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What Is an Ultrasonic Welder?

An Ultrasonic Welder is a mechanical device that uses the heat generated by friction between objects to weld them together.

It is mainly used for joining plastic materials and dissimilar metals.

Because welding is performed by frictional heat, it consumes less power than other heating-based welding methods. It offers easy automation and ensures high reproducibility, as well as a good appearance after welding because no adhesives are used.

Developed in the 1960s, Ultrasonic Welder has been in use for over 50 years. It typically consists of an oscillator and welding table or a transducer and horn. By applying simultaneous ultrasonic vibration and pressure, this device can quickly melt and bond resin and metal materials. Ultrasonic welding machines find extensive applications across various industries. Key features of this welding machine are that it does not use any adhesives, so the appearance after welding is beautiful, it is environmentally friendly because it uses instantaneous frictional heat to weld, so it consumes less power, and its easy to automate, so it is highly reproducible.

Uses of Ultrasonic Welder

The main applications of Ultrasonic Welders are as follows:

• Joining terminals and wiring.
• Joining plastic products.
• Joining dissimilar metals such as aluminum and copper materials.

Ultrasonic welding can be used to bond metals as well as plastics. Its also used to bond metal terminals and wiring, and metal wires inside IC chips.

Principle of Ultrasonic Welder

Ultrasonic Welder is a device in which a transducer, called a horn, applies a certain amount of pressure between the materials to be bonded. The vibration of the horn transfers energy to the bonded surfaces for welding.

The frictional heat generated between the surfaces of the bonded objects makes welding possible. Especially when the object to be welded is metal, the ultrasonic vibration causes the metal surfaces to rub against each other, destroying the oxide film on the surfaces and providing bonding strength.

Ultrasonic Welders consist of an oscillator and a transducer. The oscillator is a device that generates ultrasonic vibrations and is designed to have a constant amplitude so that the amplitude does not change depending on the type of material to be welded. By keeping the amplitude constant, the quality of the product after welding can be ensured. The transducer consists of a Langevin transducer (commonly known as a BL transducer) and a horn member that transmits the vibration. Ultrasonic Welders perform welding by propagating ultrasonic waves from the horn to the welded product.

Other Information on Ultrasonic Welder

1.Features of Ultrasonic Welder

Ultrasonic Welders tend to melt the heated material if the welding time is too long, while the resin tends to carbonize if the welding time is too long. Also, the pressure generated when the object to be welded is held by the horn reduces the welding time if the pressure is high, but too much pressure can also cause the object to stop melting. The important point is to control the three factors, namely, time, pressure, and heat, and ensuring they remain within an appropriate condition range.

Advantages of Ultrasonic Welding include the following:

• Applicable to virtually all thermoplastics.
• Continuous seam joining and simultaneous multi-point joining are possible.
• Low heat storage.
• Fluxless welding eliminates the need for cleaning processes, and no sparks, flames, or smoke are generated.
• No toxic substances are emitted during plastic welding.
• No consumable parts or materials, energy saving and low running cost.
• Capable of joining dissimilar metals.

While the following points are some disadvantages:

• Shapes that cannot be sandwiched by the horn, such as miscellaneous or three-dimensional shapes, cannot be joined.
• High amplitude may result in good weldability, but depending on conditions, scratches or cracks may occur on the resin.
• High pressure may prevent welding.

2. Ultrasonic Horn

An ultrasonic horn is a component that efficiently transfers vibration energy to the object to be welded. Ultrasonic waves are converted into mechanical vibration amplitude energy by a transducer, and then amplified by a transducer called a booster before being transmitted to the horn. The amplitude is gradually amplified and then optimized at the horn tip. By concentrating the ultrasonic vibration at the horn tip, the object is impacted 40,000 times per second (at 40 kHz).

Ultrasonic horns are available in the following types:

1. Step type: high amplitude and high stress type.
2. Catenoidal type: intermediate in amplitude and stress.
3. Exponential type: low amplitude and low stress.

Ultrasonic horn materials are used according to the purpose of welding, and the following materials are mainly used:

1. Aluminum alloy
2. Titanium alloy
3. Die steel

3. Mask Manufacturing Using Ultrasonic Welder

Ultrasonic Welders are also used in mask manufacturing. Ultrasonic welding machines use ultrasonic vibrations to melt materials and weld them together to produce the twill lines and engravings on masks. This process eliminates the need for threads and adhesives, simplifying the production process.

In addition, the mask can be welded to the mask body with ear strings made of different materials such as natural latex rubber for the rubber part and PE for the thread parts. This ensures that the mask can be manufactured with a single equipment. It is expected that the use of Ultrasonic Welders in mask production will increase in the future.

