Circuit design skills PCB design process

General PCB basic design process is as follows: preliminary preparation – >; PCB structure design -& GT; Tata perenah PCB – & GT; Kabel – & gt; Optimisasi pangarahan sareng percetakan layar -> 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. Sacara prinsip, ngadamel perpustakaan komponén PCB heula, teras perpustakaan komponén SCH. Persyaratan perpustakaan komponén PCB tinggi, éta langsung mangaruhan pamasangan dewan; 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. Teras nyaéta desain skéma, siap ngalakukeun desain PCB.

Kadua: Desain struktural PCB. Dina léngkah ieu, numutkeun ukuran papan sirkuit sareng posisi mékanis, permukaan papan PCB digambar dina lingkungan desain PCB, sareng konektor, tombol / saklar, liang sekrup, liang majelis sareng sajabina ditempatkeun numutkeun sarat posisi. 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).

Katilu: perenah PCB. 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), teras impor tabel jaringan dina diagram PCB (design-gt; LoadNets). Tingali hubbub alat tina tihang sadayana, antara pin sareng sambungan ajakan garis ngapung. Anjeun teras tiasa iklaskeun alatna. Tata perenah umum dilaksanakeun numutkeun prinsip ieu:

(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; Unsur pemanasan kedah dipisahkeun tina unsur sénsitip suhu, sareng upami perlu, ukuran konveksi termal kedah dipertimbangkeun;

(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); Kapasitor tantalum ogé tiasa ditempatkeun di sakitar sababaraha sirkuit terpadu nalika ruang circuit board sempit.

Sadaya anu gaduh bumi. Relay coil to add discharge diode (1N4148 can be);

Dinten. 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.

Kaopat: kabel. Wiring mangrupikeun prosés anu paling penting dina desain PCB. Ieu sacara langsung bakal mangaruhan kinerja dewan PCB. Dina prosés desain PCB, kabel umumna ngagaduhan tilu tingkat pembagian: anu munggaran nyaéta distribusi, anu mangrupikeun sarat paling dasar dina desain 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. Ieu standar pikeun ngukur naha papan sirkuit cetak mumpuni. This is after the distribution, carefully adjust the wiring, so that it can achieve the best electrical performance. Teras aya éstétika. If your wiring cloth was connected, also do not have the place that what affects electric appliance performance, but look past desultorily, add colourful, brightly colored, that calculates how your electric appliance performance is good, still be rubbish in others eye. This brings great inconvenience to testing and maintenance. Sambungan kabel kedah rapih sareng seragam, henteu paselang tanpa aturan. Sadaya ieu kedah dihontal dina kontéks mastikeun kinerja listrik sareng nyumponan sarat individu anu sanés, upami henteu pikeun nyingkahan intina. Wiring kedah dilaksanakeun numutkeun prinsip ieu:

(1). Sacara umum, kabel listrik sareng kabel darat kedah dialihkeun heula pikeun mastikeun kinerja listrik tina circuit board. Dina ruang lingkup anu ngamungkinkeun kondisina, ngalegaan lebar catu daya, kawat taneuh sajauh-jauhna, langkung saéna yén kawat taneuh langkung lega tibatan jalur listrik, hubunganana nyaéta: kawat darat> garis listrik> garis sinyal, biasana lébar garis sinyalna nyaéta : 0.2 ~ 0.3mm, lebar anu paling ipis tiasa ngahontal 0.05 ~ 0.07mm, garis listrikna 1.2 ~ 2.5mm umumna. 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; Garis sinyal ngaliwatan liang kedah sakedik mungkin;

6. Garis koncina kedah pondok sareng kandel, kalayan panyalindungan dina dua sisi.

Sadaya anu gaduh bumi. When the sensitive signal and noise field signal are transmitted through flat cable, the method of “ground – signal – ground wire” is used.

Dinten. 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). garis

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)

PADandPAD: ≥0.3mm (12mil)

PADandTRACK: ≥0.3mm (12mil)

TRACKandTRACK: ≥0.3mm (12mil)

Nalika kapadetan tinggi:

PADandVIA: ≥0.254mm (10mil)

PADandPAD: ≥0.254mm (10mil)

PADandTRACK: ≥0.254mm (10mil)

TRACKandTRACK: ≥0.254mm (10mil)

Kalima: optimasi kabel sareng percetakan layar. “Teu aya anu saé, ngan ukur langkung saé”! Perkara kumaha usaha anjeun dina desain, saatos réngsé, tingali deui, sareng anjeun bakal tetep ngarasa anjeun tiasa robih pisan. Aturan desain umum ngeunaan jempol nyaéta kabel optimum peryogi dua kali salami kabel awal. Sakali anjeun ngaraos yén teu aya anu peryogi ngalereskeun, anjeun tiasa nempatkeun tambaga. PolygonPlane). Peletakan tambaga umumna neundeun kawat taneuh (perhatoskeun pamisahan taneuh analog sareng digital), papan multilayer ogé panginten kedah nempatkeun kakuatan. Pikeun nyetak layar, urang kedah merhatoskeun supaya teu diblokir ku alat atanapi dipiceun ku liang sareng bantalan. Dina waktos anu sasarengan, desain nyanghareupan permukaan komponén, handapeun kecap kedah ngolah eunteung, supados henteu lieur tingkat na.

Kagenep: jaringan sareng DRC mariksa sareng struktur mariksa. Anu mimiti, dina premis yén desain skéma anu leres, file jaringan PCB anu dihasilkeun sareng file jaringan skéma anu NETCHKO pikeun hubungan hubungan fisik, sareng desainna dirobih dina waktosna sesuai sareng hasil file kaluaran pikeun mastikeun leresna hubungan sambungan kabel; Saatos cek jaringan diliwatan leres, DRC check bakal dilaksanakeun dina desain PCB, sareng desainna bakal dirobih numutkeun hasil file output dina waktosna kanggo mastikeun kinerja listrik kabel PCB. Tungtungna, struktur instalasi mékanis PCB kedah langkung diparios sareng dikonfirmasi.

Katujuh: ngadamel piring. It is best to have a review process before doing so.

Desain PCB mangrupikeun uji tina pikiran padamelan, anu caket kana pipikiran, pangalaman tinggi, desain dewan saé. Janten desainna kedah ati-ati pisan, sapinuhna mertimbangkeun faktor sadaya aspek (sapertos mempermudah pangropéa sareng pamariksaan ieu seueur jalma anu henteu nganggap), kaunggulan, bakal tiasa ngarancang papan anu saé.