One of the Design Guidelines for High Speed PCB Boards

One of the Design Guidelines for High Speed PCB Boards
p> In the design of printed circuit board boar d d, wiring is an important step to complete the product d design It can be said that all the preparations before D have been completed In a word, boar d of printed circuit board has a very limited design process The boar d wiring of the printed circuit board includes des single silicon ed wiring, d double silicon ed wiring and d multi-layer wiring There are also two routing pipelines: automatic routing and d interactive routing Before automatic wiring, interactive pre wiring can be used for lines with stricter requirements The gesd-d output end of the ed input En should be d A-D adjacent and avoi similar d reflection interference If necessary, the insulation of the GREEN D wire should d become dded, the wiring of one d and two a d, the jacquard layer d is imprisoned d, and the parasitic coupling of one d can easily occur in parallel The routing rate of automatic routing is d Eben dIt 'He is very happy with the layout of d You can preset routing rules, including the number, trace, number of through-hole, and number of steps Generally, exploratory wiring is in progress. First, a d short line can quickly connect d, and then a d maze wiring is in progress - d Try re routing to improve the overall effect At present, boar d d design of high density printed circuit board thinks that through hole is not suitable It wastes many valuable wiring channels It also saves many wiring channels, making the wiring process more convenient and smooth The D design process of printed circuit board boar DS is a complex and simple process Engineering designers can only understand its true meaning through personal experience
Power supply treatment

Even if the wiring is perfect on the entire PCB, d, the cause of interference d, due to the lack of careful consideration of d, the operation of the power supply d, and d, the cable will be reconnected to the efficiency of the product, d, and sometimes even affect the success rate of the product Therefore, the power supply wiring d, the GREEN D wire should be taken seriously, d, the noise interference generated d, the power d, the GREEN D wire should be re educated to ensure the product quality to the minimum Every participating engineer d in the design of this d electronic product products United Nations d Elstein d What is the cause of the noise between the ground d wire d At present, only the reduced noise suppression is obvious:
1) It is well known to add d power supply and d GREEN d wire
2.) Try to wid is the d rd grid wire of wid power, preferably the ground d wire is wid er than the power wire ï ½ž 0.07mm, power cord is 1.2 ï ½ž 2.5 mm, one d This printed circuit board boar d d can use digital circuit d and wi to form a ring d Glenn d wire, that is, group d net can use d (the Glenn d analog circuit cannot use d in this way)
3.) Use a large area copper layer as a group d wire, one d connects the unused d printing position d boar d to the ground d as a gray d wire Or make multilayer boar d, power supply, and each conductor of Gran d occupies one layer
2. Common group d processing d digital circuit d analog circuit
Now, before that, there were m-y printed circuit board boars ds that are no longer a single function loop (digital or log loop), which formed a d mixed d digital and d log circuit Therefore, it is necessary to consider the mutual interference between d er and them during wiring, especially the noise interference d wire on the ground The frequency of D digital circuit is high, and the sensitivity of D analog circuit is strong For signal lines, high-frequency signal lines should be d away from sensitive analog circuits d as much evidence as possible For the sake of the global d line, there is only one boar d on the overall printed circuit board, and there is no d to go outside to the d world d Therefore, the problem d digital analogy public ground d must be d and InWest cooperation de printed circuit board boar d, a d the d digital ground d d analogy ground d is actually separate d inside boar d, a d they have no contact d each other, only in printed circuit board boar d d outdoor d world d (such as plug) Wait).  The d digit on the ground d is a little short to the analog group d. Please note that there is only one connection point There is also no common point on the printed circuit board boar d, which is d forever d designed according to system d
3. The signal line is the electrical (ground) layer on route d
In the wiring of multi layer printed boar ds, because there are not too many lines left in the signal line layer, adding more layers will cause waste and d will add prod construction work, d and d cost will add Accor d Yingli To solve this conflict, we can consider der wiring on the electrical (ground) layer The power aircraft should consider d first before d, and follow d aircraft Because it is better to keep the integrity of the stratum
4. Connecting conductors of Han people's large connecting legs
In a large area of grounding (electricity There are some Angry D components in the world, such as: 1) Welding needs high-power heaters 2) It is easy to cause virtual solver connector Therefore, considering the power efficiency, d process needs, cross shaped d Pads, are you mom de, and which are called thermal isolation d are usually called thermal pads In this way, the possibility of virtual sol, der joint cause, d overheating, d loss of cross section, d Urwelding, can be greatly reused The electrical (ground) leg of a multilayer boar d is treated
5. The role of the network system in wiring
In m-y CAD systems, the wiring is d forever d through the network system If the grid is also a D N, although the number of channels is increasing, the steps are too small. The number of D channels per d is too large, and the atad in the image field is too large. This must have higher requirements for the storage space of the device. A D channel will also affect the computing speed Influence - d Some through holes fail, for example, those occupied d pass through the pad component leg or occupied d pass through the mounting hole, positioning hole, etc Too sparse gridsd and too few paths will affect the allocation rate of d Therefore, there must be a reasonable grid system density to support wiring The distance between the two legs of the standard component is 0.1 inch (2.54mm). In retrospect, the basic d system of gri is usually set to 0.1 inches (2.54mm) or less th -- integral multiple of 0.1 inches, such as 0.05 inch, 0.025 inch, 0.02 inch, etc
6.. Design Rule Checking (DRC)
After the wiring d design is completed, it is necessary to carefully check whether the wiring is correct design complies with the established rules d by d designer, and also need to confirm whether the rules are formulated d meet the requirements of printed matter d boar d prod construction process Generally, check the following: d:
1) Where the d distance between lines d wire, wire d component pad, wire d through-hole, component pad and through-hole, and through-hole d through-hole is reasonable, and whether it meets the requirements of professionals d construction requirements
2) Are the proper wires and wires a kind of power? Where is there a printed circuit board in the world? Where can the d wire be a wid alkene d?
3) When the best measures have been taken for the key signal lines
4) Where the analog circuit and the digital circuit part has its own ear nose throat wire
5) Which the graphics (such as icons, labels) added to the printed circuit board boar d will cause the signal short circuit
6) Mod identifies some unsatisfactory line shapes
7) Is there a process line on the PCB boar d? No matter whether the sol der mask meets the requirements of pro d construction process, no matter whether the size of the sol der mask is appropriate, whether the and symbol is pressed d on the d evidence d, so as not to affect the power quality
8) The layer boar d in the ged multilayer of the outer frame of the generator set is duced, for example, the copper foil d of the power supply ground is exposed layer by layer d Aoxi de the boar d, which is easy to cause short circuit
High speed d circuit d design is a very complicated process Method D D Description D This paper specifically aims at solving these high-speed d circuit d design problems In add Eaton, there are several factors that need to be considered: d, when to design high-speed d circuits, and these factors are sometimes opposed to each other If the speed is fast, d d evidence is in place and d is close, d Elise can conduct again, but crosstalk d may have a significant thermal effect Therefore, in design, it is necessary to weigh various factors d to make a comprehensive compromise d operation; It not only meets the requirements of D design, but also leads to the complexity of D design High speed use of  printed circuit board d design method ds to form the controllable d design process of the system Only controllable is reliable and successful