What Is a Measuring Microscope?

A measuring microscope is a dimensional measuring instrument that measures dimensions from images magnified by a microscope.

A measuring microscope is a combination of an optical microscope magnified at precise magnification. It also serves as template for comparative measurement, and an XY stage for precise movement of the workpiece on a plane. Measuring microscopes enable non-contact measurement, allows observation of contours and surfaces without damaging the workpiece.

Measuring microscopes generally use telecentric optics in their optical system. In recent years, there are specifications that employ an infinity-corrected optical system in the optical head to enable differential interference observation and simple polarized light observation.

Uses of Measuring Microscopes

Measuring microscopes are used for production and quality control of relatively small mechanical parts, electronic device parts, and semiconductor products. These measuring microscopes are suitable for the measurement of small parts and fine areas that are difficult to measure without microscope magnification.

In addition to dimensional measurement, the microscope can also be used for observation using polarized light and differential interference, for example, to detect flaws in semiconductor substrates. Due to the accuracy of its magnification, it is also useful for simple inspections to determine if a product is within tolerance by performing comparative measurements using a template.

Measuring microscopes can be used as both a measuring instrument and a microscope. Meanwhile, a single unit of measuring microscope can be used for a variety of purposes.

Principle of Measuring Microscope

Measuring microscopes can be classified according to the illumination method.

1. Transillumination

Transillumination is used for dimensional measurement by transmitting light and capturing the shadow of an object as a contour shape. It is used to measure contours. 

2. Vertically Reflected Illumination

Vertically reflected illumination shines light perpendicular to the surface of an object and observes the surface through the reflected light. Vertical reflected illumination can be used not only for dimensional measurement but also for observation of surface shape. 

3. Oblique Reflection Illumination

Oblique reflection illumination is an illumination method that illuminates light at an angle to the surface of the object to be measured. The feature of this method is that the contrast of the image is emphasized, resulting in a three-dimensional and sharp image. However, it is more likely to cause errors in dimensional measurement.

Other Information on Measuring Microscope

1. Telecentric Optics

Most measuring microscopes use telecentric optics for transillumination. Microscopes that do not use telecentric optics will make objects close at hand appear larger and objects farther away appear smaller.

This phenomenon is the same with cameras that we use in our daily lives. However, in dimensional measurement, this characteristic results in distant objects being measured smaller in relation to different parts in the height direction.

With a lens using telecentric optics, the image is blurred, but the size remains the same, even if the focus is shifted in the direction of the distance to the lens and the optical axis. Telecentric optics are indispensable for measuring microscopes, where dimensions are measured while observing with the microscope. 

2. Parallelization of Measuring Microscope

Measuring microscopes are used to measure by placing the object to be measured on the XY stage. Therefore, the measurement point can be anywhere within the operating range of the XY stage. In other words, no matter where the object to be measured is located on the XY stage, the XY stage can be moved to the measurement point.

Some angles or circle diameters to be measured may require a large movement of the XY stage, but the contour of the measurement object is never placed parallel to the movement of the XY stage without special adjustment. Therefore, it is necessary to make the movement of the XY stage and the reference edge of the measurement object parallel before measurement.

If the measurement object and the XY stage are not parallelized, large errors will occur when measuring angles and parallelism. Therefore, calculations are required to compensate for the measurement results. In recent years, manufacturers have a lineup of measurement devices that create a coordinate system on the XY stage and calculate from the coordinates of the origin and measurement points. By using these devices, the man-hours required for parallelization can be reduced. 

3. Field of View of Measuring Microscope

While it is important for a microscope to be able to observe an object under large magnification, it is also important to be able to obtain a wide field of view at a time. The field of view is the area that can be observed at one time using a microscope. The field of view is determined by the diameter of the eyepiece.

The size of the field of view is called the number of fields of view, and the actual field of view represents how much of the surface of the object being measured is visible within the field of view.

The relationship between the actual field of view and lens magnification is as follows:

Actual field of view = Number of fields of view of eyepiece / Magnification of objective lens

As can be seen from the above formula, if the number of fields of view of the eyepiece is the same, the range of the actual field of view becomes narrower as the magnification of the objective lens becomes larger. This indicates that there is a trade-off between increasing the magnification of the objective lens to magnify the object to be measured and the range that can be viewed at one time.

To increase the actual field of view, the diameter of the eyepiece must be increased or the magnification of the objective lens must be decreased. However, there is a limit to reducing the objective lens magnification because of the magnification required for measurement. For this reason, measuring microscopes are equipped with an XY stage and a counter that displays the amount of movement, as well as other devices to measure areas that do not fit into the field of view.

