Dongguan Ampfort Electronics Co., Ltd.

Smart Circuit Protection Experts Around You

I Switching power supply thermistor case

Compared with other thermistor manufacturers, the thermistor customized by Dongguan Ampfort Electronics has the characteristics of high power, strong surge current suppression, high reliability, long life, and low residual resistance. It is a representative of high cost performance, high reliability power NTC thermistor, with good quality and superior performance. Support special customization to meet our needs for different purposes. And their services are also very considerate, providing multiple service channels, pre-sales consultation and after-sales product use tracking, and truly realize a full service system.

Because the switching power supply has the advantages of high efficiency, low energy transmission loss, flexible and changeable output, and small space occupied by general linear power supplies, it has been widely used. Up to now, switching power supplies are used almost without exception for the power supply of large electronic equipment, small household appliances, and the power supply of LED lights. It is the most commonly recognized high-efficiency and low-power power supply method, but low Power consumption. High-efficiency conversion (AC-DC) comes at a price. Switching power supplies will also cause a lot of troubles in practical applications, such as: EMC problems, power-on surge current problems, high-voltage and high-current conditions, and high-value key components are easy Frequent damages and early failures will cause the entire power system to be damaged prematurely, and electrical appliances or equipment cannot be used. This is one of the most troublesome things for the majority of circuit designers, especially power supply design engineers.

II New energy vehicle thermistor application case 

The thermistor for new energy vehicles is selected from Ampfort Thermistor. Ampfort was awarded the "National High-tech Enterprise" as an electronic component brand integrating R&D, design, production and sales. The 37 engineers in the R&D team have more than 10 years of experience in the electronics industry, and have long-term cooperation with China Academy of Metrology, Nanjing Institute of Technology, Hefei University of Technology and other institutions; parameters and sizes can be customized according to customer requirements, focusing on customer special needs (Mechanical and electrical coordination, electronic product transformation and upgrading, plan provision, etc.).

The temperature-measuring NTC thermistor produced by Ampfort has mature application schemes in automobile water temperature detection, engine temperature rise detection, and battery core temperature rise detection in battery management systems. Power type The NTC thermistor MF72, MF73 and other series have also been fully used in electric vehicle charging piles. As shown in the figure, it is a charging pile circuit with a power of 2KVA that is currently installed and used for electric vehicle charging piles.

Ampfort focuses on the research and development, production and sales of a full range of sensitive components such as NTC thermistors, NTC temperature sensors, Pt platinum resistance temperature sensors, PTC thermistors and zinc oxide varistors. It is a semiconductor sensor that has won the domestic industry. One of the component manufacturers.

III Application case of power NTC thermistor for household appliances

It is well known that power NTC thermistors play a major variability role in suppressing the instantaneous surge current of the power supply system.

The application of power NTC thermistors in the power supply system of household appliances represented by color TV sets has been widely used since the end of the 1980s with the popularization of large-scale color TV technology. NTC thermistors The use of suppressing surge current to absorb large current peaks has made the TV's power supply system a key component. Security devices have long life cycles. Today, this application seems to continue to be widely used in many office electronic equipment in color televisions and display computer systems, and with the continuous development of electronic and electrical equipment, it is expanding its application to more fields.

With the help of our Ampfort Electronics team, a household appliance manufacturer that enjoys high brand influence both abroad and domestically has recently successfully applied the series of power NTC thermistors produced by our company to wall breakers, In the product of the soybean milk machine, the motor control system plays a major role in protecting the power supply system of the product.

Our company is one of the few domestic backbone enterprises that focus on R&D and production of NTC resistors. After 18 years of development, the company has a team of full-time R&D, testing and manufacturing technicians who have been deeply involved in the field of NTC thermistors for 18 years. It can provide a complete power supply for the power supply system designers of various enterprises and institutions, and a complete set of solutions for the suppression of inrush current in the motor system.

Remember me, Ampfort Electronic Co., Ltd. We only make excellent NTC !

