In recent years, China's home appliance market has become more high-end, and air-cooled design and refrigerators designed for door opening are favored by consumers. The unique Hybrid hybrid defrosting patent design of Oprah refrigerator is far away from defrosting; its door opening and 360° rotating shelf design is full of fashion and humanity; its preservation and energy saving function is a competent housekeeper of gourmets. Pursuing a fresh, quality life, the Oprah refrigerator is the best choice.
Oprah Refrigerator is a high-end product of Hefei Jinghong Electric Appliance Co., Ltd. is a modern professional refrigerator manufacturer. It relies on the strong economic strength of the headquarters and is committed to the design, manufacture and sales of high-end refrigerators. The R&D team has reached the leading level in the industry. Oprah refrigerators, whether from its craftsmanship or from the functional features of the products, are in line with current consumer demand and are the must-have brands for consumers to pursue fashion.
Air-cooled, frost-free and moisturizing
The frost-free refrigerators currently recommended in the market generally adopt air-cooled design. The refrigerator adopts the ordinary air-cooling circulation system, the evaporator is placed at the bottom of the refrigerator, the cold air is blown from the freezing chamber to the refrigerating chamber, and the cold air passes through the two compartments. Conveying, taking away a lot of water, the humidity is only 20-30%, the food has no moisture, the taste will naturally deteriorate. The Oprah refrigerator uses a unique Hybrid hybrid defrosting patent design to effectively reduce the cycle of frost formation. The defrosting interval is twice that of an ordinary refrigerator, and the chance of water loss from fruits and vegetables is reduced by 50%. At the same time, the Oprah refrigerator has a special temperature sensor for fruits and vegetables, which is used to adjust the cold air to make it circulate and evenly moisturize. It also adds a protective measure for the moisturizing of fruits and vegetables to keep the fruits and vegetables fresh for a long time.
The first secret of preservation: instant freezing
Oprah refrigerators also have a pioneering secret: fresh frozen. Instant freezing refers to the instant freezing of food at -7 °C to protect food cell tissue and original nutrients into a unique technology that is not destroyed. Ordinary freezing allows ice crystals to penetrate from the periphery of the food to the inside, forming needle-like crystals inside, destroying food cells and affecting food taste and nutrients. Instant freezing can make ice crystal grains evenly penetrate into food cells, protect food cells from damage, and the frozen food can still maintain the taste and nutrition after cooking.
In addition to protecting food nutrition and inhibiting frostbite, instant freezing allows for a one-size-fits-all function. The fresh meat we just bought from the vegetable market may not be easy to cut. When the meat is frozen in the freezer, it can be cut very easily, without thawing, or even cut into thin slices. In the state of instant freezing, the food can achieve -7 ° C without freezing, but the particles are frozen instantaneously. This technology can maintain the moisture and taste of the food, protect the cell tissue of the food, and the freezing of the ordinary refrigerator makes the food knot. Ice, during the thawing process, the cells in the meat are destroyed, and the gravy of the fresh meat is lost as the thawing process. Some refrigerators have a "zero degree preservation" function, the meat is frozen at 0 °C, so that the meat is not too hard, although it can also be achieved across the board, but only for two or three days, the preservation time is short, and the Oprah refrigerator instant The freezing function is frozen at -7 ° C. The meat is kept fresh for a longer period of time and can be stored for 2 weeks, and the nutrition and color of the meat are unchanged.
Hot food preservation is also one of the functional points of instant freezing. Oprah's instantaneous freezer can also freeze the hot food below 80 °C, just make or leave the leftover food. If it is still hot, it will consume electricity or damage the refrigerator in the ordinary refrigerator. Oprah is You can easily solve the problem. The hot food can be directly put into the switching room without cooling. The instant freezing function will freeze the hot food, let the ice crystal grains spread in all corners of the food, evenly cool the hot food, and keep the moisture of the food before freezing. And fresh taste.
What PCB designer Must Know About Impedance Control PCB
Controlled Impedance PCB Meaning
Impedance control has been one of the essential concerns and tough problems in high-speed PCB design. Impedance is the sum of the resistance and reactance of an electrical circuit. The resistance being the opposition to current flow present in all materials. In high frequency applications, controlled impedance helps us ensure that signals are not degraded as they route around a PCB. Resistance and reactance of an electrical circuit have a major impact on functionality, as certain processes must be completed before others to ensure proper operation.
Because of complex processors, USB devices and antennas are printed directly on the circuit board surface. The speed of signal switching on the circuit board increases, and the electrical characteristics of the tracks that transmit signals between devices become more and more important. Therefore, more and more PCB designs need impedance control and testing.
Impedance control technologies are quite important in high-speed digital circuit design in which effective methods must be adopted to ensure the excellent performance of high-speed PCB. The impedance of a PCB is largely determined by some factors, such as trace width, copper thickness, dielectric thickness, dielectric constant. Impedance, generally measured in Ohms. We must control the resistance and reactance of an electrical circuit to ensure the quality of signal in the complex design. For example single-ended impedance 50 ohm ±10%, differential impedance 100ohm ±10%.