What Is a Laser Module?

A laser module is a set of devices that produce a laser light source, which is required for various devices that operate using lasers.

Today, there are many devices that use lasers, and in particular, laser light sources are indispensable for measurement devices, position detection devices, and various sensors. Most lasers used for measurement purposes are blue, green, or red lasers in the visible light range, but there are also lasers used for processing purposes that deviate from that wavelength range, and they are classified from Class 1 to Class 4 according to the degree of danger they pose.

Uses of Laser Modules

Applications of laser modules vary depending on the wavelength, but in general, they are used for measurement purposes, pointers, light sources for DVD pickups, wiring of semiconductor parts, and mark printing on resin materials and other materials.

Red lasers are mainly used in measuring instruments, such as microscopes and interferometers. For this reason, many laser modules that can stably emit red lasers for measurement equipment are now commercially available. Light sources in the visible light range are relatively safe as long as they are not greatly amplified, so they are also used in laser pointers and projectors.

On the other hand, lasers of various wavelengths are used in laser processing machines. Depending on the wavelength, the materials that can be processed and the damage to the workpiece will vary.

Principle of Laser Modules

The principle of the laser module lies in the use of elements suitable for the wavelength and phase of the laser light required, and in the utilization of the physical transition of energy levels of the elements, called induced emission.

To obtain light of a specific wavelength, a medium composed of an element is prepared. When this element lowers its level from the excited state, it emits a certain amount of electromagnetic energy, and a light source with a wavelength corresponding to that energy is obtained.

In order to align the phases of this light source in the laser module, it is necessary to drop the levels of many excited elements at once. This is done by using a physical phenomenon called induced emission. Induced emission is a phenomenon in which, when light equivalent to the energy difference between the excited level and the defined level of the element is incident, the electrons in that area also emit energy in response to the incident light. This phenomenon will result in light of the same phase.

In order to perform many induced emissions at the same time, the laser module is configured to extract a laser light source of a certain wavelength by repeating the cycle of excitation of the entire element to an excited state at once and induced emission.

Other Information on Laser Modules

1. Class Classification of Laser Light Sources

Laser light sources are classified according to their safety management, and are classified according to the stage from Class 1 to Class 4. For example, Class 1 is not a safety issue and no special measures are required, but Class 4 is a high power laser that handles CW of 0.5W or more, and there are concerns about burns and damage to the skin and eyes, even if the light is reflected.

Adequate safety measures, including protective equipment, are required, and products are usually labeled with a warning label corresponding to the laser class. Some products are equipped with protective covers, including interlocks, so that even Class 4 lasers can be handled as Class 1 lasers. 

2. Examples of Laser Module Wavelengths

Laser modules are commercialized in a variety of wavelength values. Visible light is handled with a lower limit of purple around 380 nm and red around 780 nm, depending on the application, and red lasers are widely used for pointer applications and measuring instruments.

On the other hand, a typical example of a laser source for processing applications is the CO2 laser, which has the longest wavelengths of 10.6um and 9.6um.

What Is a Vacuum Furnace?

A vacuum furnace is a furnace capable of vacuum heat treatment processing.

Since the object is heated in a vacuum furnace, the surface of the object can be processed without oxidizing it. Decarburization is prevented and the luster of stainless steel and other materials can be maintained after heat treatment.

Also, because of the high surface cleanliness, bonding of dissimilar metals can be processed cleanly. A major feature of this process is that distortion can be reduced because of the gradual cooling process from heating to cooling.

This processing method emits less carbon dioxide and reduces variation in dimensions and hardness. In some cases, heat treatment is performed in a Vacuum Furnace with nitrogen gas flowing through it.

Uses of Vacuum Furnace

Vacuum furnaces are mainly used for processing metals and semiconductors.

The following are examples of vacuum furnace applications:

• Quenching, tempering, and sintering of metals
• Brazing of evaporators, etc.
• Annealing

The following are also examples of products manufactured in vacuum furnaces:

• High-grade steels for carbide tools
• Materials for electronic products such as magnets and capacitors
• Automotive parts and industrial machinery parts

Metals that require special features are fabricated in vacuum furnaces. Metals treated in vacuum furnaces are characterized by high luminosity, and surface oxidation and impurities can be reduced.

Vacuum furnaces have many advantages, but they also have the disadvantage of high maintenance and initial installation costs.

Principle of Vacuum Furnaces

Vacuum furnaces use a combination of oil rotary pumps and turbo molecular pumps to exhaust the air inside the furnace and maintain a high vacuum. Heating in the absence of oxygen in a high vacuum prevents oxidation.

