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.

Ushbu maqola birinchi navbatda PCB tartibini loyihalash qoidalari va usullarini tanishtiradi, so’ngra sxemaning DFM talablari, termal dizayn talablari, signalning yaxlitligi talablari, EMC talablari, qatlam sozlamalari va quvvatni yerga taqsimlash talablaridan boshlab tenglikni sxemasini loyihalash va tekshirishni tushuntiradi. quvvat modullari. Talablar va boshqa jihatlar batafsil tahlil qilinadi va tafsilotlarni bilish uchun muharrirni kuzatib boring.

PCB tartibini loyihalash qoidalari

1. Oddiy sharoitlarda barcha komponentlar elektron plataning bir xil yuzasiga joylashtirilishi kerak. Faqat yuqori darajadagi komponentlar juda zich bo’lganda, cheklangan balandlik va past issiqlik ishlab chiqarishga ega bo’lgan ba’zi qurilmalar, masalan, chip rezistorlari, chip kondensatorlari va chip kondansatkichlari o’rnatilishi mumkin. Chip IC va boshqalar pastki qatlamga joylashtiriladi.

2. Elektr ish faoliyatini ta’minlash sharti ostida, toza va chiroyli bo’lishi uchun komponentlar panjara ustiga joylashtirilishi va bir-biriga parallel yoki perpendikulyar joylashtirilishi kerak. Oddiy sharoitlarda komponentlarning bir-birining ustiga chiqishiga yo’l qo’yilmaydi; komponentlarning joylashishi ixcham bo’lishi kerak va komponentlar butun sxema bo’yicha joylashtirilishi kerak. Tarqatish bir xil va zich.

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

4. Elektron plataning chetidan masofa odatda 2MM dan kam emas. Elektron plataning eng yaxshi shakli to’rtburchaklar, tomonlar nisbati esa 3:2 yoki 4:3. Elektron plataning o’lchami 200 mm dan 150 mm dan katta bo’lsa, elektron plataning mexanik kuchga bardosh berishi mumkinligini ko’rib chiqing.

PCB layout design skills

PCB ning sxemasini loyihalashda elektron plataning birliklari tahlil qilinishi kerak va tartib dizayni boshlang’ich funktsiyasiga asoslangan bo’lishi kerak. Sxemaning barcha tarkibiy qismlarini yotqizishda quyidagi printsiplarga rioya qilish kerak:

1. Har bir funksional sxema blokining joylashuvini sxema oqimiga ko‘ra tartibga soling, shunda sxema signal aylanishi uchun qulay bo‘lsin va signal imkon qadar bir xil yo‘nalishda saqlanadi [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. Yuqori chastotalarda ishlaydigan sxemalar uchun komponentlar orasidagi taqsimot parametrlarini hisobga olish kerak. Umumiy sxemalarda komponentlar iloji boricha parallel ravishda joylashtirilishi kerak, bu nafaqat chiroyli, balki o’rnatish oson va ommaviy ishlab chiqarish oson.

PCB tartibini qanday loyihalash va tekshirish kerak

1. DFM requirements for layout

1. Texnologik jarayonning optimal marshruti belgilandi, barcha qurilmalar doskaga joylashtirildi.

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. Terish tugmasi, qayta o’rnatish moslamasi, indikator chirog’i va boshqalarning holati mos keladi va tutqich paneli atrofdagi qurilmalarga to’sqinlik qilmaydi.

5. Kengashning tashqi ramkasi 197mil silliq radianga ega yoki strukturaviy o’lchamdagi chizmaga muvofiq ishlab chiqilgan.

6. Oddiy taxtalar 200milli texnologik qirralarga ega; orqa panelning chap va o’ng tomonlari 400mil dan ortiq texnologik qirralarga ega va yuqori va pastki tomonlari 680mil dan katta texnologik qirralarga ega. Qurilmaning joylashishi oynani ochish holatiga zid kelmaydi.

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. To’lqinli lehim bilan ishlov berilgan qurilma pinining balandligi, qurilma yo’nalishi, qurilma qadami, qurilma kutubxonasi va boshqalar to’lqinli lehimlash talablarini hisobga oladi.

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. Siqish qismlari komponent sirt masofasida 120 mildan ortiq masofaga ega va payvandlash yuzasida siqish qismlarining o’tish joyida hech qanday qurilma yo’q.

11. Uzun bo’yli qurilmalar o’rtasida qisqa qurilmalar mavjud emas, shuningdek, balandligi 5 mm dan ortiq bo’lgan qurilmalar o’rtasida 10 mm masofada yamoq moslamalari va qisqa va kichik o’rnatish moslamalari joylashtirilmaydi.

12. Polar qurilmalar polaritli silkscreen logotiplariga ega. Xuddi shu turdagi polarizatsiyalangan plagin komponentlarining X va Y yo’nalishlari bir xil.

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

14. SMD qurilmalari joylashgan sirtda 3 ta joylashish kursorlari mavjud bo’lib, ular “L” shaklida joylashtirilgan. Joylashuv kursorining markazi va taxtaning cheti orasidagi masofa 240 milyadan kattaroqdir.

15. Agar siz taxta ishlov berishni amalga oshirishingiz kerak bo’lsa, joylashtirish va tenglikni qayta ishlash va yig’ishni osonlashtirish uchun sxema hisoblanadi.

