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  • Conventional PCB Board Inspection Standards

    What is the PCBA board inspection standard?

    Let’s take a look at the standard shortcomings of quality testing..

    1. Serious shortcomings(expressed in CR): Were enough to the human body or machine damage or endanger the failures of life safety, such as security does not match/burn …
    gesptechnologypcbJuly 6, 2017 Blog 0 Comment433views
  • The What, the Whys, and the Hows of SMT Stencils for Prototype PCBs

    There are plenty of different kinds of circuit boards, but in general, there are three major types of printed PCB fabrication: single-sided, double-sided, and multi-layered. However, no matter the …

    gesptechnologypcbJune 16, 2017 Blog 0 Comment399views
  • Make Sure to Consider These Factors When Creating a PCB Layout

    In a world that is dependent on technology, it is only natural that the world of circuit board prototyping becomes more and more complex. This especially goes for

  • How to Control EMI Radiation with PCB Layered Stackup

    Introduction

    There are a variety of solutions available for EMI issues. Modern techniques for EMI suppression include applying EMI suppression coatings. choosing components that are suited for EMI suppression, and designing for EMI simulation. This article begins with the most EMI radiation with PCB layered stackup. and continues on to discuss the role that PCB layered stackup plays in the control of EMI radiation. as well as the design skills required to create such a stackup.

    What Exactly is EMI?

    Electromagnetic interference, abbreviated as EMI. refers to electromagnetic waves and electronic components. that play a part in the interference phenomenon. There are two types of interference: conducted interference and radiation interference. Conducted interference is the signal coupling. between two electrical networks via a conductive medium. In high-speed PCB and system design, high-frequency signal lines. integrated circuit pins, all types of connectors. and so on can become a source of radiation interference with antenna characteristics. emit electromagnetic waves, and interfere with the normal operation. of other systems or subsystems within the system.

    Control EMI Radiation with PCB Layered Stackup

    Control EMI Radiation with PCB Layered Stackup

    What Difficulties Might EMI Cause?

    As wireless communication device technology such as “5G” advances. manufacturing sites such as factories and society continue to push IoT. and electronic control mechanisms such as car electrification become more diversified and complicated.

    Electromagnetic waves of various frequencies are propagated during the miniaturization. and high functionality of electrical/electronic equipment. and electromagnetic waves become noise. causing communication barriers and equipment malfunctioning. which not only prevents the original capabilities . but also poses the risk of causing major accidents. As a result, EMI countermeasures are critical for preventing . the propagation of electromagnetic noise.

    How to Control EMI Radiation with PCB Layered Stackup?

    Let me tell you something!

    There are numerous approaches to addressing the EMI issue. Modern EMI suppression approaches include the use of EMI suppression coating. the selection of appropriate EMI suppression components, and the design of an EMI simulation. In this article, GESP PCB discuss about explores the significance of PCB stacking in limiting EMI radiation.How to Control EMI Radiation with PCB Layered Stackup? and PCB design suggestions based on the most fundamental PCB layout.

    Power Bus to Factors Control EMI Radiation with PCB Layered Stackup

    In the IC power supply pin near the appropriate placement of the proper capacity of the capacitor. IC output voltage can jump faster. However, the problem is not so far. Since the capacitor has a characteristic of a limited frequency response.

    This makes it impossible to generate the harmonic power. that required to drive the IC output in a full frequency band. Also, the transient voltage formed on the power supply bus. creates a voltage drop across the inductor at both ends of the decoupling path. These transient voltages are the primary standard mode of EMI sources. How should we solve these problems?

    For the ICs on our circuit boards, We can see the power supply layer around the IC. as a first high-frequency capacitor that collects the amount of energy . that is leaking from discrete capacitors that provide high-frequency energy for clean output. Also, the excellent power supply layer inductance is small. so the inductance of the synthesis of the transient signal is too tiny. thereby reducing the standard mode EMI.

    EMI RADIATION

    EMI RADIATION

    Of course, the connection between the power supply layer . and the IC power supply pin must be as short as possible. because the rising edge of the digital signal is faster and faster. and it is best to connect directly to the pad where locate the IC power supply pin.

