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.

Kifungu hiki kwanza kinatanguliza sheria na mbinu za muundo wa mpangilio wa PCB, na kisha kueleza jinsi ya kubuni na kukagua mpangilio wa PCB, kutoka kwa mahitaji ya DFM ya mpangilio, mahitaji ya muundo wa joto, mahitaji ya uadilifu wa ishara, mahitaji ya EMC, mipangilio ya safu na mahitaji ya mgawanyiko wa ardhi, na moduli za nguvu. Mahitaji na vipengele vingine vitachambuliwa kwa kina, na kumfuata mhariri ili kujua maelezo.

Sheria za muundo wa mpangilio wa PCB

1. Katika hali ya kawaida, vipengele vyote vinapaswa kupangwa kwenye uso sawa wa bodi ya mzunguko. Ni wakati tu vipengee vya kiwango cha juu ni vizito sana, ndipo baadhi ya vifaa vilivyo na urefu mdogo na uzalishaji wa joto la chini, kama vile vipingamizi vya chip, vishinikizo vya chip, na vishikiza chip, vinaweza kusakinishwa. Chip IC, nk huwekwa kwenye safu ya chini.

2. Chini ya msingi wa kuhakikisha utendaji wa umeme, vipengele vinapaswa kuwekwa kwenye gridi ya taifa na kupangwa sambamba au perpendicular kwa kila mmoja ili kuwa nadhifu na nzuri. Katika hali ya kawaida, vipengele haviruhusiwi kuingiliana; mpangilio wa vipengele unapaswa kuwa compact, na vipengele vinapaswa kupangwa kwenye mpangilio mzima. Usambazaji ni sare na mnene.

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

4. Umbali kutoka kwa makali ya bodi ya mzunguko kwa ujumla sio chini ya 2MM. Sura bora ya bodi ya mzunguko ni mstatili, na uwiano wa kipengele ni 3: 2 au 4: 3. Wakati saizi ya bodi ya mzunguko ni kubwa kuliko 200MM kwa 150MM, fikiria kile bodi ya mzunguko inaweza kuhimili nguvu za Mitambo.

PCB layout design skills

Katika muundo wa mpangilio wa PCB, vitengo vya bodi ya mzunguko vinapaswa kuchambuliwa, na muundo wa mpangilio unapaswa kutegemea kazi ya kuanzia. Wakati wa kuweka vipengele vyote vya mzunguko, kanuni zifuatazo zinapaswa kuzingatiwa:

1. Panga nafasi ya kila kitengo cha mzunguko wa kazi kulingana na mtiririko wa mzunguko, ili mpangilio uwe rahisi kwa mzunguko wa ishara, na ishara ihifadhiwe katika mwelekeo sawa iwezekanavyo [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. Kwa nyaya zinazofanya kazi kwa mzunguko wa juu, vigezo vya usambazaji kati ya vipengele lazima zizingatiwe. Katika nyaya za jumla, vipengele vinapaswa kupangwa kwa sambamba iwezekanavyo, ambayo si nzuri tu, bali pia ni rahisi kufunga na rahisi kuzalisha kwa wingi.

Jinsi ya kubuni na kukagua mpangilio wa 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. Msimamo wa kubadili piga, kifaa cha upya, mwanga wa kiashiria, nk inafaa, na bar ya kushughulikia haiingilii na vifaa vinavyozunguka.

5. Sura ya nje ya bodi ina radian laini ya 197mil, au imeundwa kulingana na kuchora ukubwa wa muundo.

6. Bodi za kawaida zina kingo za mchakato wa 200mil; pande za kushoto na kulia za ndege ya nyuma zina kingo za mchakato zaidi ya 400mil, na pande za juu na chini zina kingo za mchakato zaidi ya 680mil. Uwekaji wa kifaa haupingani na nafasi ya kufungua dirisha.

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. Lami ya pini ya kifaa, mwelekeo wa kifaa, sauti ya kifaa, maktaba ya kifaa, n.k. ambayo yamechakatwa na soldering ya wimbi huzingatia mahitaji ya soldering ya wimbi.

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. Sehemu za crimping zina zaidi ya mil 120 katika umbali wa uso wa sehemu, na hakuna kifaa katika eneo la sehemu za kukandamiza kwenye uso wa kulehemu.

11. Hakuna vifaa vifupi kati ya vifaa virefu, na hakuna vifaa vya kiraka na vifaa vifupi na vidogo vya kuingilia huwekwa ndani ya 5mm kati ya vifaa vyenye urefu wa zaidi ya 10mm.

12. Vifaa vya polar vina nembo ya silkscreen ya polarity. Maelekezo ya X na Y ya aina sawa ya vipengee vya programu-jalizi ya polarized ni sawa.

