Van prototipe stroombane op broodplanke tot die ontwerp van ons eie printplaat (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 skep die ‘brein’ van hoe toestelle werk. 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). Produkafmetings word gedefinieer tydens die proses van elektroniese ingenieurswese. You can watch a video about it here. 2. PCB -lae – Hoe meer lae, hoe meer kompleks die vervaardiging van PCB is. (Nota: Selfs ‘n enkellaag-PCB kan ‘n komplekse PCB wees, maar hier praat ons oor die kompleksiteit om ‘n PCB te maak. Hoe meer lae ‘n PCB het, hoe duurder is dit om te vervaardig.)

Layer 2 is usually used for simple toy products

Iot verwante produkte het gewoonlik 4 lae

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.

Inligting wat u aan PCB -vervaardigers moet verskaf:

Aantal lae (bv. 2, 4, 6, ens.)

Materiaal (FR-2 (fenoliese katoenpapier), FR-3 (katoenpapier en epoxy), FR-4 (glasvesel en epoxy … ens)

Thickness (0.5 mm, 1.0 mm… ens)

Color (red, black, green… ens)

Oppervlaktebehandeling (ENIG (chemiese onderdompeling van nikkel/goud), DIG (direkte onderdompeling in goud), OSP (organiese soldeerbare preserveermiddels, ens.)

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

Gerber-lêer

PCB design process:

Kringontwerp

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. Ons hou van Quadcept omdat dit geoptimaliseer is vir die ontwerp van PCBS vir vervaardiging (u kan byvoorbeeld ‘n stuk materiaal (BoM) direk vanaf die instrument uitvoer) en op wolk gebaseer is, sodat dit maklik oral gebruik kan word. (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

Frekwensie-toestel

KiCad

Cadence allegro

Voedsel

Rekenaargesteunde ontwerp

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. Die modellêer sal u help om die skema te teken. 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. (Let wel: die besonderhede van die ontwerpproses sal afhang van die gekose sagteware -instrument).

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. You should have selected the components (or are now selecting them), and we describe this process in the EE Design Process video (see video).

Example diagram

‘N Goeie skematika is baie belangrik, aangesien dit tydens die ontfouting as ‘n verwysingsdokument gebruik sal word en ‘n goeie kommunikasiehulpmiddel met ander ingenieurs is. Boonop kan die vervaardiger die toestel toets deur middel van die toetspunte op hierdie dokument.

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. Anders as ‘n skematiese, ken ‘n PCB -uitleg die werklike komponente toe aan presiese liggings op die PCB en toon die snitte wat elke komponent verbind tussen die PCB -lae. 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. Op hierdie manier kan u die geleidende spoor kort hou en geraas en interferensie verminder.

Die gebruikerskoppelvlak (UI) moet ook in gedagte gehou word by die ontwerp van ‘n PCB. Komponente soos klankaansluitings, verbindings, LED’s, ens. Moet aangepas word om die beste gebruikerservaring te verkry.

Once the layout is designed, a Gerber file is generated. U PCBA -vervaardiger sal hierdie lêer gebruik. There are many companies that offer these services, and from HWTrek’s expert library we recommend Kingbrother, NexPCB, and HQPCB.

Sample Gerber files

Die plasing van komponente op die PCB is baie belangrik. Some components can interfere with each other and cause unexpected behavior. As u byvoorbeeld beide Bluetooth- en Wi-Fi-modules het, het hulle dieselfde bandwydte van 2.4 GHz en kan dit met mekaar inmeng as dit verkeerd geplaas word.

PCB produksie

When you send the Gerber file to the PCB manufacturer, they can print the board. Dit sal die basis wees om die grondslag te bou vir die toevoeging van komponente aan die PCB en die vervaardiging van die PCBA (printboard assemblage).

Unassembled PCBS

PCBA (Assembly)

Materiële voorbereiding

Op hierdie punt in u EE -ontwerp moes u die komponente gekies het. You can ask the PCBA manufacturer to order the required components for you, or do it yourself if you choose a supplier. Sake wat aandag benodig:

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.

Minimum bestelhoeveelheid: kontroleer die minimum bestelhoeveelheid van die komponent. As u minder as die minimum koop, moet u seker maak dat die geselekteerde komponente in voorraad is. For small batches (up to 50), you can order online from DigiKey or Mouser. Raadpleeg u vervaardiger vir meer hoeveelhede.

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 (oppervlaktemonteringstegnologie) is die mees gebruikte metode vir massaproduksie. It is done by fast, accurate SMT machines that save you time, money and avoid human error.

Dinge om te onthou:

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.

Hervloei soldeer

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.

The trickiest part here is not to overheat or damage the components, because the thermal characteristics of each package are different. ‘N Betroubare PCBA -vervaardiger is verantwoordelik vir hierdie proses, en u hoef slegs die spesifikasies van die komponente te voorsien.

Terugvloei proses.

Ander sweismetodes:

Wave soldering is mainly used for manually added components by the through-hole method. In this case, your PCBA will first go through the reflow welding furnace, and then manually add other components after it will go through the wave soldering machine.

Ysterlas kan vir spesifieke situasies gebruik word, maar nie vir massaproduksie nie.

Toetsing en kwaliteitsinspeksie

In hierdie stap word PCBA -monsters getoets om kwaliteit te verseker. Algemene foute is: kortsluitings in onderdele wat ontkoppel is, komponente wat nie in lyn is nie en dele van die stroombaan wat nie verbind moet word nie. Die mees algemene toetse:

IKT (Aanlyn toetsing). When designing a PCB, some test points are usually reserved for debugging, programming, and other purposes. Die ICT -masjien gebruik hierdie toetspunte vir oop-/kortsluitingstoetse en kyk of die waardes van die passiewe komponente (weerstande, induktors, kapasitors) binne die spesifikasiebereik is.

AOI (outomatiese optiese inspeksie). Manufacturers use a “gold sample” (reference PCBA) to compare with other samples. Vir hierdie toets moet die vervaardiger van die hardeware spesifikasies en toleransies aan die vervaardiger verskaf om die parameters te stel.

X -straal. The PCBA manufacturer will use X-rays to check the welding conditions of the BGA (ball Grid Array) components. Kyk na die X-straaltoets in hierdie video.