Ultrasonic knife printed circuit board
What is the meaning of the various layers in the PCB design?
Toplayer - the top layer wiring layer.
Bottomlayer - The underlying wiring layer with traces of electrical characteristics. It is the connection that connects the pins of each component on the board.
Mechanical - The mechanical layer defines the appearance of the entire PCB. In fact, when we say the mechanical layer, it refers to the overall structure of the PCB.
Keepoutlayer - the wiring layer is forbidden, the wiring layer is prohibited to define the boundary of our copper in the electrical characteristics of the cloth, that is, we first define the electrical characteristics of the wiring layer that we have in the future wiring process. It is impossible for the line to exceed the boundary of the prohibited wiring layer.
Topoverlay - the top silkscreen layer.
Bottomoverlay - The underlying silkscreen layer, defining the top and bottom silkscreen characters, is the component number and some characters we generally see on the PCB.
Toppaste - the top layer of the pad.
Bottompaste - The underlying pad layer, the top and bottom pad layers, which refers to the pads of the chip components we can see.
Topsolder - top solder mask.
Bottomsolder - the underlying solder mask, because the PCB board is to be green by default, the place where the two layers are drawn will open a "skylight", not green oil. It can be used in places where large current circulation is required to add additional solder.
The layer of multilaye is actually similar to the mechanical layer. As the name suggests, this layer refers to all layers of the PCB.
A PCB antenna refers to a portion of a PCB for wireless reception and transmission. The antenna is a transducer. When transmitting, it converts the high-frequency current of the transmitter into a space electromagnetic wave; when receiving, it converts the electromagnetic wave intercepted from the space into a high-frequency current and sends it to the receiver. Antenna design is an important part of designing a low-power, short-range wireless transceiver for use in RFID systems.
1. PCB boards and media of different thicknesses must have an effect on the antenna, but the size of the impact will not exceed the range you require.
2. The second point is not very clear.
3, line width, line spacing, copper thickness of the line, dielectric layer thickness, dielectric layer dielectric coefficient, etc. have an impact on the impedance.
Conventionally, the dielectric layer thickness is proportional to the resistance. The copper thickness is inversely proportional to the resistance. The line width is inversely proportional to the resistance. The line spacing between the two lines is proportional to the resistance (the line between the fingers and the impedance line). Distance) is proportional to the thickness of the insulating varnish above the line.
The above is only a rough relationship. If you want to explain it accurately, you should also consider whether the impedance is a single line or a cross, whether it is coplanar or non-coplanar, and so on.
The high frequency PCB design above 2G belongs to the RF circuit design and is not within the scope of high speed digital circuit design discussion. The layout and routing of the RF circuit should be considered together with the schematic, as the layout will cause a distribution effect. Moreover, the RF circuit design of some passive components is realized by parameterized definition, special shape copper foil, so EDA tools are required to provide parametric devices and to edit special shape copper foil.
Mentor's boardstation has dedicated RF design modules to meet these requirements. Moreover, the general RF design requires a special RF circuit analysis tool, the industry's most famous is agilent's eesoft, and Mentor's tools have a good interface.
What issues should I pay attention to when designing a 4-layer PCB?
Distribution of PCB design layers (typically TOP, GND, POWER, BOT).
The ordinary circuit board has no impedance requirements, and the board thickness can be set.
Note that the power ground wire is thickened by 15-30 MIL, the signal line width is 7-15 MIL, and the vias are 12/24 and 20/40.
Pay attention to the trace, the copper pitch, the distance between the device and the trace from the board.
To consider impedance matching, you also need to consider the thickness of each layer of copper and the width of the trace.
Intermediate dielectric thickness and dielectric constant.
The above must be calculated before wiring.
Scanner, look at what board, like a normal motherboard, the resolution is enough to 1200. The scanned image can be BMP or JPG - color, WINDOWS system format.
You can use AUTOCAD to convert a color picture into a monochrome line drawing, then use a ruler to measure the PCB in your hand and put each pad. The coordinates of the four sides of the via and the device are measured, and the size is also measured, and then put into the 99 point. The converted picture has a vague shadow, which can give you a general test effect, so that you don't have to copy too far from the actual one - this is a method, but it is difficult to master, you need to learn a long time. Time, hands can have a feeling.
