USB Printed Circuit Board(PCB) Guidelines

What is USB PCB?

A USB(Universal Serial Bus) circuit board is the central core of any USB serial interface device. These boards are widely used because of their quick data transmission, more straightforward interface, and hot-swapping support. In addition, the efficiency of this PCB helps corporations and businesses to exchange documents easily. As a result, the use of this USB PCB is increasing. Some of the everyday purposes of using this PCB include:

• Exchanging documents
• Lock and unlock the computer systems
• Operate the program to connect wirelessly
• Backing up the folder

Benefits of Using USB PCB

USB PCB is getting popular because of its various advantages. Some of the benefits include:

Energy Efficiency

The USB PCB only uses the power for signaling and data transfer purposes. Thus it uses the power from other devices and helps in proper storage and data transformation. 

Ease of Use

The USB board is one of the easiest things to use. You can plug it into another electronic device and transfer the data accordingly.

Speed

It stores data and transfers data at a very high speed. It result is a high-speed operation in data transformation. 

Problem Affecting 

While using the USB PCB, you may plug it in and out over a long period of time. The frequent plug-in and out of the USB PCB could affect the stability of micro-connectors. This may detach the micro connector from the USB board. Thus, below are some of the measures to consider for solving this issue:

Helping Plug

You can place a plug on the printed circuit board lying flat so that it could help.

Using Neutral Cure

If you want to strengthen the support for the micro-connectors, you can use neutral cure silicon rubber or molten glue. 

Types of USB PCB

Some of the standard USB PCBs include:

USB-A

This is the standard connector. It is found on one end of almost every USB cable. It'sUnfortunately, it's a rectangular connector that only fits in one way.

You'll find several USB-A ports on laptops and desktops. In addition, many TVs, game systems, cars, media players, and other devices have one or more. Unfortunately, a cable with USB-A on both sides is hard to find. 

Female USB-A connectors are the standard "host" connectors. Any device intended to connect to peripherals, such as computers or hubs, has this connector. In addition, extensions are available with both female and male A connectors.

USB-A male connector is the standard "peripheral" connector. In addition, many devices include the built-in cables terminating in USB-A male connectors on the other side of their USB cables, like the mouse, keyboards, etc. 

USB-B

It is one of the oldest connectors that is not popular nowadays. At one end, it's almost square and is usually used for printers and similar devices. 

USB-B female

When the size isn't the issue, USB-B females are the preferred way of providing removable USB connectors for peripheral devices. Through-hole board mounts are typically the most reliable, but panel mounts are also available. 

USB-B male

It is almost impossible to find a USB-B male connector anywhere other than on the end of the USB-B cable. Since USB-B cables are inexpensive and ubiquitous, USB-B is also very popular. 

Mini-USB

Mobile devices are best suited for this smaller type of connection. Many cameras, MP3 players, and other devices still use it, although it's been largely replaced by micro-USB. Another cable-only connector is the USB-Mini male. Almost anywhere sells cheap cables for USB-A, as with USB-B. 

Micro-USB

This connector has applications in portable devices and is a recent addition to USB connectors. They use the micro-USB port from the battery pack to the android cellular devices and headsets. At the same time, some cellular devices are practicing the newer USB-C port.  

USB-Micro female is found on many newer devices like MP3 players, digital cameras, etc. In the future, USB-Micro is likely to supplant USB-Mini as the small-factor USB connector of choice as cellular phones and tablets adopt USB-micro as the standard charging port.

The USB-Micro male is known as a cable-only connector. A USB-Micro cable usually has two types of ends: one for attaching a USB-Micro peripheral to a USB host device and one for connecting a USB-Micro female port to a USB-A female port for USB-OTG devices.

USB-C

USB-C is one of the newest USB standards. The USB-C cable provides a direct connection between devices that both have USB-C ports, instead of older cables that usually had a USB-A port on one end and a different type on the other. Also, it is reversible. USB connector in USB C packs 24 pins. USB C cables can also carry currents above 500mA for devices that consume great power.

Some of the brands are using this standard, including some of the newer android phones like google pixel devices, Samsung Galaxy S9, etc. In addition, some of the apple modes are also using it. But not every thunderbolt 3 supports the USB-C port. Thus, it isn't very clear with this standard. 

Below is the list of all types of USB PCB:

• USB Type A PCB
• USB Type B PCB
• USB Type C PCB
• USB 3.0 Type A PCB
• USB 3.0 Type B PCB
• USB 3.0 Micro B PCB
• USB Mini B PCB
• USB Micro B PCB

USB Circuit Board Design Components

Some of the common components for designing the USB PCB include:

Shielding

The major work of shielding is to protect and preserve the electrical signal that runs through the USB circuit board. This happens especially when the PCB is placed in a high electrical noise environment. Providing extra security and coverage requires the metal covering, but it is not part of the PCB. 

