How to make your own PCB business card

Homemade PCB Business Cards

Overview: Business cards are often used when conducting business-related activities but in this era, traditional paper business cards simply are not enough in terms of attracting the attention of other parties or partners. This article, by FS Technology, will teach you how to make a modern, practical PCB business card which will make you stand out from other competitors.

Foreword

What you will learn from this project:

  • The process of making a simple PCB business card
  • The manufacturing process of high-end PCB business cards with NFC (Near Field Communication) functionality

Required tools and skills

Essential tools:

  • Soldering Iron
  • Hot Air Rework Tool
  • Solder paste
  • Soldering flux
  • Solder wire
  • Tweezers
  • Cross-lock tweezers
  • PCB cleaner
  • Cotton swabs
  • Toothpicks
 

Optional tools:

  • Smoke exhauster
  • Ornate glass
  • Phone with NFC
  • NFC Chip 1kb
 

Required skills:

  • SMD soldering skills
 

Bill of Materials:

  • Printed Circuit Board
  • 220 nF capacitor
  • 47Ω resistor
  • LED

Simple Printed Circuit Board Business Card Manufacturing Process

Making the PCB schematics

Although other PCB design tools may be used, EasyEDA is recommended by us to draw the PCB schematics as it has a built-in simulator for signal measurements. You can also find the required circuit schematics of the components in the EasyEDA library.

  • Import the desired pattern into layer 22 “bPlace” and it will appear on the silkscreen of the PCB, above the black solder mask.
  • Introduce light on layer 16 “Bottom”, which will be seen as copper traces covered by the black solder mask.
 
The schematic diagram of a simple PCB business card is relatively simple as, except for the USB connector, all the components used on the circuit board are SMD (Surface Mount Discrete) parts. Even so, you will still need to know how the circuit boards work because you will need to sketch their design on the file.

PCB Business Card Template Design

Because your personal information (name, phone, etc.) needs to be recorded at the top of the panel, you will need to customize part of the ground plane and enter the information you need to display on layer 29 “tStop”. This layer is the solder mask that controls the top. Text overlays on the top and “tStop” layers can make your PCB business cards look better.

Precautions for Inductive Antennas

Radio waves cannot pass through the PCB board, so when designing the antenna, there must be no copper sheets above and below it. The correct way is as follows:

Correct Antenna Settings

When there is copper above the antenna, the ground plane of the PCB will block the reader, and energy cannot be transmitted between the NFC tag antennas, as shown in the following figure:

wrong antenna settings

Precautions for assembly of business card components

Before proceeding with PCB assembly, you need to know the rules of PCB component orientation. To make your PCB business card more beautiful, you can place the components on the bottom of the PCB board and place the LED on the bulb filament. If you’re making an NFC-enabled business card, you’ll need to connect wires to the NFC IC.

Generating Gerber files

Gerber files are used by the PCB industry to “describe” PCB images and are required whether you are making your own DIY PCBA board or outsourcing the fabrication to a professional turnkey PCBA assembly company, such as FS Technology. After completing the schematic diagram, you can click the “convert” button in EasyEDA to convert the schematic diagram into a PCB design or if you are using Eagle, you can export Gerber files by using the built-in CAM processor.

Ordering your PCB board

If you want a high-quality PCB business card, you can send your order to FS Technology as we have the most advanced equipment, a highly-trained technical team and the cheapest price. As professional PCB manufacturing experts in China, we recommend the following designs for your custom board:

Ordered printed circuit board

Component installation

The purpose of a PCBA board is to connect the different components through the “lines” or traces on the bare board to achieve different functions, primarily electrical conductivity between components, so PCB assembly is an essential part of completing the circuit. For this, you will need to solder the SMD components to the PCB board, then use the programmer to write the code into the microcontroller and finally do a PCB assembly inspection.

Packaging PCB business cards

You can use foam double-sided tape to seal the edge of your assembled PCBA board by printing a mask to then put on the foam double-sided tape. Subsequently, you can cut off any excess tape to complete your creative PCB business card.

PCB Business Card with NFC

Introduction to NFC Technology

What is NFC?

NFC, also known as Near Field Communication, is a contactless identification and interconnection technology (similar to Bluetooth PCB) which enables your mobile devices and consumer electronics to communicate within a range of < 10 cm. In recent years, devices used in popular mobile payment, identity authentication, transportation card recharge, etc all have been relying on NFC.

How does NFC work?

The NFC working mode is divided into two modes, passive and active mode, but this article will only describe the active mode. When the signal-sending device sends data to the target device, it must generate a radio frequency field, which can then use the electromagnetic induction between the two loop antennas to charge the passive target (tag), as shown in the figure:

NFC schematic

NFC Chip Fabrication

Chip Requirements:

  • Small SMD package
  • Adequate storage capacity
  • Embedded energy harvesting module
 

If you use a printed circuit board as a business card, the NFC chip is at its heart and although the choice of the core can be varied, this article will recommend NXP’s NTAG NT3H1101 IC. Many electronics enthusiasts have programming abilities, they can do IC programming by themselves to get more functions.