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

14. Kuna mshale wa nafasi 3 kwenye uso ulio na vifaa vya SMD, ambavyo vimewekwa kwenye sura ya “L”. Umbali kati ya katikati ya mshale wa kuweka nafasi na makali ya ubao ni kubwa kuliko 240 mils.

15. Ikiwa unahitaji kufanya usindikaji wa bweni, mpangilio unazingatiwa ili kuwezesha usindikaji na mkusanyiko wa bweni na PCB.

16. Mipaka iliyopigwa (kingo zisizo za kawaida) zinapaswa kujazwa kwa njia ya milling grooves na mashimo ya stempu. Shimo la stempu ni utupu usio na metali, kwa ujumla milimita 40 kwa kipenyo na mil 16 kutoka ukingoni.

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. Mpangilio unazingatia njia za busara na laini za kusambaza joto.

4. Capacitor electrolytic inapaswa kutengwa vizuri na kifaa cha juu-joto.

5. Fikiria uharibifu wa joto wa vifaa vya juu vya nguvu na vifaa chini ya gusset.

Tatu, mahitaji ya uadilifu wa ishara ya mpangilio

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. Kasi ya juu na ya chini, digital na analog hupangwa tofauti kulingana na modules.

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.

Nne, mahitaji ya 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. Ili kuepuka kuingiliwa kwa umeme kati ya kifaa kwenye uso wa kulehemu wa bodi moja na bodi moja iliyo karibu, hakuna vifaa nyeti na vifaa vya mionzi yenye nguvu vinapaswa kuwekwa kwenye uso wa kulehemu wa bodi moja.

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. Mzunguko wa ulinzi umewekwa karibu na mzunguko wa interface, kufuata kanuni ya ulinzi wa kwanza na kisha kuchuja.

5. Umbali kutoka kwa mwili unaokinga na ganda linalokinga hadi mwili unaokinga na ganda la kifuniko cha ngao ni zaidi ya mil 500 kwa vifaa vyenye nguvu ya juu ya kusambaza au nyeti hasa (kama vile viosilata vya fuwele, fuwele, n.k.).

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. Wakati safu mbili za ishara ziko moja kwa moja kwa kila mmoja, sheria za wiring za wima lazima zifafanuliwe.

2. Safu kuu ya nguvu iko karibu na safu yake ya ardhi inayofanana iwezekanavyo, na safu ya nguvu hukutana na utawala wa 20H.

3. Each wiring layer has a complete reference plane.

4. Mbao za safu nyingi hutiwa laminated na nyenzo za msingi (CORE) ni linganifu ili kuzuia kupigana kunasababishwa na usambazaji usio sawa wa wiani wa ngozi ya shaba na unene wa asymmetrical wa kati.

5. Unene wa bodi haipaswi kuzidi 4.5mm. Kwa wale walio na unene wa zaidi ya 2.5mm (ndege ya nyuma zaidi ya 3mm), mafundi wanapaswa kuwa wamethibitisha kuwa hakuna tatizo na usindikaji, kuunganisha na vifaa vya PCB, na unene wa bodi ya kadi ya PC ni 1.6mm.

6. Wakati uwiano wa unene-kwa-kipenyo wa via ni mkubwa kuliko 10:1, itathibitishwa na mtengenezaji wa PCB.

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

8. Nguvu na usindikaji wa ardhi wa vipengele muhimu hukutana na mahitaji.

9. Wakati udhibiti wa impedance unahitajika, vigezo vya kuweka safu hukutana na mahitaji.

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. Wakati ubao mmoja unatoa nguvu kwenye ubao mdogo, weka saketi ya kichujio sambamba karibu na kituo cha umeme cha ubao mmoja na mlango wa umeme wa ubao mdogo.

Seven, other requirements

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

2. Rekebisha migao ya pini ya kutengwa, FPGA, EPLD, dereva wa basi na vifaa vingine kulingana na matokeo ya mpangilio ili kuboresha mpangilio.

3. Mpangilio unazingatia ongezeko linalofaa la nafasi kwenye wiring mnene ili kuepuka hali ambayo haiwezi kupitishwa.

4. Ikiwa vifaa maalum, vifaa maalum (kama vile 0.5mmBGA, nk), na taratibu maalum zinapitishwa, muda wa utoaji na usindikaji umezingatiwa kikamilifu, na kuthibitishwa na wazalishaji wa PCB na wafanyakazi wa mchakato.

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. Baada ya mpangilio kukamilika, mchoro wa mkusanyiko wa 1:1 umetolewa kwa wafanyakazi wa mradi ili kuangalia kama uteuzi wa kifurushi cha kifaa ni sahihi dhidi ya huluki ya kifaa.

9. Katika ufunguzi wa dirisha, ndege ya ndani imezingatiwa kuwa imerudishwa, na eneo linalofaa la kukataza wiring limewekwa.