Circuit design skills PCB ontwerpproses

Algemene PCB basiese ontwerpproses is soos volg: voorlopige voorbereiding ->; PCB structure design -& GT; PCB -uitleg – & gt; Bedrading – & gt; Routeringsoptimalisering en skermdruk -> Network and DRC inspections and structural inspections – > Plate making.

First: preparation. This includes preparing component libraries and schematics. “To do good work, must first sharpen its device”, to make a good board, in addition to the principle of good design, but also draw well. Before PCB design, the component library of schematic SCH and the component library of PCB should be prepared first. Peotel libraries can be used, but in general it is difficult to find a suitable library, it is best to make your own library according to the standard size information of the selected device. In principle, make PCB component library first, and then SCH component library. Die vereistes van die PCB -komponentbiblioteek is hoog; dit beïnvloed die installasie van die bord direk; SCH’s component library requirements are relatively loose, as long as attention is paid to the definition of pin attributes and the corresponding relationship with PCB components. PS: Note the hidden pins in the standard library. Dan is die skematiese ontwerp gereed om PCB -ontwerp te doen.

Tweedens: PCB -strukturele ontwerp. In hierdie stap, volgens die grootte van die printplaat en meganiese posisionering, word die PCB -bordoppervlak in die PCB -ontwerpomgewing geteken, en word verbindings, knoppies/skakelaars, skroefgate, monteergate, ensovoorts volgens posisioneringsvereistes geplaas. And fully consider and determine the wiring area and non-wiring area (such as how much of the screw hole around the non-wiring area).

Derde: PCB -uitleg. Layout is basically putting devices on a board. At this point, if all the preparatory work mentioned above is done, the network table can be generated on the schematic diagram (Design- >; CreateNetlist) en voer dan die netwerktabel in op die PCB-diagram (design-gt; LoadNets). Sien die apparaat se geraas van die hele stapel, tussen die penne en die vlieglyn se vinnige verbinding. U kan die toestel dan uitlê. Die algemene uitleg word volgens die volgende beginsels uitgevoer:

(1). According to the electrical performance reasonable partition, generally divided into: digital circuit area (that is, afraid of interference, and interference), analog circuit area

(fear of interference), power drive area (interference source);

(2). Complete the same function of the circuit, should be placed as close as possible, and adjust the components to ensure the most simple connection; At the same time, adjust the relative position between the functional blocks to make the connection between the functional blocks the most concise;

(3). Installation position and installation intensity should be considered for components with large mass; Die verwarmingselement moet van die temperatuurgevoelige element geskei word, en indien nodig, moet termiese konveksiemaatreëls oorweeg word;

(4). I/O drive device as close as possible to the edge of the printing plate, close to the outlet connector;

(5). Clock generator (such as: crystal oscillator or clock oscillator) should be as close as possible to the device using the clock;

6. In each integrated circuit between the power input pin and the ground, need to add a decoupling capacitor (generally using high frequency good monolithic capacitor); ‘N Tantaalkondensator kan ook rondom verskeie geïntegreerde stroombane geplaas word as die ruimte op die printplaat krap is.

Alle grondeienaars. Relay coil to add discharge diode (1N4148 can be);

Vandag. Layout requirements should be balanced, dense and orderly, not top-heavy or heavy

— Special attention should be paid to the actual size (area and height) of the components and the relative position of the components when placing the components to ensure the electrical performance of the circuit board and the feasibility and convenience of production and installation. At the same time, the above principles should be reflected

Under the premise, modify the placement of devices appropriately to make them neat and beautiful. For example, the same devices should be placed neatly and in the same direction, instead of being “strewn at random”. This step concerns the difficulty of board integral figure and next wiring degree, want to spend big effort to consider so. When layout, can make preliminary wiring first to not quite affirmative place, sufficient consideration.

Vierde: bedrading. Bedrading is die belangrikste proses in PCB -ontwerp. Dit sal die prestasie van die printplaat direk beïnvloed. In the process of PCB design, wiring generally has such three levels of division: the first is the distribution, which is the most basic requirement of PCB design. If the line is not cloth, get everywhere is flying line, it will be a unqualified board, can say that there is no entry. The second is the satisfaction of electrical performance. Dit is die standaard om te meet of ‘n printplaat gekwalifiseer is. This is after the distribution, carefully adjust the wiring, so that it can achieve the best electrical performance. Dan is daar estetika. As u bedradingskleed gekoppel is, het u ook nie die plek wat die prestasie van die elektriese toestelle beïnvloed nie, maar kyk moedeloos verby, voeg kleurvolle, helderkleurige kleure by, wat bereken hoe u elektriese toestel se prestasie goed is, maar wees steeds rommel in ander oë. This brings great inconvenience to testing and maintenance. Bedrading moet netjies en eenvormig wees, nie sonder reëls nie. Al hierdie moet bereik word in die konteks van die versekering van elektriese prestasie en voldoening aan ander individuele vereistes, anders is dit om die essensie te laat vaar. Bedrading moet volgens die volgende beginsels uitgevoer word:

(1). Oor die algemeen moet die kragkabel en die grondkabel eers gelei word om die elektriese werkverrigting van die printplaat te verseker. In die omvang wat die toestand toelaat, is die breedte van die kragtoevoer, gronddraad so ver as moontlik, die beste dat die gronddraad wyer is as die kraglyn, hulle verhouding is: gronddraad> kraglyn> seinlyn, gewoonlik is die seinlynwydte : 0.2 ~ 0.3 mm, die dunste breedte kan 0.05 ~ 0.07 mm bereik, die kraglyn is oor die algemeen 1.2 ~ 2.5 mm. Die PCB van ‘n digitale stroombaan kan gebruik word in ‘n stroombaan met wye grondgeleiers, dit wil sê ‘n grondnetwerk. (Analoog grond kan nie op hierdie manier gebruik word nie.)