Strong Power Connections

The major work of this power connection design in USB connectors is to make the power pins. It helps in providing power connectivity before the data connectivity. Not only this, but it also helps power the device above the data lines.

Polarization

There is only one orientation in any of the USB connectors. Thus it should be connected in only one direction. If you try to connect the connector in a reverse way, then it will damage the device.

Strain Relief

To minimize tension on connectors, plastic coatings provide strain relief. The coating also prevents cord stress from damaging the USB device. 

Four Contacts

Most all USB connectors have at least four contacts. While USB 3.0 could have more connections than five. These higher contacts can be spotted on the outer plastic bar. Among the four basic contacts, two are the data lines with D+ and D- signs, and the remaining two are the power and the ground lines. 5V and 500mA are the Voltage and the current that flows through these connectors.  

USB PCB Thickness

If you want your USB PCB board to operate smoothly, make sure it has the right thickness. Most PCBs will work with a 1.6mm thickness. It may, however, be better for some applications to use a 2mm thickness. Adding some thickness to the USB connector through the application of green electrical tape was required since it needed to be thicker than 1.6mm. There is currently a wide range of plug thicknesses on the market. For example, apple's Lightning connector is only 1.5mm thick, while Micro USB plugs are 1.8mm thick. The thickness of USB C plugs is 2.40mm.  

Things to Consider before Designing a USB PCB

There may be a problem finding replacement connectors for older devices with USB C.

Designing the thinner USB circuit board is challenging. It must contain various crucial factors for selecting the thickness of a USB circuit board. Some of them include:

Space

The potential packaging space of the PCB plays a role in determining the PCB thickness. Thinner boards take up less space for packaging, while thicker boards occupy more. Therefore, small devices should use tiny printed circuit boards, while large devices can use thicker ones. For example, compared to PCBs for industrial equipment, USB connectors for Bluetooth headsets need to be thinner.

Connections

The connection of the PCB determines the thickness of the PCB design. Due to the differences in connectors, it is necessary to ensure that PCB traces can match the connector's mating segment thickness. 

Impedance Matching

More than two layers act as the capacitor while tracing the contiguous layers. The thickness of the PCB determines the dielectric values. For the high-frequency signal with matching impedance, you need to consider the capacitance before getting the correct thickness on your design.

What is USB PCB Board Price?

USB PCB is available in various sizes with various functionalities. This variation of USB PCB in terms of working, quality and size results in a variation in the cost of USB PCB. Thus the types of PCB determine the cost of a USB board. The high-quality UCB board is costlier and contains a greater storage capacity. Thus the cost also differs based on the storage capacity of the USB PCB. Anyway, the cost of a USB PCB lies between $3-15 for various kinds of USB PCBs.

The Thing to Check before Buying a USB PCB

Before buying or fabricating the USB PCB, you need to make sure to check the following feature of the USB board:

Mechanical Feature

The mechanical system increases usability. It includes elasticity, elongation, hardness, fatigue limit, etc.

Electrical Features

You should check the conducting ability of the USB PCB for transmitting the signal through the wires. The main electrical feature that you should consider include electrical conductivity, dielectric strength, resistivity, and thermoelectricity.

Thermal features

The thermal features like the coefficient of thermal expansion, thermal conductivity, heat capacity, and thermal stress are the thermal features that require constant checking. 

Chemical Features

The chemical property indicates the response of USB PCB during exposure to various chemical elements. It includes the features like acidity, toxicity, resistance to erosion, flammability, etc.

Types of USB PCB Connectors

USB PCB connectors have the following types:

Vertical Through Hole Connectors

These connectors have an upright orientation. It is the female USB type. It contains the staged plastic connectors in 3, 2, and 4 rows, with a contact spacing of 0.05. Before connecting the connectors to the board, the terminations pass through coated/plated holes. Slim tracks like this are ideal for applications with limited space. 

Top Mount Connectors

In the PCB's top tier layer, the top mount connectors knot using the break off the lead. It helps handle falling objects and vibration; thus, it is more suitable for mechanical devices. 

Mid Mount Connectors

The mid-mount connectors lie at the midsection until the PCB. The surface mount methods help to mount this connector. These types of connectors are especially suitable for low-profile electronics. 

Base Mounted Connectors

The surface mount technology primarily helps to attach this connector to the PCB's underside. In addition, these connectors help join the two circuit boars with the help of the links between the application passing across the board.

Micro USB PCB Connectors

The micro USB PCB connectors are the most minor USB intersection that helps connect mobile devices. The major benefit of this micro USB PCB connector is the tiny port size compared to other UCB connectors. 

The design of this connector boosts the USB performance. In addition, this technology helps communicate to mobile devices without using the host computer.

It is one of the tiny USB cable types with two connection methods with the addition of USB 3.0. Although the size of this connector is the smallest, it performs all the matches of the USB cables.  