    To control the standard mode EMI, the power plane will help decouple . and have a sufficiently low inductance. which must be a well-designed power layer pairing. Some people may ask, to what extent is it useful? The answer to the problem depends on the stratification of the power supply.

    Material Factors Control EMI Radiation with PCB Layered Stackup

    The material between the layers, and the operating frequency (i.e., the function of IC rise time). Typically, the spacing of the power supply is six mils, and the interlayer is FR4 material. the equivalent capacitance per square inch of the power supply layer is about 75pF. The smaller the interlayer spacing, the larger the capacitance.

    There are not many devices with a rise time of 100 to 300 ps. but devices with high rise times in the range of 100 to 300ps will have a high percentage according to the current IC development speed. For circuits with a rise time of 100 to 300 ps, the three mil layer spacing will no longer apply to most applications.

    At that time, it is necessary to use layer spacing of less than 1mil layered technology. and with a high dielectric constant material instead of FR4 dielectric material. Now, ceramic and pottery plastic can meet the design requirements of the 100 to 300ps rise time circuit.

    Although new materials and new methods used in the future. for today’s standard 1 to 3 ns rise time circuits. the 3 to 6 mil layer spacing and FR4 dielectric material are usually sufficient to handle high-end harmonics . and make the transient signal low enough, Common mode EMI can drop very low. The PCB stacking design example presented in this paper will assume a layer spacing of 3 to 6 mils.

    Electromagnetic Shielding

    From the signal alignment, a good stratification strategy should put all the signal lines on a layer or layers. these layers next to the power layer or ground plane. For power, a good stratification strategy should be the power layer . and the ground layer adjacent to the power layer and the ground layer as small as possible. which is what we talk about the “layered” strategy.

    PCB Stacking

    What kind of stacking strategy helps to shield and suppress EMI? The following layered stacking scheme assumes . that the supply current flows on a single layer . and that a single voltage or multiple voltages distributed across different parts of the same layer.

     4 Layers

    There are several potential problems with 4-layer board design. First, the traditional thickness of 62mil four-layer board. even if the signal layer in the outer layer. power and ground layer in the inner layer. the power supply layer and the ground layer spacing is still too large.

    If the cost requirement need to consider the following two traditional 4-layer alternatives. Both of these solutions improve EMI suppression performance. but only for applications where the board component density is low enough. and there is sufficient area around the component (placing the required power cladding layer).

    The first is the preferred solution, the outer layers of the PCB are strata. and the middle two are signal/power layers. The power supply on the signal layer routed with a wide line. which makes the path impedance of the supply current low. and the impedance of the signal microstrip path is low.

    4-layer PCB Structure

    From the EMI control point of view, this is the best existing 4-layer PCB structure. The second program of the outer layer of power and ground, the middle two layers of the signal. The solution is less important than the traditional 4-layer board. and the interlayer impedance is as bad as the traditional 4-layer board.

    If you want to control the trace impedance, the stacking solution should be carefully placed in the power supply. and ground bridge below the copper island. In addition, the copper or the copper on the power source or formation need to interconnected. as much as possible to ensure DC and low-frequency connectivity.

    6 Layers

    If the component density on the 4-layer PCB board is relatively large. it is preferable to use a 6-layer circuit board. However, some of the stacking schemes in the 6-layer PCB board design. that are not good enough for the shielding of the electromagnetic field. which has little effect on the reduction of the transient signal of the power supply bus.

    The first example of the power and ground placed on the 2nd and 5th. due to the power supply copper resistance is high. the control of common mode EMI radiation is very negative. However, from the signal impedance control point of view, this method is correct.

    The second example places the power supply and ground on the 3rd and 4th layers. and this design solves the problem of the copper cladding of the power supply. Since the electromagnetic shielding performance of the first and sixth layers is poor. the differential mode EMI increases. This design solves the differential mode EMI problem if the number of signal lines on both outer layers is the least . and the trace length is very short (less than 1/20 of the highest harmonic wavelength of the signal).

    The suppression of the differential mode EMI is particularly good by filling the non-element. and non-traces of the outer layer with copper . grounding the copper area (at every 1/20 wavelength interval). As mentioned earlier, the copper area connected to the internal ground plane.

