As an essential part of electronic products, an lèt detache sikwi tablo (PCB) plays a key role in realizing the function of electronic products, which leads to the increasingly prominent importance of PCB design, because the performance of PCB design directly determines the function and cost of electronic products. Bon konsepsyon PCB ka kenbe pwodwi elektwonik nan anpil pwoblèm, konsa asire ke pwodwi yo ka fèt san pwoblèm manifaktire ak satisfè tout bezwen yo nan aplikasyon pratik.

Nan tout eleman ki kontribye nan konsepsyon PCB, Design fabrikasyon (DFM) se absoliman esansyèl paske li lye konsepsyon PCB ak fabrikasyon PCB yo nan lòd yo jwenn pwoblèm bonè epi rezoud yo nan tan pandan tout sik lavi a nan pwodwi elektwonik. One myth is that the complexity of PCB design will increase as manufacturability of electronics is considered at the PCB design stage. In the design life cycle of electronic products, DFM can not only make electronic products participate in automatic production smoothly, and save labor costs in the manufacturing process, but also effectively shorten the manufacturing time to ensure the timely completion of the final electronic products.

PCB fabrikabilite

Lè yo konbine fabrikabilite ak konsepsyon PCB, konsepsyon fabrikasyon se yon faktè kle ki mennen nan manifakti efikas, kalite siperyè ak pri ki ba. The research of PCB manufacturability covers a wide range, usually divided into PCB manufacturing and PCB assembly.

LPCB production

For PCB manufacturing, the following aspects should be considered: PCB size, PCB shape, process edge and Mark point. Si aspè sa yo pa konplètman pran an kont nan etap nan konsepsyon PCB, otomatik chip machin laminasyon ka pa kapab aksepte ankadreman PCB prefabrike sof si mezi pwosesis adisyonèl yo te pran. Pou fè zafè yo vin pi mal, kèk plak pa ka fè otomatikman lè l sèvi avèk manyèl soude. As a result, the manufacturing cycle will be longer and labor costs will increase.

1. PCB size

Chak enstale chip gen pwòp gwosè PCB li vle, ki varye selon paramèt chak enstale. Pou egzanp, enstale chip la aksepte yon gwosè PCB maksimòm de 500mm * 450mm ak yon gwosè PCB minimòm de 30mm * 30mm. Sa pa vle di ke nou pa ka okipe konpozan tablo PCB ki pi piti pase 30mm pa 30mm, epi yo ka konte sou tablo tèt lè pi piti gwosè yo mande yo. Lè ou ka sèlman konte sou enstalasyon manyèl ak depans travay yo ap monte ak sik pwodiksyon yo soti nan kontwòl, chip machin SMT pa janm ap aksepte tablo PCB ki twò gwo oswa twò piti. Therefore, in the PCB design stage, the PCB size requirements set by automatic installation and manufacturing must be fully considered, and it must be controlled within the effective range.

Figi sa a montre dokiman konsepsyon tablo PCB ki konplete pa lojisyèl Huaqiu DFM. As a 5×2 board, each square unit is a single piece, measuring 50mm by 20mm. The connection between each unit is achieved by V-cut/V-scoring technology. In this image, the entire square is shown with a final size of 100mm by 100mm. Dapre kondisyon ki anwo yo, li ka konkli ke gwosè tablo a nan limit ki akseptab la.

2. PCB shape

In addition to PCB size, all chip SMT machines have requirements for PCB shape. Yon PCB nòmal yo ta dwe rektangilè nan fòm ak yon rapò longè ak lajè 4: 3 oswa 5: 4 (pi bon). If the PCB is irregularly shaped, additional measures must be taken prior to SMT assembly, resulting in increased costs. Pou anpeche sa rive, PCB a dwe fèt nan yon fòm komen pandan faz konsepsyon PCB la pou satisfè kondisyon SMT yo. Sepandan, sa a difisil a fè nan pratik. Lè fòm kèk pwodwi elektwonik dwe iregilye, yo dwe itilize twou koupon pou bay PCB final la yon fòm nòmal. Lè yo reyini, redondants bafl oksilyè yo ka retire nan PCB la pou satisfè enstalasyon otomatik ak kondisyon espas.

Foto ki anba a montre PCB la ak fòm iregilye, ak kwen pwosesis la te ajoute pa lojisyèl Huaqiu DFM. The whole circuit board size is 80mm * 52mm, and the square area is the size of the actual PCB. The size of the upper right corner area is 40mm by 20mm, which is the auxiliary craft edge produced by the bridge of the stamp hole.