Dongguan Ampfort Electronics Co., Ltd. is a comprehensive enterprise professionally engaged in R&D and production of various protection components, including thermistors, temperature sensors, varistors, fuses and related accessories, fixed resistors, thermostats, composite protectors, discharge tubes, diode,triode,inductor,magnetic beads, etc., as well as agency of famous brands. Headquartered located in Dongguan City Liwu Industrial Park with convenient transportation access. All products adopt international quality standards and our products are sold to overseas with good reputation in different market.

NTC thermistor manufacturing starting materials are different oxides of metals such as manganese, iron, cobalt, nickel, copper and zinc, to which chemically stabilizing oxides may be added to achieve better reproducibility and stability of the NTC thermistor characteristics.

The oxides are milled to a powdery mass, mixed with a plastic binder and then compressed into the desired shape. The blanks are then sintered at high temperatures (between 1000 °C and 1400 °C) to produce the polycrystalline thermistor body. Disks are contacted by baking a silver paste onto the flat surfaces. Depending on the application, the thermistors are fitted with leads or tab connectors, coated or additionally incorporated in different kinds of housing. Finally the thermistors are subjected to a special aging process to ensure high stability of the electrical values.
The major production process for temperature measurement Leaded NTC thermistor is as following:

Incoming Inspection

All raw materials, after being received in, are inspected to verify that their physical and electrical attributes are acceptable. A unique ID# is assigned and used for lot traceability.

Raw Material Blend

NTC thermistor manufacturing begins with the precise blending of raw materials into an organic binder solution. These raw materials are powdered transition metal oxides such as manganese, nickel, cobalt, and copper oxides. Other stabilizing agents are added to the mix as well. The oxides and binders are combined using a wet process technique called ball milling. During the ball milling process, the materials are blended and the particle size of the oxide powders are reduced. The completed homogeneous mixture has the consistency of a thick slurry. The exact composition of the various metal oxides and stabilizing agents determines the resistance-temperature characteristics and resistivity of the fired ceramic component.

Tape Cast

The "slurry" is distributed over a moving plastic carrier sheet using a doctor blade technique. The exact material thickness is controlled by adjusting the height of the doctor blade above the plastic carrier sheet, the carrier sheet speed, and by adjustment of the slurry viscosity. The cast material is dried as it is carried through a long tunnel oven at elevated temperatures on a flat casting belt. The resulting "green" tape is ductile and easily formable. The tape is then subjected to quality inspection and analysis. This thermistor tape is cast in a wide range of thicknesses ranging from as thin as 0.001" to over 0.100" dependent upon the particular component specification.

Wafer Formation

The cast tape now is ready to be formed into wafers. When thin material is needed, the tape is simply cut into small squares. For thicker wafers, the tape is cut into squares which are then stacked one on top of another. These stacked wafers are then laminated together. This allows us to produce wafers to virtually any thickness required. The wafers then go through additional quality testing to ensure high uniformity and quality. Subsequently, the wafers are subjected to a binder burn out cycle. This process removes most of the organic binders from the wafer. Precise time/temperature controls are maintained during the binder burn out cycle in order to prevent unfavorable physical stresses on the thermistor wafers.

Sinter

The wafers are heated to very high temperatures in an oxidizing atmosphere. At these high temperatures, the oxides react with one another and fuse together forming a spinel ceramic matrix. During the sintering process, the material densifies to a predetermined degree and the grain boundaries of the ceramic are allowed to grow. A precise temperature profile is maintained during the sinter process in order to avoid fracturing of the wafers, and to ensure the production of finished ceramic capable of producing components with uniform electrical characteristics. After sintering, the wafers are again subjected to quality inspection and the electrical and physical characteristics are documented.

