Vum Prototyp Circuiten op Broutplaten bis zum Design vun eisen eegenen gedréckt Circuit Verwaltungsrot (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 gëtt an engem Elektrotechnik (EE) Prozess duerchgefouert. EE kreéiert de “Gehir” vu wéi Apparater funktionnéieren. 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). Produktdimensioune ginn definéiert wärend dem elektroneschen Ingenieursdesignprozess. You can watch a video about it here. 2. PCB Schichten – Déi méi Schichten, wat méi komplex MANUFACTURE vu PCB ass. (Bemierkung: Och eng eenzeg Schicht PCB kann e komplexe PCB sinn, awer hei schwätze mir iwwer d’Komplexitéit fir e PCB ze maachen. Wat méi Schichten e PCB huet, wat méi deier ass et ze fabrizéieren.)

Layer 2 is usually used for simple toy products

Iot verwandte Produkter hunn normalerweis 4 Schichten

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.

Informatioun déi Dir braucht fir PCB Hiersteller ze liwweren:

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

Materialien (FR-2 (phenolesche Kotengpabeier), FR-3 (Kotengpabeier an Epoxy), FR-4 (Glasfaser an Epoxy … Etc.)

Déck (0.5 mm, 1.0 mm … Etc.)

Color (red, black, green… Etc.)

Uewerflächebehandlung (ENIG (chemesch Néckel/Gold Taucht), DIG (direkt Gold Taucht), OSP (organesch solderbar Konservéierungsmëttel, asw.)

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

Gerber Dossier

PCB design process:

Circuit Design

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

Frequenz Apparat

KiCad

Cadence allegro

mat

Computer aided design

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. D’Modelldatei hëlleft Iech déi schematesch ze zéien. 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. (Notiz: d’Detailer vum Designprozess hänkt vum gewielte Software -Tool of).

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

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. Zousätzlech kann den Hiersteller den Apparat duerch d’Testpunkte vun dësem Dokument testen.

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. Am Géigesaz zu enger Schematik, gëtt e PCB Layout déi tatsächlech Komponenten op exakt Plazen op der PCB zou a weist d’Gleiser déi all Komponent matenee verbannen tëscht de PCB Schichten. 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 dës Manéier kënnt Dir d’leitend Spuer kuerz halen a Kaméidi an Amëschung reduzéieren.

D’Benotzer Interface (UI) muss och am Kapp gedriwwe ginn wann Dir e PCB designt. Komponente wéi Audio Jacks, Connectoren, LEDs, asw musse ugepasst ginn fir déi bescht Benotzererfarung z’erreechen.

Once the layout is designed, a Gerber file is generated. Äre PCBA Hiersteller benotzt dës Datei. There are many companies that offer these services, and from HWTrek’s expert library we recommend Kingbrother, NexPCB, and HQPCB.

Sample Gerber files

D’Placement vun de Komponenten op der PCB ass ganz wichteg. 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. Dëst wäert d’Basis sinn fir d’Fondatioun weider ze bauen fir Komponente fir de PCB ze addéieren an d’PCBA ze fabrizéieren (gedréckte Circuit Board Assemblée).

Unassembled PCBS

PCBA (Assembly)

Material Virbereedung

Zu dësem Zäitpunkt an Ärem EE Design sollt Dir d’Komponente gewielt hunn. You can ask the PCBA manufacturer to order the required components for you, or do it yourself if you choose a supplier. Mataarbechter déi Opmierksamkeet brauchen:

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 order quantity: Check the minimum order quantity of the component. Wann Dir manner wéi de Minimum kaaft, gitt sécher datt déi gewielte Komponenten op Lager sinn. For small batches (up to 50), you can order online from DigiKey or Mouser. Fir méi Quantitéiten, frot w.e.g. Berodung vun Ärem Hiersteller.

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 (Surface Mount Technology) ass déi am meeschte verbreet Method bei der Masseproduktioun. It is done by fast, accurate SMT machines that save you time, money and avoid human error.

Saachen ze erënneren:

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.

Löt zréckfléissen

Reflow soldering is the process of making components “stick” to the PCB. De PCBA erhëtzt de Circuit Board duerch e Refloofofen oder eng Infraroutlampe bis de Solde schmëlzt, an doduerch d’Komponent permanent un de Circuit Board befestegt.

The trickiest part here is not to overheat or damage the components, because the thermal characteristics of each package are different. En zouverléissege PCBA Hiersteller ass verantwortlech fir dëse Prozess, an alles wat Dir maache musst ass hinnen Komponent Spezifikatiounen ze liwweren.

Reflux Prozess.

Other welding methods:

Wave-Lötung gëtt haaptsächlech fir manuell bäigefüügt Komponente vun der Duerch-Loch Method benotzt. An dësem Fall wäert Äre PCBA fir d’éischt duerch de Reflow Schmelzofen goen, an dann manuell aner Komponenten derbäigesat nodeems se duerch d’Welle Solderen Maschinn geet.

Eisen Schweess kann fir spezifesch Situatiounen benotzt ginn, awer net fir Masseproduktioun.

Testen a Qualitéitskontroll

An dësem Schrëtt gi PCBA Proben getest fir d’Qualitéit ze garantéieren. Gemeinsam Feeler sinn: Kuerzschléi an ofgetrennten Komponenten, falsch ausgeriicht Komponenten an Deeler vum Circuit déi net ugeschloss solle ginn. Déi meescht üblech Tester:

ICT (Online Testen). When designing a PCB, some test points are usually reserved for debugging, programming, and other purposes. D’ICT Maschinn benotzt dës Testpunkte fir oppen/Kuerzschluss Tester a kontrolléiert ob d’Wäerter vun de passive Komponenten (Widderstänn, Induktoren, Kondensatoren) am Spezifizéierungsberäich sinn.

AOI (Automatesch optesch Inspektioun). Manufacturers use a “gold sample” (reference PCBA) to compare with other samples. Fir dësen Test muss den Hardware Creator den Hiersteller Spezifikatioune an Toleranzen ubidden fir d’Parameteren ze setzen.

Röntgen. The PCBA manufacturer will use X-rays to check the welding conditions of the BGA (ball Grid Array) components. Kuckt de Röntgen Test an dësem Video.