There is also a method, a software developed by a Shenzhen company called Quickpcb, which can be directly transferred to the color map and then exported to the 99SE.
The way to do this is to open Quickpcb and load the BMP color map you just scanned. Quickpcb is 1:1 to open the color map, so you don't have to measure the coordinates of the pads and vias on the board, and see what is placed directly on the screen. When the board is small, the screen will be enlarged (the computer is good, it is not as clear as the ruler).
The board usually draws the edge of the board first, then places the pads, vias, devices, and then draws the lines, then draws the silk screen, and the device is directly used in the software to make the device. After copying one layer, save it, open another layer of image, and then copy the bottom layer (the order is still pad, via, device, line, silk screen).
The final copy is a file containing two layers of data at the top and bottom, and then open the file with 99SE, you can see, the effect is the same as the direct design.
Strictly implement the ISO9001:2008 quality management system and carry out production according to IPC-A-610E electronic assembly acceptance criteria. The ISO accreditation body strictly reviews the company's PCBA production quality control plan, establishes the production site to meet the standards and implements the quality control plan and measures in accordance with the regulations. The audit includes the production operator's ability, production process and work instructions, equipment compliance requirements, raw material purchase and warehousing, production documents, production site environment and safety assembly, node setup of the production process, etc., forming a complete set of operations. Guide the plan.
A grade A substrate (generally FR-4) is used. Fully automatic copper line and high speed drilling machines ensure high precision and fast delivery during production. All PCB boards pass the open circuit and short circuit of the automatic high-speed flying probe tester for high-voltage insulation and low-resistance conduction test. For high-volume PCB production, professional test racks are used to improve test efficiency.
Stable cooperation in electronic component brands and agents, thick voice, Fenghua, Samsung, Guoju resistors and capacitors; TI, NXP, CJ, Fuji, Fairchild, ST, Qualcomm, Micron, Infineon and other brand IC. Use absolutely original genuine components to ensure quality.
High-speed and high-precision SMT placement machine is the indispensable foundation for PCBA quality control. With high-speed brand placement machine, the maximum precision can reach 0402, which ensures the precision and speed of the patch. The reflow oven in the 10 temperature zone can achieve the best dissolution temperature and solidification temperature of the solder paste, which greatly improves the reliability of the patch and becomes an important part of PCBA quality control. Finally, the appearance of the solder joints is checked using AOI to ensure that the tin is good on each material.
In the design of the PCB board, the anti-ESD design of the PCB can be realized by layering, proper layout and installation. ESD can be well protected by adjusting the PCB layout. * Use multi-layer PCB as much as possible. Compared to double-sided PCB, the ground plane and power plane, as well as the tightly arranged signal line-ground spacing, can reduce the common mode impedance and inductive coupling to achieve a double-sided PCB. /10 to 1/100. It has components for the top and bottom surfaces and has a short connecting line.
Static electricity from inside the human body, the environment, and even electronic equipment can cause various damage to delicate semiconductor chips, such as penetrating a thin insulating layer inside the component; damaging the gates of MOSFETs and CMOS components; and flip-flops in CMOS devices Short-circuited, reverse-biased PN junction; short-circuited forward-biased PN junction; melted weld line or aluminum wire inside the active device. In order to eliminate the interference and destruction of electronic devices by electrostatic discharge (ESD), various technical means are needed to prevent them.
In the design of the PCB board, the anti-ESD design of the PCB can be realized by layering, proper layout and installation. In the design process, most of the design modifications can be limited to increasing or decreasing components through prediction. ESD can be well protected by adjusting the PCB layout. Here are some common precautions.
* Use multi-layer PCB as much as possible. Compared to double-sided PCB, the ground plane and power plane, as well as the tightly arranged signal line-ground spacing, can reduce the common mode impedance and inductive coupling to achieve a double-sided PCB. /10 to 1/100. Try to keep each signal layer close to a power or ground plane. For high-density PCBs with components on the top and bottom surfaces, short traces, and many fill locations, consider using inner traces.
* For double-sided PCBs, use a tightly interwoven power and ground grid. The power co
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