    6-Layer Board Control EMI Radiation with PCB Layered Stackup

    General high-performance 6-layer board design the first and sixth layer of cloth for the formation. the third and fourth floor to take power and ground. Since the dual layer centered of the microstrip signal line . between the power supply layer and the ground layer. the EMI suppression capability is excellent.

    The drawback of this design is that there are only two layers of the wiring layer. As mentioned earlier, if the outer traces are short and copper routed in the non-traced area. the same stack achieved with a conventional 6-layer board.

    6-layer PCB Structure

    Another 6-layer board layout for the signal, ground, signal, power. which can achieve advanced signal integrity design required environment. The signal layer is adjacent to the ground plane, and the power supply layer and the ground plane are paired. The downside is that the layers of the stack unbalanced.

    This usually causes trouble in PCB manufacturing. The solution to the problem is to fill all the blank areas of the third layer of copper. fill copper if the third layer of copper density close to the power layer or ground layer. the board can not be strictly counted as a structural balance of the circuit board. The copper-filled area connected to the power supply or grounded. The distance between the connecting vias is still 1/20 wavelength. not necessarily connected everywhere.

    10 Layers 

    Since the insulation isolation layer between the multilayer boards is very thin. the impedance between the circuit board layers of the 10 or 12 layers is very low. and excellent signal integrity expected to achieved as long as . there is no problem with delamination and stacking. According to the thickness of 62mil manufacturing 12-layer board. the more difficult to be able to process 12-layer board manufacturers are not many.

    Since there is always an insulating layer between the signal layer and the circuit layer. it is not optimal to allocate the middle 6-layer signal line in the 10-layer board design. In addition, it is important that the signal layer and the circuit layer are adjacent. that is, the board layout is signal, ground, signal, signal, power, ground, signal, signal, ground, signal.

    This design provides a good path for the signal current and its loop current. The proper routing strategy is that the first layer traced along the X direction. the third layer traced along the Y direction, the fourth layer traced along the X direction, and so on.

    10 Layers Factors Control EMI Radiation with PCB Layered Stackup

    Intuitive to see the line, the first layer one and the third layer is a pair of hierarchical combination. the fourth and seventh layer is a pair of layered combination. 8th and 10th layer is the last pair of layered combination. When the direction of the alignment needs to changed, the signal lines on layer changed by “via” to layer 3. In fact, it may not always be done, but as a design concept or to try to comply.

    Similarly, when the signal alignment direction changes. it should be through the hole from the 8th and 10th layers or from the 4th to 7th floor. This wiring ensures that the coupling between the forward path and the loop of the signal is tightest.

    10-Layer PCB Structure

    For example, if the message routed on layer one and the circle is on layer 2. Only on layer 2, the sign on sheet one transferred to layer three even by “vias” . The circuit is still on the second floor, thus maintaining low inductance. broad capacitance characteristics, and excellent electromagnetic shielding performance.

    If the actual alignment is not the case, how do? Such as the first layer of the signal line through the hole to the 10th layer. then the loop signal had to find from the 9th-floor ground plane. loop current to find the nearest ground vias. such as resistors or capacitors and other components of the ground pin. The If you happen to have such a hole in the vicinity, it is fortunate. If there are no such vias available, the inductance will become more abundant. and the capacitance will be reduced, EMI will increase.

    When the signal line must pass through the hole from the current pair of wiring layer to the other wiring layer. placed near the hole in the ground through the hole. so that the circuit signal can be successfully returned to the appropriate ground plane. For Layer 4 and Layer 7 hierarchical combinations. the signal loop will return from the power plane or ground plane. because of the capacitive coupling between the power supply layer. and the ground plane is excellent and the signal is easy to transmit.

    Multi-power Layer Design

    If the two power supply layers of the same voltage source need to output high current. the circuit board fabricated into two power supply layers and ground planes. In this case, an insulating layer placed between each pair of the power supply layer and the ground layer. This gives us the desired equalization of the current of two pairs of impedance equal to the power bus. If the stacking of the power supply layer causes the impedance to be unequal. the shunt is not uniform, the transient voltage will be much larger. and the EMI will increase dramatically.

    If there are multiple values of different supply voltages on the board. numerous power planes required accordingly. keeping in mind the separate power supply layers and ground layers for various power sources. In both cases, make sure that the pairing power supply layer . and the ground plane are at the location of the circuit board. bearing in mind the manufacturer’s requirements for the balanced structure.