1. Vessel Material

Stainless steel is generally used as the furnace vessel material; it can be heated to 1,000°C to 2,300°C and is heated by metal heaters such as tungsten, molybdenum, and silicon carbide.

Smaller furnaces are also available in which the object is heated in a tubular furnace made of alumina or quartz glass. Kanthal wire is used as the heater material, and the furnace can heat up to 700°C to 1,600°C.

2. Cooling Method

Cooling methods include natural cooling, gas cooling, and oil cooling. For high temperatures, the vessel is double-layered and water-cooled. High temperatures are measured externally with a radiation thermometer.

In a standard vacuum furnace, heating and cooling are performed in the same chamber.

 Structure of Vacuum Furnaces

Vacuum furnaces perform heat treatment of heat-treated products through the three processes of conveyance, heating, and cooling. There are two main types of furnaces, the “one-chamber type” and the “multi-chamber type,” depending on the type and purpose of the heat-treated parts.

1. One-Chamber Vacuum Furnace

In the one-chamber type vacuum furnace, the operator transfers and places the product to be treated in the furnace, and the heating and cooling processes are performed in a single chamber. Since the heating and cooling processes are performed in the same room, the furnace must be able to withstand sudden temperature differences. Heat-resistant stainless steel or carbon materials are used for the heater and structural components.

Because of its simple structure, the lineup of furnaces is extensive, ranging from small to large sizes. For cooling, natural cooling or inert gas cooling with nitrogen or other inert gases is used to prevent contamination of the furnace interior and heat-treated products. The cooling gas outlet structure and stirring fan enable uniform cooling with minimal contamination.

Therefore, it is suitable for processing products that are sensitive to surface contamination or deformation. On the other hand, the disadvantage is low productivity because the next product to be heat-treated cannot be loaded until the previous treatment is completed.

2. Multi-Chamber Vacuum Furnace

The multi-chamber type vacuum furnace has a structure in which the conveying, heating, and cooling processes are performed in two or more chambers. Heating and cooling are basically completed automatically, as per the settings once the product is fed into the transfer chamber. It is possible to control the temperature in each zone, or to set up multiple heating chambers for small batches and stagger the processing time.

The above innovations can improve productivity. By making cooling in a separate chamber, liquid refrigerants with high cooling capacity, such as oil, can be selected. High cooling capacity can be maintained because the cooling chamber is not heated.

Even metallic materials with low hardenability and sensitive to cooling rates can be cooled to a high level of performance. On the other hand, cleaning is required after heat treatment due to contamination of the treated material by the refrigerant. There is also a risk of distortion and cracking due to the high cooling rate.

Other Information on Vacuum Furnaces

Carbon Components of Vacuum Furnaces

Carbon components such as carbon graphite and C/C composite are used in Vacuum Furnaces. They are used for heating elements, structural materials, and heat treatment jigs.

Carbon materials have high heat resistance, up to 3,000°C. They are lightweight and have a low coefficient of thermal expansion. They are characterized by their light weight, low coefficient of thermal expansion, low deformation due to thermal fatigue, and low heat capacity.

Its light weight allows for increased loading capacity of heat-treated products and reduced setup load. The low deformation resistance also leads to lower running costs. The low thermal capacity and high energy-saving effect provide many productivity-enhancing benefits.

However, a disadvantage is that carbon volatilization during heating causes contamination of the furnace interior and heat-treated parts. The cooling method is also limited to gas cooling only.

What Is a Conveyor Screw?

A conveyor screw is a conveyor that can transport granular objects by rotating helical screw blades.

It does not have a feeding function, and is a product made specifically for conveying only as a conveyor. Due to its structure, it is capable of transporting at an incline, and is characterized by its resistance to contamination by foreign matter and leakage of transported materials.

Taking advantage of the features of the screw wings, which are shaped like a series of spirals, it is possible to feed two or more substances at the same time and mix and transfer them while agitating, in addition to conveying. It can be used in combination with a feeder to supply a fixed amount, or to cool and heat at the same time.

Conveyor screws are efficient, compact, and can be used as part of a complex process. They are also easily installed and removed, and mobile products are available.

Uses of Conveyor Screws

Conveyor screws are used in a variety of industries for powder conveying applications because of their simplicity of construction and efficiency.

A typical industry is the building materials industry. They are used to mix and transport raw materials such as cement, sand, water, and crushed stone for the purpose of manufacturing concrete. It is one of the main raw materials for concrete and is widely used in construction and civil engineering projects.