NTAG i2c is the latest passive TAG chip with an I2C interface released by NXP, which is an agent of the Dalian Dapinjia group. It is widely used in household appliances, consumer electronics, wearable technology, home automation and other fields as it provides both contactless and contact interfaces as shown:

NTAG I2C

Calculate Antenna Inductance

In order for the PCB business card to communicate and power up, we need to add an antenna to the NFC tag. The antenna design of the NFC chip is relatively simple, as shown below:

Explanation of the icons in the picture above:

  • Voc: Magnetic field-induced open circuit voltage
  • Ra: Equivalent resistance
  • La: Equivalent inductance
  • Rs: series equivalent resistance
  • Cs: Serial Equivalent Tuning Capacitance
 

When the transmitter senses a magnetic field, an open circuit voltage Voc appears at its terminals.

The sum of the series resistances Ra and Rs is the equivalent model of the circuit consisting of the NFC integrated circuit and its loop antenna, as shown in the following figure:

The NFC IC resistance Rs forms a resonance circuit RLC together with the antenna resistance Ra and the built-in capacitance Cs with the inductance La of the antenna.

The frequency formula of the resonant circuit RLC is shown in the figure:

The formula for calculating the RLC of the resonant circuit

Resonant frequency formula parameters explanation:

  • F: resonance frequency, unit: Hz
  • L: Equivalent inductance, unit: H
  • C: Equivalent capacitance, unit: F
L is an unknown parameter in this equation and L needs to be calculated separately. The formula diagram is as follows:

Example: Assuming the frequency of NFC is 13.56 MHz an d the tuning capacitance is 50 pF, bring it into the formula to get the inductance L as:

Example diagram of inductance L

Rectangular Antenna Calculation

Only by obeying the geometric constraints, we can add a specific inductance antenna to the PCB board. Antennas with different geometries require different formulas to support them. In order to facilitate the explanation, FS Technology uses a relatively simple rectangular antenna to design PCB business cards, as shown in the following figure:

Rectangular Antenna for PCB Business Cards

Explanation of the units in the diagram above:

  • A0 & B0: Overall size of the antenna
  • Aavg & Bavg: Average size of the antenna
  • T: Track thickness
  • W: Track width
  • G: Gap between tracks
  • Nant: Number of turns
  • D: Equivalent diameter of the track
 
The formula for the equivalent inductance Lant is as follows:  
Equivalent inductance Lant

The interpretation of Lant’s formula is as follows:

Lant formula

Create Eagle Library

If you think designing the antenna is cumbersome, you can copy the rectangular open source antenna provided by NXP to design the antenna, and then change the position of the connector.

Design the Antenna

Solder the NFC chip onto the PCB visiting card

Soldering the PCB components is a relatively important step to any complete PCB product but whether it is before or after soldering, PCB cleaning is an essential preliminary step. After cleaning is completed, PCB flux needs to be prepared in advance. Flux can act as a temporary glue by applying it to the IC package with a toothpick, and when the flux is added, you can use tweezers to hold the circuit board components in place. Then, use a new toothpick to take a small amount of solder paste and place it on the pins of the components. Both flux and solder paste is commonly used when it comes to soldering SMD components as these techniques are much more accurate compared to standard through-hole soldering. Remember to always control the amount of solder paste used as overusing solder paste is a common problem with many hobbyists new to soldering and it can cause circuit board short. The final step of the soldering process is to use a hot air rework tool to melt the solder paste and solder the IC’s pins to the circuit tracks. With the use of a hot air rework tool, it eliminates the need for a traditional soldering iron which can be a bit more tricky to solder such miniature components with, especially by hand. After this process, it is always recommended to visually check the connectivity of each component to ensure that there are no solder bridges or misalignments of components. A microscope may be useful for smaller components. To enhance the look of your PCB visiting card, you can use a pre-prepared soldering iron to remove the excess flux in addition to Q-tips and isopropyl alcohol for cleaning. Resistors and LEDs operate in almost the same way and can be soldered with the above steps. Overall, soldering the NFC IC by hand is by far the hardest step in this project and even the slightest mistake can lead to a short circuit. If mistakes are made during this process, it is recommended that you know some skills of desoldering PCB components as it can help reduce losses in the case of any mistakes. Similar to many other skills, constant practice of SMD soldering is the best way to improve your soldering techniques and could be a very helpful skill when working on other projects involving SMD components.

NFC chip IC programming

  • NFC Tools for Android: Find the settings menu on your Android device and open the NFC settings.
  • iOS NFC Tool: The NFC tool on your iOS device (iPad, iPhone, etc) will start automatically. Launch the NFC tool, find the “Write” button, click “Add Record”, select “URL” as the record, enter the URL you want the NFC tool to transmit, click the “OK” button and then enter the NFC tag on the “Write” page. When the dynamic icon is displayed, hold the phone close to the business card and the LED on the business card should light up. When the icon shows “Writing completed”, your NFC PCB business card is complete.

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