    To Sum Up

    The discussion of circuit board delamination and stacking is limited to the fact. that most engineers design circuit boards with a conventional printed circuit board . with a thickness of 62 mils without blind holes or buried vias. Thickness difference is too vast for the circuit board. and the proposed stratification scheme may not be ideal. Also, the blind hole or hidden hole. circuit board processing process is different from the stratification method is not applicable.

    The thickness of the circuit board design, via the process and the number of layers of the circuit board. is not the key to solve the problem. The great layered stack is to ensure the bypass and decoupling of the power supply bus . so that the transient voltage on the power supply layer or ground layer is the smallest .

    Conclusion

    And the signal and power of the electromagnetic field shielding the key. Ideally, there should be an insulation barrier between the signal trace layer and its return ground layer. and the paired layer spacing (or one or more) should be as small as possible. According to these basic concepts and principles. it designed to meet the design requirements of the circuit board. Now, IC’s rise time is short and will be shorter. the technology discussed in this paper to solve the problem of EMI shielding is essential.

    gesptechnologypcbJune 1, 2017 Blog 0 Comment389views
  • How to Design a PCB Layout: Everything You Need to Know

    Today’s electronic technology permeates our lives everywhere. For example, cell phones, computers, TVs, cars or airplanes, 5G communication. For all kinds of electronic products, PCB layout is an important design process. that must be carried out to transform them from electrical schematics to a concrete product. Fixer the electronic components in specific locations in the device or the terminals of the components . are reliably connected in an organized manner. The soundness of the design is closely related to the production and quality of the product. and without a correct PCB layout, most devices will not function.

    And for many people just engaged in electronic design. although they have learned the printed circuit board design software. but the design of the printed circuit board often encountered: the selection of unusable components. footprint does not match, wiring confusion. How to correctly layout the PCB for smooth production, let us go through this article in detail to understand.

    • What is PCB Layout?
    • The basic principles of PCB Layout
    • Placement order
    • PCB layout techniques
    • PCB layout considerations
    • Layout check
    • PCB layout software
    • GESP PCB layout service advantages

    What is the PCB Layout?

    PCB layout is a broad term that refers to several processes required to design a PCB. It includes creating alignments, mounting hole cutouts. marking and specifying component locations. PCB layout divided into two ways: manually or automatically. Almost all PCB design software has an automatic routing feature. Many designers use the automatic routing feature.

    because it saves time and makes the process easier. Although the auto-routing feature of PCB design is the easier route, it is not always the best. This is because it is not always as precise and symmetrical as it should be. To ensure that automatic routing produces the best results. you need to use the proper parameters . as they enable the automatic function to calculate the routing correctly.

    Layout Check

    Layout Check

    Basic Principles of PCB Layout

    • Be clear about the needs of the producer
    • Manage the spacing of the original parts in the layout
    • Always create a ground plane
    • Avoid overlap

    Be clear About the Producer’s Needs

    Know what the producer needs Before you start placing components. you need to consult with your manufacturer. It is important to be clear about their requirements, such as how many layers they can handle. Other requirements may include things like minimum alignment width and alignment spacing.
     

    Managing The Spacing of Originals in a Layout

     

    Managing the spacing of originals in a layout When current flows through copper traces. Temperature increase. This heat Lowering the temperature. so that it does not exceed the safety threshold. You can control this heat by managing the width of the markers. and ensuring that there is enough space between them. a process called PCB alignment spacing. Wire spacing can be a challenge when dealing with high-density interconnect PBCs. To determine what needs to be done about line spacing in this case. it is critical to understand some important parameters. However, this can be tedious and time consuming. The good news is that most PCB design software based on the important parameters to design.

    Always Create a Ground Plane

    It is always important to have a common ground terminal in the circuit schematic. This is critical for PCB layouts because it provides traces with the same reference point to measure voltages. Problems arise when you try to wire using a trace rather than a ground plane. Cadence.com, a provider of software, hardware, and IP. identifies three key roles for the grounding layer in PCB design. Voltage return:components in the PCB connected to the power network, . and the grounding network provides a path for returning voltages. Signal return: Provides a path for returning signals so that they do not interfere too much. Noise and interference reduction. The large conductive area of the ground plane helps reduce interference. because it has a lower impedance than when using an alignment wiring ground network.