In the food sector, it is used to transport agricultural products such as feed and grains. In the mining industry, it is used to transport cement and coal. In some cases, they are used for ash removal from boilers.

In the chemical industry, they are used to transport granulated chemicals. One example is the transport of calcium carbonate from tanks to mixing tanks. They are also used in the pharmaceutical and other fields, where they are responsible for mixing and conveying.

Principle of the Conveyor Screws

The principle of a conveyor screw is a machine that feeds material by rotating a helically bent feed screw (screw). A conveyor screw consists of a screw, housing, and drive unit.

1. Screw (Feed Screw)

The screw is a spiral-shaped part that feeds the material. As the screw rotates, the material is pushed forward.

The screw diameter and pitch (angle of rotation of the screw) are designed according to the type and amount of material to be conveyed. By adjusting the shape and rotation speed of the screw, the amount and speed of material being pumped can be controlled.

2. Housing

The housing is a cylindrical outer shell that covers the screw. It contains the material to be transferred. The shape and size of the housing are designed according to the size of the screw and the type of material to be transferred. The material to be transferred moves inside the housing along the screw’s spiral groove.

3. Drive Unit

The drive unit, such as an electric motor or engine, is used to rotate the screw. The drive unit rotates the screw to feed the material.

In most industrial applications, three-phase induction motors are used. Among three-phase motors, 200V products are most common. By using an inverter or other device, the rotational speed of the drive unit can be varied to change the conveying speed.

How to Select a Conveyor Screw

When selecting a conveyor screw, select the appropriate equipment based on the object to be conveyed and the distance to be covered.

First, the selection should be based on the material to be conveyed, such as powder or granules. In most cases, conveyor screws are used to transport powders, so other transport methods should be considered for liquids and other materials. The shape and material of the screw differs depending on the type of material to be conveyed.

Screw size and housing size also vary depending on the amount of material to be transported. We accurately ascertain the amount of material to be conveyed and select equipment with the necessary conveying capacity.

In addition, the range of application of conveyor screw is relatively short. Depending on the distance to be conveyed, multiple conveyor screws may need to be connected. It is necessary to consider the number and arrangement of the required conveyor screws according to the distance to be conveyed.

What Is a Screw Anchor?

A screw anchor is an anchoring component that utilizes screws for fastening and securing purposes. In construction, anchors are essential for attaching base materials to other materials or for connecting new materials to existing ones. There are primarily two types of anchors: pre-attached and post-attached, with post-attached anchors being specifically referred to as “post-attached anchors.”

Uses of Screw Anchors

Screw anchors are widely used in construction to attach metal components to concrete foundations and structures. Their applications range from installing handrails and column legs in parking garages to bicycle parking facilities, signs, solar panels, vending machines, and water pipes. They also play a crucial role in adding earthquake-resistant features to older buildings, installing protective railings on bridges and roads, fenders and vehicle stops in harbors, and tunnel lighting.

Principle of Screw Anchors

Screw anchors are installed by first fixing the anchor to the base material, then attaching other components to the anchor’s threaded portion. Unlike typical screws that rely on axial force for their anchoring strength, screw anchors generate a fixing force through shear stress between the base material and the anchor. This shear stress arises from the engagement of the screw’s threads with the base material, providing resistance against separation forces.

Other Information on Screw Anchors

1. Types of Anchors

Beyond screw anchors, the construction industry recognizes three major types of anchors: metallic, adhesive, and others. Metallic anchors, including metal diffusion anchors, secure themselves by expanding against the base material. Adhesive anchors are fixed in place by an adhesive agent cured within a pre-drilled hole in the base material.

2. Failure Modes of Post-installation Anchors

Post-installation anchors, including screw anchors, may fail in one of three modes: rupture of anchor reinforcement (yield failure of the anchor), cone failure (failure of the base metal), or anchor pullout. The mode of failure is determined by the weakest link in the anchoring system, whether it be the material strength of the anchor, the strength of the base metal, or the anchorage strength itself.

What Is a Switching Regulator?

A switching power supply (SMPS) is a power supply that incorporates a highly efficient power conversion circuit called a Switching Regulator.

Electronic devices with ICs and microcontrollers require stable direct current with minimal voltage fluctuation. There are two types of regulated power supplies: linear power supplies and switching regulators, but linear power supplies have been the most common.

In the case of linear power supplies, the circuit is simple. It converts a 100 V AC voltage into a constant AC voltage and rectifies the AC current by utilizing the diode’s property of flowing forward current but not reverse current. It further uses a capacitor to smooth it out. However, this had the disadvantage that it did not allow power supplies to be made smaller or more efficient.

