In design, layout is an important part. The quality of the layout result will directly affect the effect of the wiring, so it can be considered that a reasonable layout is the first step to a successful PCB design. Especially the pre-layout is the process of thinking about the entire circuit board, signal flow, heat dissipation, structure and other structures. If the pre-layout fails, no amount of effort will be needed.

PCB layout design The design process flow of printed circuit boards includes schematic design, electronic component database registration, design preparation, block division, electronic component configuration, configuration confirmation, wiring and final inspection. In the process of the process, no matter which process is found to be a problem, it must be returned to the previous process for reconfirmation or correction.

Lesi sihloko sethula kuqala imithetho nezindlela zokwakheka kwesakhiwo se-PCB, bese sichaza indlela yokuklama nokuhlola ukwakheka kwe-PCB, kusukela ezidingweni ze-DFM zesakhiwo, izidingo zedizayini ezishisayo, izidingo zobuqotho besignali, izidingo ze-EMC, izilungiselelo zesendlalelo kanye nezidingo zokuhlukaniswa kwamandla, kanye amamojula amandla. Izidingo kanye nezinye izici zizohlaziywa ngokuningiliziwe, bese ulandela umhleli ukuze uthole imininingwane.

Imithetho yokuklama isakhiwo se-PCB

1. Ngaphansi kwezimo ezijwayelekile, zonke izingxenye kufanele zihlelwe endaweni efanayo yebhodi lesifunda. Kuphela uma izingxenye zeleveli ephezulu ziminyene kakhulu, lapho amanye amadivayisi anobude obukhawulelwe kanye nokukhiqiza ukushisa okuphansi, njengezihluthulelo ze-chip, ama-chip capacitor, nama-chip capacitor, angafakwa. I-Chip IC, njll. ibekwe kungqimba olungezansi.

2. Ngaphansi kwesisekelo sokuqinisekisa ukusebenza kukagesi, izingxenye kufanele zibekwe kugridi futhi zihlelwe ngokuhambisana noma i-perpendicular komunye nomunye ukuze zibe zinhle futhi zihle. Ngaphansi kwezimo ezijwayelekile, izingxenye azivunyelwe ukugqagqana; ukuhlelwa kwezingxenye kufanele kuhlanganiswe, futhi izingxenye kufanele zihlelwe kuwo wonke ukwakheka. Ukusabalalisa kufana futhi kuminyene.

3. The minimum distance between adjacent land patterns of different components on the circuit board should be above 1mm.

4. Ibanga elisuka emaphethelweni ebhodi lesifunda ngokuvamile alikho ngaphansi kuka-2MM. Umumo omuhle kakhulu webhodi lesifunda unonxande, futhi i-aspect ratio ingu-3:2 noma 4:3. Uma usayizi webhodi lesifunda mkhulu kuno-200MM ngo-150MM, cabanga ngalokho ibhodi lesifunda elingakwazi ukumelana namandla oMechanical.

PCB layout design skills

Ekwakhiweni kwesakhiwo se-PCB, amayunithi ebhodi lesifunda kufanele ahlaziywe, futhi ukwakheka kwesakhiwo kufanele kusekelwe emsebenzini wokuqala. Lapho ubeka zonke izingxenye zesekethe, izimiso ezilandelayo kufanele zihlangatshezwe:

1. Hlela isikhundla seyunithi ngayinye yesifunda esisebenza ngokuhambisana nokugeleza kwesifunda, ukuze ukuhlelwa kukulungele ukujikeleza kwesignali, futhi isignali igcinwe endaweni efanayo ngangokunokwenzeka [1].

2. Take the core components of each functional unit as the center and lay out around him. The components should be uniformly, integrally and compactly arranged on the PCB to minimize and shorten the leads and connections between the components.

3. Kumasekethe asebenza kuma-frequencies aphezulu, imingcele yokusabalalisa phakathi kwezingxenye kufanele icatshangelwe. Ezingxenyeni ezijwayelekile, izingxenye kufanele zihlelwe ngokuhambisana ngangokunokwenzeka, okungeyona nje into enhle, kodwa futhi kulula ukuyifaka futhi kulula ukukhiqiza ngobuningi.

Indlela yokuklama nokuhlola isakhiwo se-PCB

1. DFM requirements for layout

1. The optimal process route has been determined, and all devices have been placed on the board.

2. The origin of the coordinates is the intersection of the left and lower extension lines of the board frame, or the lower left pad of the lower left socket.

3. The actual size of the PCB, the location of the positioning device, etc. are consistent with the process structure element map, and the device layout of the area with restricted device height requirements meets the requirements of the structure element map.

4. Ukuma kweswishi yokudayela, ukusetha kabusha idivayisi, ukukhanya kwenkomba, njll. kufanelekile, futhi ibha yesibambo ayiphazamisi kumadivayisi azungezile.