    Considerations of PCB Layout

    Considerations of PCB Layout

    Avoid Overlap

    One of the challenges of mixed-signal PCB layouts is overlapping planes. A mixed-signal PCB layout has both digital and analog circuits on one board. If not managed properly, this overlap can introduce interference problems . between digital and analog signals. Therefore, when it comes to PCB layout, you need to make sure you avoid overlap-related problems at all costs. GESP recommends that you “always leave space between components”.

    Placement Order

    1.Placement of components that have a close fit with the structure, such as power sockets, indicators, switches, connectors, etc.
     
    2.Placement of special components, such as large components. heavy components, heat generating components, transformers, ICs, etc.
     
    3.Placement of small components.

    PCB Layout Skills

    1.Important unit circuit, core components limited layout
     
    2.Evenly distributed, properly adjusted
     
    3.small components around the large components can not placed. debugging components around the adequate space
     
    4.the same part of the circuit, try to use symmetrical layout
     
    5.high voltage, high current signals and small current, separated low voltage weak signals. separate Analog signals and digital signals . separate high-frequency signals and interference signals . high-frequency components are spaced adequately.
     
    6.The key signal lines priority, power, analog signals, high-speed signals. clock signals and differential signals priority wiring.
     
    7.Start wiring from the single board connection line relationship of the most complex devices. and start wiring from the most dense area of the single board connection line.

    GESP PCB Layout Service

    GESP PCB Layout Service

    Considerations of PCB Layout

    1 Power, Ground Handling

    Even if the wiring in the entire very well. but due to power, ground considerations are not thoughtful interference. caused by the performance of the product will decline. and sometimes even affect the success rate of the product. So the electricity, ground seriously wiring. the electricity, ground noise generated by the interference to a minimum, to ensure product quality.
     
    For each engineer engaged in the design of electronic products are aware of the noise . between the line and the power supply of the reasons. only to reduce the type of suppression noise to express:
     
    It is well known to add a decoupling capacitor between the power supply and the ground.
     
    As far as possible to widen the power, ground width. preferably ground than the power line width, their relationship such as. ground> power line> signal line, usually, signal line width: 0.2 ~ 0.3mm, Fine width of up to 0.05 ~ 0.07mm, the power line is 1.2 ~ 2.5mm
     
    The PCB of the digital circuit can use a wide wire to form a loop. that is, to form a ground to use with a large area of copper for the ground line. in the printed circuit board has not been used on the ground connected with the ground as a ground. Or made of multi-layer board, power, ground each occupied a layer.

    2 Digital Circuit and Analogue Circuit Common Ground Processing

    Now there are many PCB is no longer a single functional circuit . but by the digital circuit and analogue circuit mix. So when wiring needs to consider the interference between them. especially on the ground noise interference.
     
    Digital circuit frequency is high, the sensitivity of the analog circuit is strong, the signal line, the high-frequency signal line as far as possible away from the sensitive analog circuit devices, the ground, the whole PCB on the outside world only one node, so Must be handled within the PCB number, the problem of the common ground, and in the board of digital and analog ground is actually separated from each other between them are not connected, but in the PCB and the external interface (such as plugs, etc.). Digital and analogue to a little short, please note that there is only one connection point. There are also on the PCB on the ground, which determined by the system design.

    3 Signal Lines on the Electric (ground) Layer

    In the multi-layer printed circuit board wiring. because the signal line layer is not finished cloth line left is not much. and then add more layers will cause waste will also increase the production of a certain amount of work. the cost has increased accordingly To solve this contradiction. you can consider wiring in the electrical (ground) layer. First consider the power layer, followed by the formation. Because it is best to preserve the integrity of the formation.

    4 Large Area Conductor in the Treatment of Connecting Legs

    In a large area of the ground (electricity), the commonly used components of the legs . connected to the connection legs to deal with the need for comprehensive consideration. the electrical performance, the component legs of the pad and copper surface is better. but the Components of the welding assembly. there are some bad risks such as welding need high-power heater. Or easy to cause virtual solder joints.
    So taking into account the electrical performance and process needs. made of cross-pad, known as the heat shield.commonly known as the thermal pad . so that the welding can be too much heat due to cross-section of the potential Greatly reduced. Multilayer board of the power (ground) layer of the same treatment.