Switching regulators have solved this problem. While linear power supplies convert commercial alternating current to voltage and then rectify it, switching regulators do the exact opposite: they rectify commercial alternating current to DC and then convert it to voltage.

Then, by switching on and off, it is converted into pulse wave AC and fed into a high-frequency transformer, which is the mechanism of switching regulator.

The feature of switching power supplies is that they are smaller and lighter, but their circuits are more complex.

Uses of Switching Regulators

Compared to conventional linear power supplies, switching regulators have much more complex circuits, but they have the advantage of being extremely compact due to the use of ICs for the stabilization circuit.

The large and heavy power transformer (a device that uses electromagnetic induction to convert the height of AC power voltage) is not installed, as in the case of a simple power supply, and this has made it possible to reduce the size and weight.

Because of this compactness and light weight, applications for switching regulators include AC adapters for cell phones. They are also highly compatible with small electronic devices such as PCs and tablets, which are often carried around.

Recently, in order to further promote miniaturization, high-power and high-efficiency GaN devices have been incorporated into switching regulators for AC adapters to realize even smaller AC adapters compared to conventional Si devices.

Principle of Switching Regulators

The principle of switching regulators is the opposite of the conventional linear power supply. Linear power supplies use a transformer to convert commercial current to voltage and then rectify it, whereas switching regulators first rectify commercial alternating current to DC and then convert it to voltage. However, once rectified, voltage conversion cannot be performed using a transformer.

Therefore, in switching regulators, the rectified current is converted into pulse-oriented AC by high-speed switching of semiconductor elements such as transistors and MOS FETs, and then fed into a high-frequency transformer. This increases the number of components and circuits required and makes them more complex, but this complexity is the key to switching regulators.

There are several types of control methods for switching regulators, the most common of which is the PWM (pulse width modulation) method. PWM is a method of stabilizing voltage by adjusting the on-time of the switching on/off cycle, or the width of the pulse wave, so that the area of each pulse is the same. Switching regulators can also be said to increase efficiency because the output can be adjusted by switching on and off.

In addition, since the pulses of switching regulators are high-frequency, ranging from tens to hundreds of kHz, the transformer can be small and lightweight. However, high frequencies increase the loss of the iron core, so a ferrite core is used. This improves power supply efficiency and saves energy.

The ferrite core has a core rod made of a material called ferrite that is attached to the cable so that it wraps the cable. This absorbs the magnetic field generated by the high-frequency noise current flowing through the cable and converts it into heat, thereby reducing noise.

The weak point of switching regulators is the generation of noise due to high-speed switching, which is expected to be reduced by ferrite technology.

Other Information on Switching Regulators

1. Frequency of Switching Regulators

Switching regulators convert the output voltage to a specified voltage value by adjusting the ON/OFF time of the switching operation using semiconductor elements. The frequency of the signal that controls this switching is called switching frequency. 

2. Reason Why 24V Voltage Is Often Used

In electrical products that use switching regulators, the output voltage required for the power supply is often 24 VDC. The reason for this is that control circuits require that voltage, although there are various theories.

One theory is that since DC was once often powered by batteries, it was determined by an integral multiple of the 1.5V of a dry cell battery cell. In small devices, 6V, 9V, 12V, etc. are also used, but these are also integer multiples of 1.5.

In the days before PLCs (programmable controllers) replaced control circuits used in factory automation, circuits consisted of electromagnetic relays, and the voltage was used to turn on the relays.

As a remnant of this, 24V is still often used today. There are also other reasons such as the fact that 24 VDC is more resistant to noise environments. 

3. Noise in Switching Regulators

Switching regulators use switching elements to turn current on and off at high speed, so it is inevitable that they generate high-frequency noise.

The history of the development of switching regulators has been one of increasing efficiency and at the same time, noise suppression has been a must. Modern switching regulators are equipped with various noise suppression measures.

Switching regulators are themselves a source of noise. Noise is not only added to the output power line, but also becomes electromagnetic waves that affect electronic equipment.

The following methods are available for noise suppression:

• Reflection
  Using inductors and capacitors as filters to prevent noise components from being transmitted
• Absorption
  Absorbing noise with ferrite cores, etc. and converting it into heat or other energy
• Bypass
  Dropping noise to ground with capacitors, etc.
• Shield
  Radiated noise components are dropped to the ground with a metal case or absorbed with a ferrite material or other radio wave absorbing material.

4. Detailed Examples of Noise Suppression for Switching Regulators

The most common types of noise are common mode noise and differential noise.