5. Uhlaka lwangaphandle lwebhodi lune-radian ebushelelezi engu-197mil, noma luklanywe ngokuhambisana nomdwebo wosayizi wesakhiwo.

6. Amabhodi ajwayelekile anemiphetho yenqubo engu-200mil; izinhlangothi ezingakwesokunxele nezingakwesokudla zendiza engemuva zineziphetho zenqubo ezingaphezu kuka-400mil, futhi izinhlangothi ezingenhla neziphansi zinemiphetho yenqubo engaphezu kuka-680mil. Ukubekwa kwedivayisi akungqubuzani nendawo yokuvula iwindi.

7. All kinds of additional holes (ICT positioning hole 125mil, handle bar hole, elliptical hole and fiber holder hole) that need to be added are all missing and set correctly.

8. Ukuphakama kwephinikhodi yedivayisi, isiqondiso sedivayisi, ukuphakama kwedivayisi, umtapo wolwazi wedivayisi, njll. okucutshungulwe ngokufakwa kwe-wave soldering kucabangela izidingo zokubethelwa kwamagagasi.

9. The device layout spacing meets the assembly requirements: surface mount devices are greater than 20mil, IC is greater than 80mil, and BGA is greater than 200mil.

10. Izingxenye zokucwilisa zinamamilimitha angaphezu kwe-120 ebangeni elingaphezulu lengxenye, futhi akukho divayisi endaweni yezingxenye zokugoqa endaweni yokushisela.

11. Awekho amadivayisi amafushane phakathi kwamadivayisi amade, futhi awekho amadivaysi okupeshisha kanye namadivaysi amafushane namancane afaka phakathi abekwe phakathi kuka-5mm phakathi kwamadivayisi anobude obungaphezu kuka-10mm.

12. Imishini ye-polar inamalogo we-polarity silkscreen. Izikhombisi-ndlela zika-X kanye no-Y zohlobo olufanayo lwezingxenye ze-plug-in ezihlukanisiwe ziyefana.

13. All devices are clearly marked, no P*, REF, etc. are not clearly marked.

14. Kunezikhombisi zokubeka ezi-3 endaweni equkethe amadivaysi e-SMD, abekwe ngendlela “L”. Ibanga phakathi kwesikhungo sekhesa yokumisa kanye nonqenqema lwebhodi likhulu kuno-240 mils.

15. Uma udinga ukwenza ukucutshungulwa kokugibela, ukwakheka kubhekwa njengokwenza kube lula ukugibela kanye nokucubungula kwe-PCB nokuhlanganisa.

16. Amaphethelo aqoshiwe (amaphethelo angajwayelekile) kufanele agcwaliswe ngokusebenzisa imisele yokugaya kanye nezimbobo zezitembu. Imbobo yesitembu iyisikhala esingeyona insimbi, ngokuvamile engamamitha angu-40 ububanzi namamitha angu-16 ukusuka onqenqemeni.

17. The test points used for debugging have been added in the schematic diagram, and they are placed appropriately in the layout.

Second, the thermal design requirements of the layout

1. Heating components and exposed components of the casing are not in close proximity to wires and heat-sensitive components, and other components should also be properly kept away.

2. The placement of the radiator takes into account the convection problem, and there is no interference of high components in the projection area of ​​the radiator, and the range is marked on the mounting surface with silk screen.

3. Isakhiwo sicabangela imigudu enengqondo futhi ebushelelezi yokukhipha ukushisa.

4. I-electrolytic capacitor kufanele ihlukaniswe kahle nedivayisi yokushisa okuphezulu.

5. Cabangela ukuchithwa kokushisa kwamadivayisi anamandla aphezulu kanye namadivayisi ngaphansi kwe-gusset.

Okwesithathu, izidingo zobuqotho besignali yesakhiwo

1. The start-end matching is close to the sending device, and the end matching is close to the receiving device.

2. Place decoupling capacitors close to related devices

3. Place crystals, crystal oscillators and clock drive chips close to related devices.

4. Isivinini esikhulu kanye nesivinini esiphansi, idijithali ne-analog zihlelwa ngokwehlukana ngokwamamojula.

5. Determine the topological structure of the bus based on the analysis and simulation results or the existing experience to ensure that the system requirements are met.

6. If it is to modify the board design, simulate the signal integrity problem reflected in the test report and give a solution.

7. The layout of the synchronous clock bus system meets the timing requirements.

Okwesine, izidingo ze-EMC

1. Inductive devices that are prone to magnetic field coupling, such as inductors, relays, and transformers, should not be placed close to each other. When there are multiple inductance coils, the direction is vertical and they are not coupled.

2. Ukuze ugweme ukuphazamiseka kukazibuthe phakathi kwedivayisi endaweni yokushisela ebhodini elilodwa kanye nebhodi elilodwa eliseduze, akukho mishini ebucayi kanye namadivaysi emisebe anamandla okufanele abekwe endaweni yokushisela yebhodi elilodwa.

