Seektronics

1.  PCB board surface treatment   PCB board surface treatment processes include: anti-oxidation, spray tin, lead-free spray tin, sink gold, sink tin, sink silver, hard gold plating, full-board gold plating, gold finger, nickel-palladium-gold OSP, etc.. Requirements are mainly: lower cost, good solderability, harsh storage conditions, short time, environmentally friendly processes, good welding, flat . Tin spraying: Tin spraying boards are generally multi-layer (4-46 layers) high precision PCB prototype boards, which have been used by many large domestic communication, computer, medical equipment and aerospace companies and research units.   The connecting finger is the component on the memory stick that connects to the memory slot, and all signals are transmitted through the gold finger. Gold fingers are composed of numerous gold-colored conductive contacts, which are called "gold fingers" because of their gold-plated surface and the finger-like arrangement of the conductive

PCB board, mainly in order to make full use of the board, so as to improve production efficiency.   Relatively simple is the rule of the plate frame of the plate.     As shown in the picture above, the board frame is square, and it is easy to assemble four boards, among which, only one board needs wiring, while the other boards only need the frame, which the sample factory will handle (it is better to copy the components and lines in the past, so that it is not easy to make mistakes).   The lines in the mechanical layer of the regular plate frame are cut by the Vcut knife, but the plate thickness of 0.4mm cannot be cut by the Vcut knife.   What if it's an irregular frame?   In the picture above, stamp holes (with five circles) are used. I used a circle with a radius of 0.4mm and a line width of 0.127mm. The spacing between the circles is about 10mil, not too wide. In this way, the plate factory will drill holes in the rings, so that the hand can easily break it.   For the lines in

  Protel 99 SE provides 32 signal layers, including the Top layer, Bottom layer and 30  M iddle layer.   Top signal layer: also known as the component layer, mainly used to place components, for multilayer boards can be used for wiring.   Mid Signal Layer: up to 30 layers, used to lay signal lines in multilayer boards.   The bottom signal layer : also known as the solder layer, mainly used for wiring and soldering, and sometimes can also be placed on the components.   Silkscreen layer: The silkscreen layer is mainly used for placing printed information, such as component outline and labeling, various comment characters, etc. Protel 99 SE provides two silkscreen layers, Top Overlay and Bottom Overlay. Generally, various annotation characters are placed on the top screen printing layer, and the bottom screen printing layer can be closed.   Top silkscreen layer: used to mark the projected outline of the component, the component's mark, nominal value or model number and various comment

Via in pad   as the name implies, is to hit the hole in the pad, with the increasing integration of electronic products, the components package is getting smaller and smaller, especially in complex PCB design pin spacing is too small, not hit the plate in the hole can not fan out, then you must hit the plate in the hole, from the next layer out of the line.   In the drawing of the PCB, the plate in the hole is nothing special, is over the hole in the pad, but there are several types of PCB production and processing processes, as hardware engineers must understand.   The most common hole in the plate   Is the hole in the pad, the production of PCB does not require a special process, the pad will leave a "hole eye", if the hole eye is too large may cause tin leakage problems, may also lead to false soldering problems, this process is the cheapest and most common, as follows QFN package on the heat sink hole.   Resin plugging hole + copper plating cap   This type of plate-in-the

  Electronic devices will generate a certain amount of heat when working, so that the internal temperature of the device rises rapidly, if the heat is not distributed in a timely manner, continued heating, the device will fail due to overheating, the reliability of electronic equipment performance will be reduced. Therefore, a good thermal treatment of PCB circuit boards is very important.         1.  PCB heat dissipation itself   PCB heat dissipation is a simple, practical, low-cost way to dissipate heat. The current PCB circuit board is mainly: copper/epoxy glass cloth substrate or phenolic resin glass cloth substrate, although these substrates have excellent electrical properties and processing performance, but poor heat dissipation can hardly be expected to conduct heat by the PCB itself resin. Therefore, it needs to be designed to dissipate heat from the surface of the component to the surrounding air.   So how to do it? The best way to improve the direct contact with the heat-gen