Circuit design skills PCB design process

General PCB basic design process is as follows: preliminary preparation – >; PCB structure design -& GT; Uyilo lwePCB- & gt; Iingcingo – & gt; Ukulungiswa kwendlela kunye nokuprinta kwescreen-> 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. Ngokomgaqo, yenza icandelo lethala leencwadi le-PCB kuqala, emva koko emva koko lilungu lethala lencwadi le-SCH. Icandelo leemfuno zethala leencwadi le-PCB liphezulu, lichaphazela ngokuthe ngqo ukufakelwa kwebhodi; 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. Ke uyilo loyilo, olulungele ukwenza uyilo lwePCB.

Okwesibini: uyilo lolwakhiwo lwePCB. Kweli nqanaba, ngokobungakanani bebhodi yesekethe kunye nokubekwa koomatshini, indawo yebhodi yePCB ityhilwe kwimeko yoyilo lwePCB, kunye nezihlanganisi, amaqhosha / ukutshintsha, imingxunya yokujija, imingxunya yendibano njalo njalo ibekwa ngokweemfuno zokubeka. 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).

Okwesithathu: Ubeko lwePCB. 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- >; Yenza iNetlist), emva koko ungenise itafile yenethiwekhi kumzobo wePCB (uyilo-gt; Imithwalo eLayishayo). Jonga isixhobo esixineneyo sayo yonke loo mfumba, phakathi kwezikhonkwane kunye nomda wokudibanisa umgca wokuhamba. Ungabeka isixhobo. Uyilo ngokubanzi lwenziwa ngokwale migaqo ilandelayo:

(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; Izinto zokufudumeza kufuneka zahlulwe kubushushu obuzwayo, kwaye ukuba kukho imfuneko, amanyathelo okuhambisa ubushushu kufuneka athathelwe ingqalelo;

(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); I-tantalum capacitor inokufakwa kwindawo ejikeleze iisekethe ezininzi xa indawo yebhodi yesekethe iqinile.

Bonke abanini mhlaba. Relay coil to add discharge diode (1N4148 can be);

Namhlanje. 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.

Okwesine: iintambo. Iingcingo yinkqubo ebaluleke kakhulu kuyilo PCB. Oku kuya kuchaphazela ngokuthe ngqo ukusebenza kwebhodi ye-PCB. Kwinkqubo yoyilo lwe-PCB, i-wiring ngokubanzi inamanqanaba amathathu okwahlulahlula: eyokuqala kukusasazwa, eyona nto isisiseko kuyilo lwe-PCB. 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. Lo ngumgangatho wokulinganisa ukuba ibhodi yesekethe eprintiweyo iyafaneleka. This is after the distribution, carefully adjust the wiring, so that it can achieve the best electrical performance. Emva koko kukho ubuhle. Ukuba ilaphu lakho le-wiring belidityanisiwe, nayo ayinayo indawo echaphazela ukusebenza kwesixhobo sombane, kodwa jonga ngaphaya kokungathandekiyo, yongeza imibala, eqaqambileyo, ebala ukuba intle into yokusebenza kwesixhobo sombane, iseyinkunkuma kwabanye iliso. This brings great inconvenience to testing and maintenance. Iingcingo kufuneka zihlale zicocekile kwaye zifanane, hayi kwi-crisscross ngaphandle kwemithetho. Zonke ezi zinto kufuneka zifezekiswe kwimeko yokuqinisekisa ukusebenza kombane kunye nokuhlangabezana nezinye iimfuno zomntu ngamnye, kungenjalo kukushiya isiseko. Iingcingo kufuneka zenziwe ngokwale migaqo ilandelayo:

(1). Ngokubanzi, intambo yombane kunye nentambo yomhlaba kufuneka ihanjiswe kuqala ukuqinisekisa ukusebenza kombane kwibhodi yesekethe. Kwindawo apho imeko ivumayo, wandise ububanzi bokunikezelwa kwamandla, ucingo lomhlaba kangangoko kunokwenzeka, kungcono ukuba ucingo lomhlaba lubanzi kunelayini yamandla, ubudlelwane babo yile: yocingo lomhlaba> umgca wamandla> umgca womqondiso, uhlala ulayini womqondiso : 0.2 ~ 0.3mm, ububanzi obuncinci bunokufikelela kwi-0.05 ~ 0.07mm, umgca wamandla ngu-1.2 ~ 2.5mm ngokubanzi. The PCB of a digital circuit can be used in a circuit with wide ground conductors, that is, a ground network. (Analog ground cannot be used in this way.)