USB C-PCB

The USB connectors undergo various upgrades. This update and optimization come with the change in the shape of the PCB. The impressive innovation and technology help the UCB-C to gain the most acceptance in the electronic world. Some of the reasons that led to this acceptance include:

• Thin and tiny profile
• Quick data transmission speeds
• The proper delivery of the power data simultaneously
• High Voltage and current carrying capacity
• More durable than the USB-B type connector 

Suggestions for USB PCB layout design

• Before designing the USB PCB, some points require the proper checking:
• While positioning the components, make the short differential signal line as possible. 
• On a differential line pair, do not exceed two via pairs.
• For coupling the two wires tightly, apply the symmetrical parallel routing.
• Ensure that the signal and ground networks are at least 20 mils apart from the differential lines to minimize crosstalk.
• Consider the placement of the pull-up resistor, test point, and differential series connection resistance.
• It would be best if you implemented the differential pair mismatch compensation for matching the line length. This is because the differential line length is hard to check due to various trace spaces, pin distribution, etc. 
• The required output current in USBs is 500mV; thus, proper monitoring is required for GND and VBUS line widths. 

Common Problems of USB PCB

Faulty USB PCB Port

The defective USB port can cause an error or malfunction of the USB PCB. Thus first, you must ensure the problem is with the device or the port. Next, check the port's working by plugging the device into another USB port. In that case, if the device works, this indicates an error in the USB port. 

Software Configuration Problem

Incorrect software systems can also cause a problem with USB PCBs. For example, this problem could result after installing a new os or changing the computer settings. Thus, you can check the following steps below:

• Properly check for the settings in the main setup, device manager, and control panel.
• Make sure to check the updated drivers.
• Check for the health of the computer by running the virus scan. 

Hardware Issue

Sometimes there is a problem with the USB PCB that fails the hardware. For example, the expansion slot can fail the USB card, or the wires that connect the USB port to the motherboard could be detached. This result in a problem with the USB port or the controller. Thus one needs to check:

• The connectors and port for first and dust
• The loose components and wire by running the physical check
• Expansion slots, ports, and cables and replace the faulty one
• Wrong Extension Cable

USB PCB can malfunction by the wrong USB extension cables. The malfunctions result from the mismatching of low-speed cables with high-speed accessories. Thus check for the following points:

• Select the right USB extension cables as per your port requirement
• Check for USB types 
• Read the user manual for suitable cable types 

Why Choose a USB-C Connector?

Various reasons say a USB-C PCB connector is best. Some of the reason includes:

• It boosts the efficiency of quality charging.
• It achieves a higher carriage capacity of Voltage and current.
• It contains a durable advantage over the micro USB -B type because of its design mode.

What Stops the Working of the PCB Layout?

The errorless and accurate design of the USB PCB will function smoothly. However, various errors and mistakes can complicate the working of PCB. Some of the points that could result in the malfunction of PCB include:

Incorrect Landing Pattern

In drawing a landing pattern, mistakes and errors are common. Using the components in your designing software library may prevent problems with pin-to-pin spacing.

Wrong Placement of Decoupling Capacitors

Improper and wrong placement of decoupling capacitor causes the issue. Place the capacitor in the power supply rails. This capacitor should be near the input voltage pins.

Insufficient Power Trace Width

The signal power is transmitted successfully through the trace if it has the proper width. However, in case of wrong trace widths, the whole working of the board can malfunction. Therefore, use the minimum width requirement and use the trace width calculator for correct measurement.

Application of USB PCB

• USB PCBs have a wide range of application some of them includes:
• Vehicle systems in the automotive industry for storing the key information
• Communication Industries like mobile phones, communication equipment, and computers.
• Medical Industry transfers the information and documents
• Entertainment industry for storing movies and music etc.

Process USB PCB Routing

While laying the new design of the USB PCB, make sure to use the following routing and placement guidelines:

• Initially, make sure to put the major components and high-speed USB controller in the unrouted board.
• Routing high-speed clocks and high-speed USB differential pairs with minimum trace lengths are essential. Make sure that connectors leaving the PCB are as far away from high-speed clocks/periodic signals as possible. 
• Using a minimum number of corners and vias, route the high-speed USB signals. This helps in reducing the reflection of signal and also impedance changes. 
• Ensure USB traces aren't routed underneath crystals, magnetic devices, oscillators, ICs, and clock synthesizers. 
• Avoid the stubs in high-speed USB signals. This could affect the signal quality and signal reflections.
• Make sure to route all the traces in the GND plane without interruption.

Conclusion

USB-PCB is growing in today's market. Although there are some common problems while manufacturing and designing the PCB, the errors can be avoided using a practical and careful approach. First, make sure you have a quality check before finalizing the design. Ensure you are following the design suggestion. You can contact us, NextPCB if you have any design-related problems.

NextPCB provides quality PCB services, including all USB PCBs, HDI PCBs,5G PCBs, flexible PCBs, etc.