Electrode

Ohmic contact to the ceramic wafer is obtained using a thick film electrode material. The material is typically silver, palladium-silver, gold, or platinum depending upon the application. The electrode material is comprised of a mixture of metal, glass, and various solvents and is applied to the two opposing surfaces of the wafer or chip by screen printing, spraying, or brushing. The electrode material is fired onto the ceramic in a thick film belt furnace and an electrical union and a mechanical bond forms between the ceramic and the electrode. The metalized wafers are then inspected and the attributes documented. Precise controls during the electrode process ensures that the components produced from the wafers will have exceptional long-term reliability.

Dice

The electroded thermistor wafers are diced into small chips using high speed semiconductor dicing saws. The saws use diamond blades and are capable of producing high quantities of extremely uniform die. The resulting thermistor chips can be as small as 0.010" square to over 1.000" square. The variance in chip size throughout a group of diced thermistor chips is virtually immeasurable. A typical thermistor wafer can yield thousands of thermistor chips. After dicing, the chips are cleaned and inspected for dimensional and electrical characteristics. The electrical inspection includes verification of nominal resistance value, resistance-temperature characteristics, production yield and the determination of lot acceptability for the particular application. Resistance and resistance-temperature characteristics are measured using precision temperature baths controlled to within as precise as 0.001° Celsius. All test equipment of AMPFORT, is calibrated on a regular basis and is traceable to N.I.S.T. In addition, Littelfuse maintains primary temperature and resistance standards.

Resistance Test

All thermistors are tested for proper resistance value, usually 25°C. The chips are normally tested automatically, but can also be tested manually depending upon the quantity produced and specification. The automatic chip handlers are interfaced with resistance test equipment and computers which are programmed by the operator to place the chips into various bins dependent upon their resistance value. Each automatic chip handler is capable of testing up to 9,000 parts per hour with exceptional accuracy. In addition to the chip sorters, Littelfuse has several automatic leaded component handlers which are capable of sorting the finished thermistors into up to eleven bins. The automatic sorters result in increased product quality as well as reduced lead time and lower costs.

Lead Wire Attachment

In some cases the thermistors are sold in chip form and do not require lead wires, however in most cases, lead wires are required. The thermistor chips are attached to lead wires by either soldering or by pressure contact in a diode style package. In the soldering process, the thermistor chips are loaded on lead frames which rely upon the spring tension of the wires to hold the chip during the soldering process. The assembly is then dipped into a molten solder pot and removed. Dipping speeds and dwell times are precisely controlled in order to avoid subjecting the thermistor to excessive thermal shock. Special fluxing agents are used as well to enhance soldering performance without harming the thermistor chip. The solder adheres to the chip electrode and to the lead wire, thereby, providing a strong bond of the wire to the chip. For the diode style "DO-35" packaged thermistors, the thermistor chip is held between two lead wires in an axial fashion. A glass sleeve is placed around the assembly and the assembly is heated to an elevated temperature where the glass sleeve melts around the thermistor chip and seals to the lead wires. As in diode construction, the pressure that the glass exerts on the assembly provides the necessary contact between the lead wires and the thermistor chip.
The lead wires used on thermistors are typically copper, nickel, or an alloy and are generally tin or solder coated. Low thermally conductive alloy lead wire material may be used in certain applications which require the thermistor to be thermally isolated from the lead wire. In most applications, this allows the thermistor to respond more rapidly to changes in temperature. After attachment, the bond between the lead wire and chip is inspected. A strong solder interface helps guarantee the long-term reliability of the completed thermistor.

Encapsulation

In order to protect the thermistor from the operating atmosphere, humidity, chemical attack, and contact corrosion, the leaded thermistor is often coated with a protective conformal coating. The encapsulant is typically a high thermally conductive epoxy resin. Other encapsulants include silicone, ceramic cement, lacquer, urethane, and shrink sleeving. The encapsulant also assists in assuring good mechanical integrity of the device. Thermal response of the thermistor is taken into consideration when choosing an encapsulating material. In applications where fast thermal response is essential, a thin coat of a high thermally conductive encapsulant is utilized. Where environmental protection is more important, another encapsulant may be chosen. Encapsulants such as epoxy, silicone, ceramic cement, lacquer, and urethane are normally applied using a dip process and the material is either allowed to cure at room temperature or placed in an oven at an elevated temperature. Precise time, temperature, and viscosity controls are used throughout the process in order to ensure that pinholes or other deformities do not develop.

