Od prototipnih vezij na ploščah za kruh do oblikovanja lastnih tiskano vezje (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 ustvarja “možgane” delovanja naprav. 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). Dimenzije izdelka so določene med postopkom oblikovanja elektronskega inženiringa. Video o tem si lahko ogledate tukaj. 2. Plasti PCB – Več slojev, bolj zapletena je IZDELAVA PCB. (Opomba: Tudi enoslojna PCB je lahko zapletena PCB, vendar tukaj govorimo o zapletenosti izdelave PCB. Več plasti kot ima PCB, dražja je izdelava.)

Layer 2 is usually used for simple toy products

Iot sorodni izdelki imajo običajno 4 plasti

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.

Informacije, ki jih morate posredovati proizvajalcem PCB:

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

Materiali (FR-2 (fenolni bombažni papir), FR-3 (bombažni papir in epoksi), FR-4 (steklena vlakna in epoksi… Etc.)

Thickness (0.5 mm, 1.0 mm… Etc.)

Color (red, black, green… Etc.)

Površinska obdelava (ENIG (potopitev v kemično nikelj/zlato), DIG (neposredno potapljanje v zlato), OSP (organski spajkalni konzervansi itd.)

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

Datoteka Gerber

PCB design process:

Zasnova vezja

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

Frekvenčna naprava

KiCad

Cadence allegro

mat

Računalniško podprto oblikovanje

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. Datoteka modela vam bo pomagala narisati shemo. 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. (Opomba: podrobnosti procesa oblikovanja bodo odvisne od izbranega programskega orodja).

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. Morali bi izbrati komponente (ali jih zdaj izbirate), ta postopek pa opisujemo v videu EE Design Process (glej 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. Poleg tega lahko proizvajalec napravo preskusi s preskusnimi točkami v tem dokumentu.

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. Za razliko od sheme, postavitev tiskanega vezja dodeljuje dejanske komponente natančnim lokacijam na tiskanem vezju in prikazuje sledi, ki povezujejo vsako komponento skupaj med plastmi tiskanega vezja. 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. Na ta način lahko ohranite prevodnost kratko in zmanjšate hrup in motnje.

Pri načrtovanju tiskanega vezja je treba upoštevati tudi uporabniški vmesnik (UI). Komponente, kot so avdio priključki, priključki, LED diode itd., Je treba prilagoditi, da dosežete najboljšo uporabniško izkušnjo.

Once the layout is designed, a Gerber file is generated. Proizvajalec PCBA bo uporabil to datoteko. There are many companies that offer these services, and from HWTrek’s expert library we recommend Kingbrother, NexPCB, and HQPCB.

Sample Gerber files

Postavitev komponent na tiskano vezje je zelo pomembna. 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. To bo podlaga za nadaljnjo izgradnjo temeljev za dodajanje komponent na tiskano vezje in izdelavo tiskanega vezja (PCBA).

Unassembled PCBS

PCBA (Assembly)

Priprava materiala

Na tej točki v zasnovi EE bi morali izbrati komponente. You can ask the PCBA manufacturer to order the required components for you, or do it yourself if you choose a supplier. Zadeve, ki jih je treba posvetiti:

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.

Najmanjša količina naročila: Preverite najmanjšo količino naročila komponente. Če kupite manj kot minimalno vrednost, se prepričajte, da so izbrane komponente na zalogi. For small batches (up to 50), you can order online from DigiKey or Mouser. Za več količin se obrnite na proizvajalca.

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 (tehnologija površinske montaže) je najbolj razširjena metoda v množični proizvodnji. It is done by fast, accurate SMT machines that save you time, money and avoid human error.

Stvari, ki jih je treba zapomniti:

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.

Reflow soldering

Spajkanje s ponovnim polnjenjem je postopek, s katerim se komponente “prilepijo” na tiskano vezje. 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.

The trickiest part here is not to overheat or damage the components, because the thermal characteristics of each package are different. Za ta proces bo odgovoren zanesljiv proizvajalec PCBA, ki mu morate le zagotoviti specifikacije komponent.

Postopek refluksa.

Drugi načini varjenja:

Spajkanje valov se uporablja predvsem za ročno dodane komponente po metodi skozi luknje. V tem primeru bo vaš PCBA najprej šel skozi varilno peč z reflowom, nato pa bo ročno dodal druge komponente, potem ko bo šel skozi stroj za spajkanje valov.

Varjenje železa se lahko uporablja za posebne situacije, ne pa tudi za množično proizvodnjo.

Testiranje in pregled kakovosti

V tem koraku se vzorci PCBA testirajo, da se zagotovi kakovost. Pogoste napake so: kratek stik v odklopljenih komponentah, nepravilno razporejene komponente in deli vezja, ki jih ne smete priključiti. Najpogostejši testi:

IKT (spletno testiranje). When designing a PCB, some test points are usually reserved for debugging, programming, and other purposes. Stroj IKT bo te preskusne točke uporabil za preskušanje odprtega/kratkega stika in preveril, ali so vrednosti pasivnih komponent (upori, induktorji, kondenzatorji) v območju specifikacij.

AOI (avtomatski optični pregled). Manufacturers use a “gold sample” (reference PCBA) to compare with other samples. Za ta preskus bo ustvarjalec strojne opreme proizvajalcu zagotovil specifikacije in tolerance za nastavitev parametrov.

Rentgen. The PCBA manufacturer will use X-rays to check the welding conditions of the BGA (ball Grid Array) components. V tem videu si oglejte rentgenski test.