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3. Pwosesis bò

To meet the requirements of automatic manufacturing, process edges must be placed on the PCB to secure the PCB.

In PCB design stage, 5mm wide process edge should be set aside in advance, without leaving any components and wiring. Gid teknik la anjeneral mete sou bò kout PCB la, men ka bò kout la chwazi lè rapò aspè a depase 80%. Apre asanble, yo ka retire kwen pwosesis la kòm yon wòl pwodiksyon oksilyè.

4. Mark point

For PCBS with components installed, Mark points should be added as a common reference point to ensure that component locations are accurately determined for each assembly device. Therefore, Mark points are SMT manufacturing benchmarks required for automated manufacturing.

Components require 2 Mark points and PCBS require 3 Mark points. These marks should be placed on the edges of the PCB board and cover all SMT components. Distans sant ant pwen Mak ak kwen plak la ta dwe omwen 5mm. For PCBS with double-sided SMT components, Mark points should be placed on both sides. If the components are too close together to place Mark points on the board, they can be placed on the edge of the process.

LPCB assembly

PCB assembly, or PCBA for short, is actually the process of welding components onto bare boards. Yo nan lòd yo satisfè kondisyon ki nan manifakti otomatik, asanble PCB gen kèk kondisyon pou pake asanble ak Layout asanble.

1. Anbalaj nan eleman

Pandan konsepsyon PCBA, si pakè eleman yo pa satisfè estanda apwopriye yo ak konpozan yo twò pre ansanm, enstalasyon otomatik pa pral rive.

Yo nan lòd yo jwenn pi bon anbalaj la eleman, yo ta dwe itilize pwofesyonèl lojisyèl konsepsyon EDA konfòme li avèk estanda entènasyonal anbalaj eleman. During PCB design, the aerial view area must not overlap with other areas, and the automatic IC SMT machine will be able to accurately identify and mount the surface.

2. Component layout

Layout eleman se yon travay enpòtan nan konsepsyon PCB paske pèfòmans li dirèkteman gen rapò ak konpleksite nan aparans PCB ak pwosesis fabrikasyon.

Pandan Layout eleman yo, yo ta dwe detèmine sifas asanble SMD ak THD konpozan yo. Isit la, nou mete devan PCB la kòm eleman yon bò ak do a kòm bò eleman B. The assembly layout should consider the assembly form, including single layer single package assembly, double layer single package assembly, single layer mixed package assembly, Side A mixed package and side B single package assembly and side A THD and side B SMD assembly. Asanble diferan mande pou pwosesis fabrikasyon diferan ak teknik. Therefore, in terms of component layout, the best component layout should be selected to make manufacturing simple and easy, so as to improve the manufacturing efficiency of the whole process.

In addition, consideration must be given to the orientation of component layout, spacing between components, heat dissipation, and component height.

In general, component orientation should be consistent. Components are laid out in accordance with the principle of minimum tracking distance, based on which components with polarity markers should have uniform polarity directions, and components without polarity markers should be neatly aligned along the X or Y axis. Wotè eleman an ta dwe jiska 4mm, ak direksyon transmisyon ant eleman an ak PCB la ta dwe 90 °.

To improve the welding speed of components and facilitate subsequent inspection, the spacing between components should be consistent. Components in the same network should be close to each other and a safe distance should be left between different networks according to the voltage drop. Silkscreen and pad must not overlap, otherwise components will not be installed.

Due to the actual operating temperature of the PCB and the thermal characteristics of the electrical components, heat dissipation should be considered. Layout nan eleman yo ta dwe konsantre sou dissipation chalè. Si sa nesesè, sèvi ak yon fanatik oswa koule chalè. Radyatè ki apwopriye yo ta dwe chwazi pou eleman yo pouvwa ak eleman sansib chalè yo ta dwe mete lwen chalè. The high component should be placed after the low component.

More details should be focused on PCB DFM, and experience should be accumulated in practice. Pou egzanp, segondè-vitès siyal kondisyon konsepsyon PCB gen kondisyon enpedans espesyal epi yo ta dwe diskite avèk manifakti a tablo anvan fabrike aktyèl detèmine enpedans ak enfòmasyon kouch. Yo nan lòd yo prepare pou pwodiksyon sou tablo PCB ti gwosè ak fil elektrik dans, yo ta dwe lajè a fil elektrik minimòm ak nan-twou kapasite dyamèt fabrikasyon dwe diskite avèk manifakti a PCB asire pwodiksyon lis nan PCBS sa yo.