Los ntawm cov qauv hluav taws xob ntawm cov laug cam los tsim peb tus kheej luam tawm hauv Circuit Court board (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 tsim “lub hlwb” ntawm cov cuab yeej ua haujlwm li cas. 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). Khoom qhov ntev tau teev tseg thaum txheej txheem tsim hluav taws xob. You can watch a video about it here. 2. PCB txheej – Cov txheej ntau dua, cov txheej txheem nyuaj ntawm PCB. (Nco tseg: Txawm tias ib txheej PCB tuaj yeem yog PCB nyuaj, tab sis ntawm no peb tab tom tham txog qhov nyuaj ntawm kev ua PCB. Ntau txheej txheej PCB muaj, kim dua nws yog kev tsim khoom.)

Layer 2 is usually used for simple toy products

Iot cov khoom lag luam feem ntau muaj 4 txheej

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.

Cov ntaub ntawv koj xav tau muab rau PCB cov tuam txhab tsim khoom:

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

Cov ntaub ntawv (FR-2 (ntawv paj rwb phenolic), FR-3 (paj rwb ntawv thiab epoxy), FR-4 (iav fiber ntau thiab epoxy … Etc.)

Thickness (0.5 hli, 1.0 hli … Etc.)

Color (red, black, green… Etc.)

Kev kho qhov chaw (ENIG (tshuaj lom npib tsib xee/kub kub), DIG (tso dej kub ncaj qha), OSP (cov tshuaj tiv thaiv kab mob pov tseg, thiab lwm yam)

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

Cov ntaub ntawv Gerber

PCB design process:

Tus qauv tsim hluav taws xob

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

Zaus ntaus ntawv

KiCad

Cadence lub suab paj nruag

lev

Khoos phib tawj pab tsim

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. Cov qauv ntaub ntawv yuav pab koj kos duab schematic. 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. (Note: the details of the design process will depend on the software tool chosen).

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. Koj yuav tsum tau xaiv cov khoom (lossis tam sim no xaiv lawv), thiab peb piav qhia cov txheej txheem no hauv EE Tsim Txheej Txheem video (saib 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. Ib qho ntxiv, cov chaw tsim khoom tuaj yeem ntsuas lub cuab yeej los ntawm cov ntsiab lus ntsuas ntawm daim ntawv no.

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. Tsis zoo li cov txheej txheem, PCB txheej txheem muab cov khoom sib piv rau qhov chaw nyob ntawm PCB thiab qhia cov kab uas txuas txhua qhov kev sib koom ua ke ntawm PCB txheej. 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. Hauv txoj kev no, koj tuaj yeem khaws cov ntawv coj ua luv thiab txo cov suab nrov thiab cuam tshuam.

Tus neeg siv cuam tshuam (UI) kuj yuav tsum tau nco ntsoov thaum tsim PCB. Cheebtsam xws li lub suab txuas, txuas, coj, thiab lwm yam yuav tsum tau hloov kho kom ua tiav cov neeg siv tau zoo tshaj plaws.

Once the layout is designed, a Gerber file is generated. Koj lub PCBA chaw tsim khoom yuav siv cov ntawv no. There are many companies that offer these services, and from HWTrek’s expert library we recommend Kingbrother, NexPCB, and HQPCB.

Sample Gerber files

Kev tso cov khoom sib txuas ntawm PCB yog qhov tseem ceeb heev. 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. Qhov no yuav yog lub hauv paus txhawm rau tsim lub hauv paus ntxiv rau cov khoom sib txuas rau PCB thiab tsim PCBA (luam tawm pawg thawj coj los sib dhos).

Unassembled PCBS

PCBA (Assembly)

Cov khoom siv npaj

Hauv qhov no hauv koj li kev tsim EE, koj yuav tsum tau xaiv cov khoom siv. You can ask the PCBA manufacturer to order the required components for you, or do it yourself if you choose a supplier. Teeb meem xav tau kev saib xyuas:

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. Yog tias koj yuav tsawg dua qhov tsawg kawg nkaus, xyuas kom tseeb tias cov khoom xaiv tau muaj hauv Tshuag. For small batches (up to 50), you can order online from DigiKey or Mouser. Xav paub ntau ntxiv, thov nrhiav tswv yim los ntawm koj lub chaw tsim khoom.

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 (nto tshuab thev naus laus zis) yog txoj kev siv dav tshaj plaws hauv kev tsim khoom loj. It is done by fast, accurate SMT machines that save you time, money and avoid human error.

Tej yam uas yuav tau nco ntsoov:

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

Reflow soldering is the process of making components “stick” to the PCB. PCBA ua kom sov lub rooj tsav xwm hluav taws xob los ntawm lub tshuab ua kom sov rov qab lossis lub teeb taws ci kom txog thaum lub tshuab yaj yaj, yog li txuas mus tas li txuas rau cov khoom siv hluav taws xob.

The trickiest part here is not to overheat or damage the components, because the thermal characteristics of each package are different. Ib lub chaw tsim khoom PCBA uas ntseeg tau yuav yog lub luag haujlwm rau cov txheej txheem no, thiab txhua yam koj yuav tsum tau ua yog muab lawv nrog cov khoom tshwj xeeb.

Reflux process.

Other welding methods:

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.

Hlau vuam tuaj yeem siv rau qhov xwm txheej tshwj xeeb, tab sis tsis yog rau kev tsim khoom loj.

Kuaj thiab tshuaj xyuas zoo

Hauv qib no, kuaj PCBA raug kuaj xyuas kom zoo. Qhov ua yuam kev feem ntau yog: cov hluav taws xob luv hauv cov khoom sib txuas tsis sib xws, cov khoom siv tsis sib xws thiab ib feem ntawm qhov Circuit Court uas yuav tsum tsis txhob txuas nrog. Cov kev xeem ntau tshaj:

ICT (Kev xeem online). When designing a PCB, some test points are usually reserved for debugging, programming, and other purposes. Lub tshuab ICT yuav siv cov ntsiab lus ntsuas no rau qhib/luv Circuit Court kuaj thiab txheeb xyuas tias qhov muaj txiaj ntsig ntawm cov khoom tsis sib haum (cov neeg tiv thaiv, cov khoom siv hluav taws xob, cov khoom siv hluav taws xob) nyob hauv qhov tshwj xeeb.

AOI (Tsis siv neeg kuaj qhov muag). Manufacturers use a “gold sample” (reference PCBA) to compare with other samples. Txog qhov kev sim no, tus tsim khoom kho vajtse yuav xav tau muab cov lus qhia tshwj xeeb thiab ua siab ntev rau cov chaw tsim khoom los teeb tsa qhov ntsuas.

Xoo hluav taws xob. The PCBA manufacturer will use X-rays to check the welding conditions of the BGA (ball Grid Array) components. Saib X-ray xeem hauv daim vis dis aus no.