Kutoka kwa mizunguko ya mfano kwenye bodi za mkate hadi kubuni yetu wenyewe printed mzunguko bodi (PCBS), it was like getting off the training wheels. There’s a lot to learn about this process, so let’s get started. PCB design is carried out in an electrical engineering (EE) process. EE inaunda “ubongo” wa jinsi vifaa hufanya kazi. Without electronics, you’re left with little more than a pile of metal and plastic.

Things to know before starting PCB design: 1. PCB size – this depends on your product size (or case size). Vipimo vya bidhaa hufafanuliwa wakati wa mchakato wa muundo wa uhandisi wa elektroniki. You can watch a video about it here. 2. Tabaka za PCB – Tabaka zaidi, ngumu zaidi Utengenezaji wa PCB. (Kumbuka: Hata PCB ya safu moja inaweza kuwa PCB ngumu, lakini hapa tunazungumzia ugumu wa kutengeneza PCB. Tabaka zaidi ambazo PCB ina, ni ghali zaidi kutengeneza.)

Layer 2 is usually used for simple toy products

Bidhaa zinazohusiana na Iot kawaida huwa na tabaka 4

Typically used for floors 6 to 8 of a smartphone or smartwatch.

3. Your PCB manufacturer’s requirements. Be sure to read the guidelines for rhythm, trace size, power isolation, and file naming before you start designing.

Habari unayohitaji kutoa kwa watengenezaji wa PCB:

Number of layers (e.g. 2, 4, 6, etc.)

Vifaa (FR-2 (karatasi ya pamba ya phenolic), FR-3 (karatasi ya pamba na epoxy), FR-4 (nyuzi za glasi na epoxy… Na kadhalika.)

Unene (0.5 mm, 1.0 mm… Na kadhalika.)

Color (red, black, green… Na kadhalika.)

Matibabu ya uso (ENIG (nikeli ya kemikali / kuzamishwa kwa dhahabu), DIG (kuzamishwa kwa dhahabu moja kwa moja), OSP (vihifadhi vya kuuza kikaboni, n.k.)

Copper weight (1 oz (35 microns), 2 oz (70 microns), 0.5 oz (18 microns)… Na kadhalika.)

Faili ya Gerber

PCB design process:

Ubunifu wa mzunguko

For this step, you need to create the schematic. This is a document, like a blueprint, that describes how components relate to each other and work together. To create the schematic file, you will need a software tool. We like Quadcept because it is optimized for designing PCBS for manufacturing (for example, you can export a Bill of Material (BoM) directly from the tool) and is cloud-based, so it can be easily used anywhere. (They also offer a free community version of the tool for manufacturers and students.)

There are many other options you can choose from:

Altium

ExpressPCB

Kifaa cha masafa

KiCad

Cadence allegro

Chakula

Ubunifu uliosaidiwa na kompyuta

DipTrace

After you install the selected tools, you need to obtain the component specifications for each selected component. They can often be found on the supplier’s website. Faili ya mfano itakusaidia kuteka skimu. This component becomes available in the database when you upload the model to the software tool. Then, all you have to do is follow the data manual and connect the wire to each pin in the component. (Kumbuka: maelezo ya mchakato wa kubuni yatategemea zana ya programu iliyochaguliwa).

Each schematic symbol needs to have an associated PCB space area to define the physical dimensions of the component and the location of the through holes on the brazing pad or PCB. Unapaswa kuwa umechagua vifaa (au sasa unavichagua), na tunaelezea mchakato huu katika video ya Mchakato wa Ubunifu wa EE (angalia video).

Example diagram

A good schematic is really important, as it will be used as a reference document during debugging and is a good communication tool with other engineers. Kwa kuongeza, mtengenezaji anaweza kujaribu kifaa kupitia vidokezo vya jaribio kwenye hati hii.

PCB layout + Gerber file

To design the PCB layout and create Gerber files, you can use the same software tools we mentioned in circuit design. Tofauti na mpango, mpangilio wa PCB unapeana vifaa halisi kwa maeneo halisi kwenye PCB na inaonyesha nyimbo zinazounganisha kila sehemu pamoja kati ya tabaka za PCB. As mentioned at the beginning of this article, the more layers, the more complex the manufacturing required, and the higher the cost.

Divide the PCB into logical parts based on functions (e.g. power supply, audio output, etc.). Then, be sure to group the components of each section into the same area. Kwa njia hii, unaweza kuweka athari ya conductive fupi na kupunguza kelele na kuingiliwa.

Kiolesura cha mtumiaji (UI) pia inahitaji kuzingatiwa wakati wa kubuni PCB. Vipengele kama vile vinjari vya sauti, viunganishi, viongo, n.k zinahitaji kurekebishwa ili kufikia uzoefu bora wa mtumiaji.