(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; Umgca wokutyikitya emngxunyeni kufuneka ubencinci kangangoko;

6. Umgca ophambili kufuneka ube mfutshane kwaye ungqindilili, ukhuseleko macala omabini.

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

Namhlanje. 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. Okanye yenze ibhodi yomaleko omninzi, unikezelo lwamandla, umgca womhlaba ngamnye uhlala kwilayini.

— PCB wiring process requirements

(1). umgca

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

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)

IPADPAD: ≥0.3mm (12mil)

I-PADandTRACK: ≥0.3mm (12mil)

TRACKandTRACK: ≥0.3mm (12mil)

Xa uxinano luphezulu:

PADandVIA: ≥0.254mm (10mil)

IPADPAD: ≥0.254mm (10mil)

I-PADandTRACK: ≥0.254mm (10mil)

TRACKandTRACK: ≥0.254mm (10mil)

Okwesihlanu: ukwenziwa kweentambo kunye nokushicilelwa kwescreen. “Akukho nto ibhetele, kungcono kuphela”! Nokuba ungakanani na umzamo owenzayo kuyilo, xa ugqibile, jonga kwakhona, kwaye uya kuziva ukuba ungatshintsha kakhulu. Umgaqo woyilo ngokubanzi wesithupha kukuba i-wiring efanelekileyo ithatha kabini ubude njenge-wiring yokuqala. Nje ukuba uve ukuba akukho nto ifuna ukulungiswa, ungabeka ubhedu. IPolygonPlane). Ukubeka ubhedu ngokubanzi kubeka ucingo lomhlaba (jonga ukwahlula i-analog kunye nomhlaba wedijithali), ibhodi ye-multilayer inokufuna ukubeka amandla. Ukuprintwa kwesikrini, kuya kufuneka sinike ingqalelo ekungavinjelweni sisixhobo okanye sisuswe ngomngxunya nakwiphedi. Kwangelo xesha, uyilo lokujongana nomphezulu wecandelo, emazantsi eli gama kufuneka kube kusenziwa isipili, ukuze ungabhidanisi inqanaba.

Okwesithandathu: uthungelwano kunye nokuhlolwa kweDRC kunye nokuhlolwa kobume. Okokuqala, kwingqikelelo yokuba uyilo lwesikimu luchanekile, iifayile zenethiwekhi zePCB kunye neefayile zenethiwekhi zesikimu zi-NETCHECK yolwalamano lonxibelelwano, kwaye uyilo luhlengahlengiswa kwangexesha ngokweziphumo zefayile yokuvelisa ukuqinisekisa ukuchaneka kobudlelwane bokunxibelelana kweentambo; Emva kokuba uthungelwano lwenethiwekhi lupasiswe ngokuchanekileyo, i-DRC itshekhi iya kwenziwa kuyilo lwe-PCB, kwaye uyilo luya kulungiswa ngokweziphumo zefayile yemveliso ngexesha lokuqinisekisa ukusebenza kombane kwe-PCB ye-wiring. Okokugqibela, ulwakhiwo lofakelo loomatshini lwe-PCB kufuneka luhlolwe ngakumbi kwaye luqinisekiswe.

Okwesixhenxe: ukwenziwa kweplate. It is best to have a review process before doing so.

Uyilo lwe-PCB luvavanyo lwengqondo yomsebenzi, osondele engqondweni, amava aphezulu, uyilo lwebhodi lulungile. Ke uyilo kufuneka lube ngononophelo olukhulu, luqwalasele ngokupheleleyo imiba yayo yonke imiba (enje ngokuququzelela ulondolozo kunye nokuhlolwa koku uninzi lwabantu alukuthatheli ngqalelo), ukugqwesa, kuya kuba nakho ukuyila ibhodi elungileyo.