Common mode noise
This is noise that leaks through parasitic capacitance generated between the switching regulator circuit board and the equipment chassis and returns to the power supply side through the GND as a loop path.

Differential Noise
In this case, the noise is current noise from a noise source entering the switching regulator circuit in series with and returning to the power supply side via the power supply line. As the name implies, the direction of each noise current at the positive and negative poles of the power supply is opposite and is also called normal mode noise.

It is called differential noise because the direction of the noise current at the positive and negative poles of the power supply is the same for each.

Generally speaking, common mode noise is the more radiated of the two types of noise, but countermeasures must be taken for both if the allowable noise level is exceeded. The first method is to shorten the cable length of the path or to use stranded cables.

For more serious countermeasures, a noise filter must be added. Choke coils are effective against common-mode noise. A bypass capacitor to ground, called a pass capacitor, is also used. Differential noise suppression is achieved by connecting capacitors between power lines flowing in opposite directions.

What Is Zirconia?

Zirconia is the generic name for zirconium oxide, an oxide of zirconium.

Its chemical formula is ZrO2, and it is classified as a ceramic. Its extremely high melting point and heat resistance make it suitable as a raw material for cutting and polishing tools and refractories. Zirconia is also used in dental materials and ceramic knives as a familiar example.

Uses of Zirconia

Zirconia has a high melting point and is resistant to chemical erosion, making it suitable as a material for cutting and polishing tools and refractories such as crucibles and furnaces. Zirconia is also used in ceramic knives because of its hardness, flexibility, and strength.

Among zirconia materials, tetragonal zirconia is used as a raw material for ceramics and as grinding balls for electronic components.

Cubic zirconia also has oxygen ion conductivity and is used as a solid electrolyte membrane in fuel cells.

Principles of Zirconia

Zirconium is an element with atomic number 40, and its oxide, zirconium oxide, is called zirconia and classified as a ceramic. At room temperature, it forms the most stable monoclinic crystal structure, but as the temperature is increased, the material changes sequentially to tetragonal and cubic crystals.

Properties of Zirconias

Zirconia (ZrO2) has a melting point of about 2,700°C. It has many features such as low thermal conductivity, heat resistance, corrosion resistance, and high strength. On the other hand, zirconia is susceptible to degradation due to changes in crystal structure and volume caused by changes in temperature.

Oxides such as yttrium oxide (Y2O3), calcium oxide (CaO), cerium oxide (CeO2), and magnesium oxide (MgO) are suitable stabilizers for zirconia. By adding these oxides to react and form a solid solution in the crystal structure, the stable existence of cubic crystals at room temperature becomes possible. Zirconia with a stable cubic crystal at room temperature is called stabilized zirconia or partially stabilized zirconia.

1. Stabilized Zirconia

Stabilized zirconia is a good conductor of oxygen ions at high temperatures due to its high oxygen vacancy lattice. It is also chemically stable and is being investigated as a solidification base material for high concentration TRU waste.

2. Partially stabilized Zirconia

Partially stabilized Zirconia is generally made by reducing the amount of oxide added compared to stabilized zirconia.

Other Information on Zirconia

1. Dental Applications of Zirconia Ceramics

When 3 mol% yttrium oxide is added to partially stabilized zirconia, Y-TZP (Tetragonal Zirconia Polycrystal), which has almost 100% tetragonal crystals at room temperature, is used as a dental material. Zirconia is a highly hard material, which makes it less workable when fully sintered.

For this reason, zirconia products used for dental applications are generally made by cutting blocks in a semi-sintered state, which is relatively easy to process, followed by full sintering.

2. Zirconia manufacturing method

There are two main methods of zirconia production: wet refining and dry refining. The raw materials for both methods are zirconium ores such as zircon and adelite. The first process in the wet refining method is to melt the selected ores with caustic soda, and then decompose. After further processes such as washing and filtration, the resulting zirconium hydroxide is calcined and pulverized to produce zirconia powder. In the dry refining method, on the other hand, the ore is crushed to remove impurities and then beneficiated repeatedly to produce pure zirconia.

3. The difference between Zirconia and metals

The difference between zirconia and metals is that zirconia is an oxide of zirconium metal, which is a ceramic due to covalent bonds stronger than metallic bonds.

• Resistance to corrosion
  Metals tend to combine with corrosive elements in the environment, such as oxygen and sulfur, and corrode relatively easily, but zirconium rarely corrodes.
• High hardness and heat resistance
  Zirconium is formed by covalent bonds that are stronger than metallic bonds, making it extremely hard, strong, and difficult to deform, and its high melting point (1,855°C) also makes it highly heat resistant.