    5 Cabling in The Role of Network System

    In many CAD systems, cabling determined by the network system. Grid is too dense, although the channel has increased. the pace is too small, the figure of the amount of data is too large. which must have a higher storage requirement of the equipment. but also the object of computer electronic products operating speed Great influence. And some passages are ineffective, such as those occupied by the pads of the component legs or by the holes. The grid is too sparse, the passage of too little impact on the cloth rate. So there must be a dense and reasonable grid system to support the wiring.
     
    The distance between the legs of the standard component is 0.1 inch (2.54 mm). so the foundation of the grid system is generally set to an integer multiple of 0.1 inches (2.54 mm) or less than 0.1 inches. such as 0.05 inch, 0.025 inches, 0.02 Inch and so on.

    Layout Check

    After the wiring design has completed. the wiring design needs to be carefully checked to see if it conforms to the rules set by the designer. It is also necessary to confirm whether the rules are in line with the requirements of the PCB production process. The general check has the following aspects.
     
    Whether the line and line, line and component pad. line and through-hole, component pad and through-hole. through-hole, through-hole and through-hole are reasonable and meet the production requirements.
     
    Are the power and ground lines the right width, and is the power supply tightly coupled to ground (low impedance)?
     
    Are the best measures taken for critical signal lines. such as the shortest lengths. plus protection lines, and are input and output lines clearly separated.
     
    Are there separate grounds for analog, and digital circuitry sections.
     
    Graphics in the PCB (e.g. icons, markers) can cause signal shorts.
     
    Modifications made to some unsatisfactory lines.
     
    Are there process lines on the PCB? Does the resistor meet the production process requirements. is the resistor soldering size appropriate. and are the character marks pressing the device pads. so as not to affect the quality of electronic devices.
     
    Are the edges of the outer edges of the power supply reduced in multi-layer boards. such as exposed copper foil on the power supply is prone to short circuits.

    PCB Layout Software

    Some of the best PCB layout software on the market include
     
    Autodesk Eagle: comes with a schematic editor for design diagrams, and a PCB layout editor.
     
    KiCad: This is a cross-platform, open source electronic automation suite. It includes a PCB editor for creating professional PCBs. and a schematic editor for editing and creating schematic designs.
     
    Fritzing: has several features including schematics, breadboard layouts, and PCB views.
     
    DesignSpark PCB: Provides an easy-to-learn environment, including schematic capture and PCB layout tools.
     
    EasyEDA: Provides a library designer, PCB editor, and project management tools.
     
    UpVerter: has similar features to EasyEDA. enabling hardware engineers to create, share, and view PCBs and schematics.
     
    ExpressPCB Plus: is EDA software for designing and creating electronic circuits.

    GESP PCB Layout Service

    Even if you can do your own PCB layout, using GESP PCB layout services can bring some advantages. These layout services can be of great help, especially if you are a beginner in this field.
     
    PCB layout services are available for existing and new PCBs. some of the advantages of using PCB layout services include.
     
    Technical competence: We have extensive experience in PCB design when it comes to designing PCBs.
     
    Streamlined process: With PCB layout services, fixed the error early. allowing you to improve your product before marketing.
     
    Better quality: Layout services have better quality . because each service is expected to be better than the competition.
     
    Fast turnaround: With expert services, PCBs can be designed on time with careful planning.
     
    Cheaper: Due to economies of scale, it may be cheaper to use a PCB layout service than to design your own PCBs.

    PCB LAYOUT

    PCB LAYOUT

    Standard PCB Layout Designer Deliverables

    A reliable PCB designer can meet a minimum set of deliverables, including

    Bill of materials (BOM)

    Manufacturing documentation

    PCB layer stacking diagrams

    Complete schematics

    Complete Gerber files

    3D PDF files

    Routing and drilling files

    Conclusion

    PCB layouts are critical for board functionality. Assume you’re having difficulty with your board layout. In that case, you can always seek help from a company that manufactures PCBs according to the best layout plans. Ascertain that the company understands the significance of PCB layouts in order for your boards to function properly.

    gesptechnologypcbMay 31, 2017 Blog 0 Comment400views
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