16. Yong’oqlangan qirralarning (g’ayritabiiy qirralarning) frezalash oluklari va shtamp teshiklari yordamida to’ldirilishi kerak. Shtamp teshigi metalllashtirilmagan bo’shliq bo’lib, odatda diametri 40 milya va chetidan 16 milya.

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

Ikkinchidan, tartibning termal dizayn talablari

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. Tartibi oqilona va silliq issiqlik tarqalish kanallarini hisobga oladi.

4. Elektrolitik kondansatör yuqori issiqlik moslamasidan to’g’ri ajratilishi kerak.

5. Gusset ostidagi yuqori quvvatli qurilmalar va qurilmalarning issiqlik tarqalishini ko’rib chiqing.

Uchinchidan, tartibning signal yaxlitligi talablari

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. Yuqori tezlikda va past tezlikda, raqamli va analog modullarga ko’ra alohida joylashtirilgan.

5. Tizim talablari bajarilishini ta’minlash uchun tahlil va simulyatsiya natijalari yoki mavjud tajriba asosida avtobusning topologik tuzilishini aniqlang.

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.

To’rtinchidan, EMC talablari

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. Yagona taxtaning payvandlash yuzasida va ulashgan bitta taxtali qurilma o’rtasida elektromagnit shovqinlarni oldini olish uchun bitta taxtaning payvandlash yuzasiga hech qanday sezgir asboblar va kuchli nurlanish moslamalari joylashtirilmasligi kerak.

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. Himoya sxemasi interfeys sxemasi yaqinida, birinchi himoya qilish va keyin filtrlash tamoyiliga rioya qilgan holda joylashtiriladi.

5. Yuqori uzatish quvvatiga ega yoki ayniqsa sezgir (masalan, kristall osilatorlar, kristallar va boshqalar) qurilmalar uchun ekranlash korpusi va himoya qiluvchi qobiqdan himoya korpusi va ekran qoplamasi qobig’igacha bo’lgan masofa 500 mildan ortiq.

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. Ikkita signal qatlami to’g’ridan-to’g’ri bir-biriga ulashganda, vertikal simlarni ulash qoidalari aniqlanishi kerak.

2. Asosiy quvvat qatlami iloji boricha uning mos keladigan tuproq qatlamiga ulashgan va quvvat qatlami 20H qoidasiga javob beradi.

3. Each wiring layer has a complete reference plane.

4. Ko’p qatlamli taxtalar laminatlangan va yadro materiali (CORE) mis teri zichligi va muhitning assimetrik qalinligining notekis taqsimlanishidan kelib chiqadigan burilishning oldini olish uchun nosimmetrikdir.

5. Kengashning qalinligi 4.5 mm dan oshmasligi kerak. Qalinligi 2.5 mm dan ortiq (orqa paneli 3 mm dan katta) bo’lganlar uchun texniklar tenglikni qayta ishlash, yig’ish va jihozlashda hech qanday muammo yo’qligini va kompyuter kartasi qalinligi 1.6 mm ekanligini tasdiqlashlari kerak.

6. Qachonki, qalinligi diametrga nisbati 10:1 dan katta bo’lsa, u PCB ishlab chiqaruvchisi tomonidan tasdiqlanadi.

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

8. Asosiy komponentlarning quvvati va erga ishlov berish talablarga javob beradi.

9. Empedans nazorati zarur bo’lganda, qatlam sozlamalari parametrlari talablarga javob beradi.

Six, power module requirements

1. Elektr ta’minoti qismining joylashuvi kirish va chiqish liniyalarining silliq bo’lishini va kesishmasligini ta’minlaydi.

2. Yagona plata pastki panelni quvvat bilan ta’minlaganida, mos keladigan filtr sxemasini bitta plataning quvvat manbaiga va pastki panelning quvvat manbaiga yaqin joyga qo’ying.

Etti, boshqa talablar

1. Tartib simlarning umumiy silliqligini hisobga oladi va asosiy ma’lumotlar oqimi oqilona.

2. Tartibni optimallashtirish uchun istisno, FPGA, EPLD, avtobus drayveri va boshqa qurilmalarning pin belgilashlarini tartib natijalariga ko’ra sozlang.

3. Tartib, uni yo’naltirish mumkin bo’lmagan vaziyatni oldini olish uchun zich o’tkazgichlarda bo’sh joyni mos ravishda oshirishni hisobga oladi.

4. Agar maxsus materiallar, maxsus qurilmalar (masalan, 0.5 mmBGA va boshqalar) va maxsus jarayonlar qabul qilingan bo’lsa, etkazib berish muddati va qayta ishlanishi to’liq ko’rib chiqilgan va PCB ishlab chiqaruvchilari va texnologik xodimlar tomonidan tasdiqlangan.

5. Gusset konnektorining yo’nalishi va yo’nalishini teskari o’zgartirishga yo’l qo’ymaslik uchun pinning mos keladigan aloqasi tasdiqlangan.

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. Joylashtirish tugallangandan so’ng, loyiha xodimlariga qurilma to’plamini tanlash qurilma ob’ektiga nisbatan to’g’ri yoki yo’qligini tekshirish uchun 1: 1 yig’ish chizmasi taqdim etildi.

9. Oynaning ochilishida ichki tekislik orqaga tortilgan deb hisoblangan va tegishli simlarni taqiqlash maydoni o’rnatilgan.