When to Use Controlled Impedance
When a signal must have a particular impedance in order to function properly, controlled impedance should be used. In high frequency applications matching the impedance of PCB traces is important in maintaining data integrity and signal clarity. If the impedance of the PCB trace connecting two components does not match the components` characteristic impedance, there may be increased switching times within the device or the circuit. There may also be random errors.
Please note that we also need special instructions here:In DC circuits there is no reactance and the resistance of copper conductors is typically insignificant. However in high speed AC circuits (those with sharp changes in voltage and/or current) the reactance and thus the impedance can become very significant. This can become critical to a design's functionality because of the effects that changes in the impedance along the signals path from transmitter to receiver will have on the efficiency of power transfer as well as signal integrity. While a circuit`s speed is often expressed as the frequency of the wave form: the critical concern is the speed at which the voltage and/or current is required to change.
What Determines Controlled Impedance?
The characteristic impedance of a PCB trace is typically determined by its inductive and capacitive reactance, resistance, and conductance. These factors are a function of the physical dimensions of the trace, the dielectric constant of the PCB substrate material, and dielectric thickness. Typically PCB trace impedance can range from 25 to 125 ohms. The impedance value generated from the PCB structure will be determined by the following factors:
– Width and thickness of the copper signal trace (top and bottom)
– Thickness of the core or prepreg material on either side of the copper trace
– Dielectric constant of the core and prepreg material
– Distance from other copper features
Impedance Control In PCB Design
Electrical Impedance: A measure of opposition to time-varying electric current in an electric circuit.
The Problem: "A", "B" and "C" signals all reach the component at the same time.
The Solution: Apply Impedance to Circuit "C" to slow the signal enough for the component to first calculate ("A"+B").
Similar with a cable, the signal encounters a change of impedance arising from a change in material or geometry. Part of the signal will be reflected and part transmitted. These reflections are likely to cause aberrations on the signal which may degrade circuit performance (e.g. low gain, noise and random errors). In practice, board designers will specify impedance values and tolerances for board traces and rely on the PCB manufacturer to conform to the specification.
When rise times continue to reduce, inevitability the number of traces requiring impedance control will continue to increase. Where impedance control is needed it is important to control it accurately, calculating it with the most representative cross-section we can create.
Applications of Controlled Impedance
Controlled Impedance should be considered for PCBs used in fast digital applications such as:
– Telecommunications
– Computing 100MHz and above
– High Quality Analog Video
– Signal Processing
– RF Communication
Impedance Control PCB Manufacturing
In order to meet the growing demand of impedance control PCB, PCB manufacturers have invested a lot of money and manpower and material resources in production technology, in order to meet the production requirements of customers.
Due to the difficulty of impedance control PCB production, PCB manufacturers generally require PCB designers or purchasers to provide more detailed information and requirements, such as the type of material required, copper weight and thickness of the board, the number of layers, gerber file, so that the manufacturer can prepare the bill of materials (BOM). Impedance information should be clearly marked in Gerber file. If the necessary information is lacking, even a little key information will make it difficult or impossible for the manufacturer's engineers to know exactly what the customer needs.
Impedance-controlled PCBs are also divided into three different situations:
No Impedance Control: This is a situation where you do not need any extra design elements to ensure correct impedance because you have very loose impedance tolerance. Naturally, this will result in a faster-completed, less expensive board because the manufacturer does not have to include any special measures.
Impedance Watching: What is impedance watching? This is a situation where the designer will outline the impedance control trace and the PCB provider adjusts the trace width and dielectric height accordingly. Once the manufacturer approves these specifications, they can begin to manufacture the board. You can request a Time Domain Reflectometry (TDR) test to confirm the impedance for a fee.
Impedance Control: Actual impedance control is something you will typically only request when your design has tight impedance tolerances that could be tough to hit the first time around. When the capability limits of the manufacturer get close to the dimension requirements, it can be tough to ensure target impedance on the initial attempt.
In the case of impedance control, the manufacturer makes the circuit board achieve the target impedance as far as possible. Then they tested TDR to see if they succeeded. If not, they adjust accordingly and try again until they reach the required impedance.
Impedance Control PCB Fabricator
Impedance Control PCB is too complicated? No worry! JHY PCB engineers can help you at any time as we have three shifts. Free stack-up and impedance calculations can be offered upon request. We will work with your engineering team at the conceptual level of the PCB design to assist you to get better results in controlling impedance by choosing the suitable laminate and layer stack up.
Why Impedance Control PCB can be shipped timely all the time? As common materials are stored well in JHY PCB warehouse regularly. We have heavy copper thickness, 2oz, 3oz or more. Odd copper thickness H/1 oz, H/2 oz, 1/2 oz. Foil: 1/4 oz, H oz, 1 oz, 2 oz, 3 oz.
If you need order Impedance Control PCB, just make notes in Readme file, and send it together with Gerber, our engineer will take care of it. Have a try!
Impedance Control PCB
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