3. The interface components are placed close to the edge of the board, and appropriate EMC protection measures have been taken (such as shielding shells, hollowing out of the power supply ground, etc.) to improve the EMC capability of the design.

4. Isifunda sokuvikela sibekwe eduze kwesekhethi yesixhumi esibonakalayo, ngokulandela isimiso sokuvikela kuqala bese siyahlungwa.

5. Ibanga ukusuka emzimbeni ovikelayo kanye negobolondo elivikelayo ukuya emzimbeni ovikelayo kanye negobolondo lekhava elivikelayo lingaphezu kwama-500 mils kumadivayisi anamandla okudlulisa aphezulu noma azwela kakhulu (njengama-crystal oscillator, amakristalu, njll.).

6. A 0.1uF capacitor is placed near the reset line of the reset switch to keep the reset device and reset signal away from other strong devices and signals.

Five, layer setting and power supply and ground division requirements

1. Uma izingqimba ezimbili zesignali zisondelene ngokuqondile, imithetho yezintambo eziqondile kufanele ichazwe.

2. Isendlalelo samandla esiyinhloko siseduze nongqimba lwaso lomhlabathi oluhambisanayo ngangokunokwenzeka, futhi ungqimba lwamandla luhlangabezana nomthetho we-20H.

3. Each wiring layer has a complete reference plane.

4. Amabhodi anezingqimba eziningi anama-laminated futhi i-core material (CORE) i-symmetrical ukuvimbela ukungqubuzana okubangelwa ukusatshalaliswa okungalingani kokuminyana kwesikhumba sethusi kanye nokuqina kwe-asymmetrical medium.

5. Ubukhulu bebhodi akufanele budlule u-4.5mm. Kulabo abanogqinsi olungaphezu kuka-2.5mm (i-backplane enkulu kuno-3mm), ochwepheshe bekufanele baqinisekise ukuthi ayikho inkinga ngokucubungula, ukuhlanganisa, kanye nemishini ye-PCB, futhi ukujiya kwebhodi lekhadi le-PC kungu-1.6mm.

6. Uma isilinganiso sogqinsi ukuya kububanzi be-via sikhulu kuno-10:1, sizoqinisekiswa umkhiqizi we-PCB.

7. The power and ground of the optical module are separated from other power and ground to reduce interference.

8. Amandla nokucubungula phansi kwezingxenye ezibalulekile kuhlangabezana nezidingo.

9. Uma ukulawulwa kwe-impedance kuyadingeka, imingcele yokubeka isendlalelo ihlangabezana nezidingo.

Six, power module requirements

1. The layout of the power supply part ensures that the input and output lines are smooth and do not cross.

2. Lapho ibhodi elilodwa linikeza amandla ebhodini elingaphansi, beka isifunda sokuhlunga esihambisanayo eduze nendawo yokuphuma kwamandla ebhodi elilodwa kanye nendawo yokufaka amandla ebhodini elincane.

Seven, other requirements

1. The layout takes into account the overall smoothness of the wiring, and the main data flow is reasonable.

2. Lungisa imisebenzi yephinikhodi yokungafakwa, i-FPGA, EPLD, umshayeli webhasi namanye amadivaysi ngokuya ngemiphumela yesakhiwo ukuze uthuthukise isakhiwo.

3. Isakhiwo sicabangela ukwanda okufanele kwesikhala kuzintambo eziminyene ukuze kugwenywe isimo sokuthi ngeke kuhanjiswe umzila.

4. Uma izinto ezikhethekile, izisetshenziswa ezikhethekile (ezifana ne-0.5mmBGA, njll.), kanye nezinqubo ezikhethekile zamukelwa, isikhathi sokulethwa kanye nokucutshungulwa kucatshangelwe ngokugcwele, futhi kwaqinisekiswa abakhiqizi be-PCB nabasebenzi benqubo.

5. The pin corresponding relationship of the gusset connector has been confirmed to prevent the direction and orientation of the gusset connector from being reversed.

6. If there are ICT test requirements, consider the feasibility of adding ICT test points during layout, so as to avoid difficulty in adding test points during the wiring phase.

7. When a high-speed optical module is included, the layout of the optical port transceiver circuit is prioritized.

8. Ngemva kokuba isakhiwo sesiqediwe, umdwebo wokuhlanganisa ongu-1:1 unikezwe izisebenzi zephrojekthi ukuze zihlole ukuthi ukukhetha kwephakheji yedivayisi kulungile yini uma kuqhathaniswa nebhizinisi ledivayisi.

9. Ekuvuleni kwefasitela, indiza yangaphakathi ibhekwa njengehlehlisiwe, futhi indawo efanelekile yokuvinjelwa kwezintambo isethiwe.