are used for soldering and metallization of ceramic and ferrite materials. The use of modern electronic sources of ultrasonic vibrations makes soldering a reliable, environmentally friendly process and eliminates the use of fluxes.
For ultrasonic soldering processes in electronics, lead-free tin-based alloys have been sufficiently studied: double Sn-Zn, Sn-Bi, triple: Sn-Bi-In, Sn-Bi-Zn, Sn-In-Ag, Sn-Sb-Zn, Sn-Sb-Ag and quaternary alloy: Sn-Zn-In-Sb. All these alloys have a melting point in the temperature range 135 ... 220 ° C.
Fluxless ultrasonic soldering is an environmentally friendly process and is more economical since operations such as fluxing and cleaning, which require time and materials, are eliminated. Flux-free soldering in some cases is a necessary condition for internal installation and sealing of microelectronic equipment. Using ultrasonic metallization and soldering, materials are joined that are difficult to solder: nickel, aluminum, magnesium and titanium alloys, as well as non-metallic materials: ceramics, glass, ferrites. This creates the opportunity to save precious metals deposited on the dielectric surfaces of electronic components as metallization.
When choosing solders for ultrasonic flux-free soldering and tinning of various materials, one should take into account their ability to solder, the chemical affinity of the materials being soldered and the ability to create a high-quality connection according to the state diagram of the alloys. The use of lead-free solders with the addition of Zn, In, Ag leads to an increase in the adhesive activity of the melt and reduces their oxidation during ultrasonic soldering.