(2). In advance, wire strict requirements (such as high frequency line) for wiring, input and output side line should avoid adjacent parallel, so as not to produce reflection interference. When necessary, ground wire should be added to isolate, and the wiring of two adjacent layers should be perpendicular to each other, which is easy to produce parasitic coupling in parallel.

(3). The oscillator housing should be grounded, and the clock line should be as short as possible, and not spread all over the place. Below the clock oscillation circuit, the special high-speed logic circuit should increase the area of the ground, and should not go to other signal lines, so that the surrounding electric field tends to zero;

(4). In order to reduce the radiation of high frequency signal, 45O broken line should be used as far as possible, instead of 90O broken line. (High requirements of the line also use double arc)

(5). Any signal line should not form a loop, if unavoidable, loop should be as small as possible; Seinlyn deur die gat moet so min as moontlik wees;

6. Die sleutellyn moet kort en dik wees, met beskerming aan beide kante.

Alle grondeienaars. When the sensitive signal and noise field signal are transmitted through flat cable, the method of “ground – signal – ground wire” is used.

Vandag. Test points should be reserved for key signals to facilitate production and maintenance testing

Pet-name ruby. After schematic diagram wiring is completed, wiring should be optimized; At the same time, after the preliminary network check and DRC check is correct, the ground wire is filled in the area without wiring, and a large area of copper layer is used as ground wire, and the unused places are connected with the ground as ground wire on the printed board. Or make it multi-layer board, power supply, grounding line each occupy a layer.

— PCB wiring process requirements

(1). lyn

Generally, the signal line width is 0.3mm(12mil), and the power line width is 0.77mm(30mil) or 1.27mm(50mil). Reël met

The distance between lines and between lines and pads should be greater than or equal to 0.33mm(13mil). In practical application, it should be considered to increase the distance when conditions permit; When the cabling density is high, it is advisable (but not recommended) to use two cables between IC pins. The width of the cables is 0.254mm(10mil), and the distance between the cables is not less than 0.254mm(10mil).

Under special circumstances, when the pin of the device is dense and the width is narrow, the line width and line spacing can be appropriately reduced.

(2). PAD (PAD)

The basic requirements of PAD and transition hole (VIA) are: the diameter of PAD is greater than 0.6mm than the diameter of hole; For example, universal pin type resistors, capacitors and integrated circuits, using disk/hole size 1.6mm/0.8mm (63mil/32mil), socket, pin and diode 1N4007, using 1.8mm/1.0mm (71mil/39mil). In practical application, it should be determined according to the size of the actual components. If conditions are available, the size of the pad can be appropriately increased. The installation aperture of the components designed on the PCB board should be about 0.2 ~ 0.4mm larger than the actual size of the pins.

(3). Through hole (VIA)

Generally 1.27mm/0.7mm(50mil/28mil);

When the wiring density is high, the hole size can be appropriately reduced, but not too small, can consider 1.0mm/0.6mm(40mil/24mil).

(4). Spacing requirements for pads, wires and through-holes

PADandVIA: ≥0.3mm (12mil)

PADandPAD: ≥0.3mm (12mil)

PADandTRACK: ≥0.3mm (12mil)

TRACKandTRACK: ≥0.3mm (12mil)

As die digtheid hoog is:

PADandVIA: ≥0.254mm (10mil)

PADandPAD: ≥0.254mm (10mil)

PADandTRACK: ≥0.254mm (10mil)

TRACKandTRACK: ≥0.254mm (10mil)

Vyfde: bedradingoptimalisering en skermdruk. “There is no best, only better”! Maak nie saak hoeveel moeite jy met die ontwerp doen nie, kyk daarna weer as jy klaar is, en jy sal steeds voel dat jy baie kan verander. ‘N Algemene ontwerpreël is dat optimale bedrading twee keer so lank neem as die aanvanklike bedrading. As u eers voel dat niks opgelos hoef te word nie, kan u koper plaas. PolygonPlane). Koper lê oor die algemeen gronddraad (let op die skeiding van analoog en digitaal grond), kan dit ook nodig is om meerlaagse krag te plaas. Vir die druk van die skerm, moet ons daarop let dat dit nie deur die toestel geblokkeer word nie, of deur die gat en pad verwyder word. Terselfdertyd, ontwerp om die komponent oppervlak te kyk, moet die onderkant van die woord spieëlverwerking wees, om nie die vlak te verwar nie.

Sesde: netwerk- en DRK -kontrole en struktuurkontrole. Eerstens, op die uitgangspunt dat die skematiese ontwerp korrek is, is die gegenereerde PCB -netwerklêers en skematiese netwerklêers NETCHECK vir die fisiese verbindingsverhouding, en die ontwerp word betyds gewysig volgens die uitsetlêerresultate om die korrektheid van die bedradingverbinding te verseker; Nadat die netwerkondersoek korrek geslaag is, word die DRC -kontrole uitgevoer op die PCB -ontwerp, en die ontwerp sal betyds gewysig word volgens die uitsetlêerresultate om die elektriese werkverrigting van die PCB -bedrading te verseker. Laastens moet die meganiese installasiestruktuur van PCB verder nagegaan en bevestig word.

Sewende: bordmaak. It is best to have a review process before doing so.

PCB -ontwerp is ‘n toets van die verstand van die werk, wat na aan die verstand is, hoë ervaring, die ontwerp van die bord is goed. Dus die ontwerp moet uiters versigtig wees, ten volle die faktore van alle aspekte in ag neem (soos om die instandhouding en inspeksie hiervan te vergemaklik, wat baie mense nie oorweeg nie), uitnemendheid, sal ‘n goeie bord kan ontwerp.