Termination

Thermistors are frequently supplied with terminals attached to the ends of its lead wires. Before the terminals are applied, the insulation on the lead wires is stripped appropriately to accommodate the specified terminal. These terminals are attached to the lead wires using specially tooled application machines. Subsequently, the terminals may be inserted into plastic or metal housings before being shipped to the customer.

Probe Assembly

For environmental protection or for mechanical purposes, thermistors are often potted into probe housings. These housing can be made of materials including epoxy, vinyl, stainless steel, aluminum, brass, and plastic. In addition to providing a suitable mechanical mounting for the thermistor element, the housing protects it from the environment to which it will be subjected. The proper selection of lead wire, lead wire insulation material, and potting material will result in a satisfactory seal between the thermistor and the outside environment.

Marking

The completed thermistor can be marked for easy identification. This can be as simple as a color dot or more complex such as a date code and part number. In certain applications, the coating material on a thermistor body may have dye added in order to obtain a specified color. A color dot is typically added to a thermistor body utilizing a dipping process. Marking that requires alphanumeric characters is produced with a marking machine. This machine simply marks the part with a permanent ink. The ink is cured at an elevated temperature.

Final Inspection

All completed orders are inspected for physical and electrical defects on a "Zero Defect basis". All parameters are inspected and documented prior to shipment of product.

Pack And Ship

All thermistors and assemblies are carefully packaged and tagged with a bar code label containing, as a minimum, the following information:
Part number
Customer's part number
Customer's purchase order number
Date of shipment
Quantity

The R&D organization of Ampfort Electronics is a high-level research and development platform for NTC thermal ceramic materials in China and the exchange of domestic talents with greater influence Cooperative scientific research base. The research center conducts extensive analysis and research on NTC thermistor ceramic materials, innovative research on new NTC thermistor products, new processes, and new equipment, large-scale NTC thermistor research, industrial production technology research, and the development of related scientific and technological achievements into productivity Strategic research, etc. The research center covers an area of 1,700 square meters, with more than 50 sets of various test and analysis equipment and instruments. For the continuous improvement of product technology, continuous update of technology, continuous improvement of performance and quality, it provides strong support and reliable guarantee.

AMPFORT R&D team carries forward the spirit of tenacious hard work and hard work, and has successively developed a large number of new products, new processes, new tooling, and new equipment. Technicians have won many times the government-issued scientific and technological progress awards, participated in many national and provincial scientific and technological projects, and published many papers in specialized technical journals at home and abroad. They not only have a solid professional academic theoretical foundation, but also have rich practical experience in the development of semiconductor sensitive components and related fields for a long time. 

They are the real team.

They promised and borne together. They share information, opinions and ideas together, and make joint decisions to help each member work better. They not only focus on personal goals, but also pay attention to the value-added effects of multiple members working together.

They contribute together. Together, they revolve around a goal that every member can believe in. They challenge together, collaborate with each other, and share the results of their work on an equal footing.

They are passionate, energetic, ambitious and ambitious

AMPFORT people are a group of people who have ideas, want to develop, and have the courage to practice.

They are passionate, but they have a rich heritage; they have unlimited vitality, and they can also endure loneliness; they have ideals, not fantasy; they are ambitious, but not impetuous; they have unlimited ideas and reject mediocrity.

They are happy

Here, they complement each other's strengths and don’t have to worry about the implementation of their ideas being limited to their own capabilities; here, each of their ideas will get the team’s pertinent opinions and eventually become perfect; here, they are together, there is no high and low, Only confidants are with them; here, their work is well-deserved affirmation, and there will be rewards for their efforts...

Here they are living!

So, why not be happy?