On the other hand, unlike metals, zirconia is not ductile and does not elongate, making it vulnerable to strong impacts, and in some cases, it may crack.

4. Difference between Zirconia and Silica ceramics

Zirconia has become widely used in dentistry in recent years, as mentioned above, because of its hardness, flexibility, and non-corrosive properties compared to metals. However, silica-based ceramics have the disadvantage of being hard but easily fractured when compared to real teeth.

Zirconia is so hard that it is called an artificial diamond, and its hardness is about 10 times that of conventional ceramics, making it extremely durable. However, in recent years, the variations have increased, and in dental applications, it is also being used in front teeth, which requires a high level of aesthetics in dental applications.

5. Disadvantages of Zirconia in dental applications

Although dental zirconia is white in color and esthetic, it is less transparent than silica ceramics, and the lack of color variation has been considered a demerit. Recently, however, the number of variations has increased, and zirconia is now being used for anterior teeth, which requires a high level of aesthetics in dental applications.

However, zirconia is extremely hard, about 10 times harder than ceramics, and if the bite is incorrectly adjusted, it can shave the teeth to which it is being meshed, which is a demerit that needs to be improved. In addition, to its hardness of zirconia, it makes it difficult to process and shape manually by dentists, and because it is shaped by a computerized machine, it is less precise than ceramics.

Finally, another disadvantage is the high cost of treatment. This is due to the high price of high-quality zirconia itself used in dentistry and the fact that it is an out-of-pocket treatment not covered by insurance, but this is a point that should be improved in the future.

What Is a Jumper?

A Jumper is a generic term for a metal wire, metal terminal, or pin that shorts two points on a breadboard or PCB.

A breadboard is a board on which electronic circuits can be built simply by inserting electronic components and jumper wires into the holes. Each of the electronic components that make up a circuit has a specific role, and these components must be connected correctly for the circuit to work properly.

Jumpers make it easy to directly connect two points on a circuit.

Uses of Jumpers

There are two types of jumpers commonly used: one is a conductor type jumper wire and the other is a set of jumper pins and a jumper switch.

1. Jumper Wire

Jumper wires are used to easily build circuits in combination with breadboards. They are useful in electronic construction because they can be used to build circuits simply by inserting components and jumper wires into holes in the breadboard, eliminating the need for complicated soldering. 

2. Jumper Pins and Jumper Switches

Jumper pins and jumper switches are two small components that come as a set and are used to switch the circuit operation on the PCB or to expand the functionality of the PCB. The signal connection destination is switched by inserting or removing jumper switches from the jumper pins depending on the application.

This is used not only to switch or expand functions, but also to disconnect circuits with abnormalities. Jumper pins are sometimes called pin headers. A jumper switch is sometimes called a jumper cap.

Principle of Jumper 

Jumpers utilize the property that an electric current flows (short-circuiting) when metals make direct contact with each other.

1. Jumper Wire

A jumper wire is a simple metal wire. The ends are often shaped for easy connection to a breadboard. Some are shaped like sockets to connect to jumper pins on the PCB.

Wires other than the connection part are covered with a vinyl sheath. Typical wiring thickness is about 1 mm. If the amount of current to be handled in a circuit is large, thicker wiring may be used to lower wiring resistance.

2. Jumper Pins and Jumper Switches

Most jumper pins take the form of metal terminals arranged in a regular pattern with a 2.54mm pitch. There are two types of jumper pin structures: the dip structure, which is suitable for inserting into a breadboard or PCB, and the SMD (Surface Mounted Device) structure, which is suitable for surface mounting on a PCB. These two types are used according to the circuit and PCB design policy.

The metal plug is covered by a plastic outer shell, which makes it easy to connect and disconnect with bare hands. Inside the jumper switch is wiring that shorts the jumper pins when they are inserted into two adjacent jumper pins.

Other Information on Jumpers

1. Precautions for Handling Jumpers

Jumpers are useful for testing circuits and creating experimental circuits because they allow you to easily switch circuit operations and add functions. However, if a jumper is set incorrectly, the operation of the circuit may become unstable or malfunction.

When using jumpers, it is necessary to check the expected circuit behavior and appropriate jumper settings every step of the way. 

2. Items on Which Jumpers Cannot Be Mounted

Due to their shape and size, jumpers cannot be mounted on PCBs for consumer devices such as smartphones, which require small size, high density, and low profile. In such devices, PCB designs may be made so that wiring can be switched with 0 Ohm resistors instead of jumpers.

On the other hand, desktop PCs and devices for industrial equipment often have plenty of space, and jumpers are usually installed on the PCB.