Once the layout is designed, a Gerber file is generated. Mtengenezaji wako wa PCBA atatumia faili hii. There are many companies that offer these services, and from HWTrek’s expert library we recommend Kingbrother, NexPCB, and HQPCB.

Sample Gerber files

Uwekaji wa vifaa kwenye PCB ni muhimu sana. Some components can interfere with each other and cause unexpected behavior. For example, if you have both Bluetooth and Wi-Fi modules, they have the same 2.4ghz bandwidth and can interfere with each other if incorrectly placed.

PCB production

When you send the Gerber file to the PCB manufacturer, they can print the board. Hii itakuwa msingi wa kujenga zaidi msingi wa kuongeza vifaa kwenye PCB na kutengeneza PCBA (mkutano wa bodi ya mzunguko iliyochapishwa).

Unassembled PCBS

PCBA (Assembly)

Matayarisho ya nyenzo

Kwa wakati huu katika muundo wako wa EE, unapaswa kuwa umechagua vifaa. You can ask the PCBA manufacturer to order the required components for you, or do it yourself if you choose a supplier. Mambo yanayohitaji umakini:

Lead time: As these components come from different suppliers, keep the lead time in mind. For some components, it can take up to 8-16 weeks.

Packaging: Order components from reels that are automatically picked up by SMT machines instead of packaging them individually.

Kiwango cha chini cha utaratibu: Angalia kiwango cha chini cha mpangilio wa sehemu hiyo. Ukinunua chini ya kiwango cha chini, hakikisha vifaa vilivyochaguliwa viko katika hisa. For small batches (up to 50), you can order online from DigiKey or Mouser. Kwa idadi zaidi, tafadhali tafuta ushauri kutoka kwa mtengenezaji wako.

Loss: Order 10% more to cover loss (not for expensive components)

Install components on the PCB

There are two main ways to place components on a PCB surface:

Through-holes (through-holes) are manual methods of assembling assemblies with wires into holes on the surface of a PCB. It is also commonly known as DIP or dual in-line packaging process. (See SMT in progress in this video)

SMT (teknolojia ya juu ya mlima) ndiyo njia inayotumika sana katika uzalishaji wa wingi. It is done by fast, accurate SMT machines that save you time, money and avoid human error.

Mambo ya kukumbuka:

Your component type number must not exceed the number of reels that the manufacturer’s SMT machine can support.

Optimize and consolidate your components so that only one SMT runs.

Check manufacturer supported footprint pad sizes. Otherwise, the SMT machine will not install components correctly.

Some larger components cannot be installed by machine and still require manual through-hole work. Therefore, both technologies can be used on the same board.

Any components you need to manually add via the through-hole method add to the manufacturing cost.

Kutengenezea kutengenezea

Reflow soldering is the process of making components “stick” to the PCB. The PCBA heats the circuit board through a reflow furnace or an infrared lamp until the solder melts, thereby permanently attaching the component to the circuit board.

Sehemu ngumu zaidi hapa sio kuzidisha joto au kuharibu vifaa, kwa sababu sifa za joto za kila kifurushi ni tofauti. Mtengenezaji wa PCBA anayeaminika atawajibika kwa mchakato huu, na unachohitaji kufanya ni kuwapa uainishaji wa sehemu.

Mchakato wa Reflux.

Other welding methods:

Wave soldering is mainly used for manually added components by the through-hole method. Katika kesi hii, PCBA yako itapitia tanuru ya kulehemu tena, na kisha uongeze vifaa vingine kwa mikono baada ya kupitia mashine ya kutengenezea mawimbi.

Ulehemu wa chuma unaweza kutumika kwa hali maalum, lakini sio kwa uzalishaji wa wingi.

Upimaji na ukaguzi wa ubora

Katika hatua hii, sampuli za PCBA zinajaribiwa ili kuhakikisha ubora. Makosa ya kawaida ni: mizunguko fupi katika vifaa vilivyokatizwa, vifaa visivyobadilishwa na sehemu za mzunguko ambazo hazipaswi kuunganishwa. Vipimo vya kawaida:

ICT (Upimaji mkondoni). When designing a PCB, some test points are usually reserved for debugging, programming, and other purposes. Mashine ya ICT itatumia alama hizi za upimaji kwa upimaji wa mzunguko wazi / fupi na uangalie kwamba maadili ya vifaa vya upendeleo (vipingaji, inductors, capacitors) viko ndani ya anuwai ya vipimo.

AOI (ukaguzi wa macho otomatiki). Manufacturers use a “gold sample” (reference PCBA) to compare with other samples. Kwa jaribio hili, muundaji wa vifaa atahitaji kutoa uainishaji na uvumilivu kwa mtengenezaji ili kuweka vigezo.

X ray. The PCBA manufacturer will use X-rays to check the welding conditions of the BGA (ball Grid Array) components. Tazama jaribio la X-ray kwenye video hii.