Common Causes of PCB Failure

Printed circuit boards are essentially the lifeblood of the devices we use every day. Cell phones, TVs, cars, street lights, and many other devices rely on PCBs, which is why it can be extremely disruptive when one of them fails.

There are many reasons why PCBs fail, sometimes even before they are shipped for use. By understanding the causes of PCB failures, you can more easily prevent future failures and enjoy more efficient PCB testing.

The following are the most common causes of PCB failure:

Defects are the most common cause of PCB failure. Oftentimes, defects occur during the PCB assembly process.

PCBs are extremely sensitive to Electrostatic Discharge (ESD), and while we can only experience thousands of volts of ESD, the smallest discharge can cause component defects. This can be latent (meaning the PCB remains functional but with reduced reliability) or catastrophic (meaning permanent damage has been done.)

Other potential pitfalls include:

Misaligned layers

Short circuit

Cross signal

Reliable PCB manufacturers take several precautions to eliminate electrostatic discharge on the production floor. This includes ESD safe coveralls, shoe grounders, and dissipative floors and work surfaces.

Component burnout is one type of PCB defect, but it is worth noting that it is the main cause of PCB failure. Burned-out components not only require replacement parts, but may also require an overhaul of the entire board. 

The three main causes of component burnout include:

Extreme heat: If the machine overheats or the circuit board is directly exposed to flames, the likelihood of heat-related defects increases. The Tg (glass transition temperature) of the PCB should be 170℃ and the operating temperature should be 25℃ lower than the Tg. 

Improper component spacing: Components that are too close together on the board can heat up, affecting the performance of adjacent components. Designing a PCB with an optimal amount of space is critical to avoiding thermal-related defects. 

Component failure or technician error: If the board is not connected properly or the voltage protection is not up to standard, there is a higher risk of the board burning. Having detailed hookup instructions can help mitigate technician errors. 

Circuit boards are also sensitive to external factors. Heat and humidity can cause the PCB to expand, resulting in warped and potentially damaged solder joints. This is why PCB manufacturing is usually performed in climate-controlled environments where humidity is maintained at safe levels.

Foreign objects in contact with the circuit board can also have a detrimental effect. Many things can get into your assembly and cause overheating, such as:

Dust

Hair

Liquid

Fiber

Solder is a key ingredient in the PCB process. It is what keeps the contact between the component and the circuit, but it can occasionally become contaminated and cause the board to fail. If there is too much moisture in the solder, it can become conductive and cause a short circuit.

But it's not just the consistency of the solder you have to worry about, it's also a mounting error. There are several common types of solder defects, each of which affects circuit boards in different ways.

Open

Too much solder

Component displacement

Cold junction

Solder bridge

Webbing and Splash

Lifting pads

Often, proper training and practice of your assemblers can remedy these welding deficiencies.

Design engineers, assemblers, quality engineers, and seemingly countless others are involved in the production cycle. So it's no surprise that human error plays a role in more than a few PCB failures. Lack of honest (or lazy) mistakes that can damage PCBs, including:

Misreading the schematic

Wrongly installed components

Place traces too close together, resulting in shorts

Poor welding

Most of these errors can be fixed with rework, but this can cost you time and money.

PCBs tend to age like humans more than fine wine. They start to break down as they get older.

Components start to fail after reaching the end of their expected life cycle and the PCB must be repaired or replaced with a new one.

The above briefly understand the reasons for the failure of the PCB board. If you want to buy a PCB board, please contact us.

Singo is a professional custom PCB board manufacturer. Our company mainly deals in PCB assembly and OEM/ODM electronic manufacturing services. The products involve home appliances, digital products, industrial control, and medical equipment. After years of hard work, we have established long-term cooperative relations with some internationally renowned companies. Some of our products are often required to operate in harsh environments where quality and reliability are paramount. With years of experience, we have won a good reputation among customers in the field of electronic production with reasonable prices, abundant resources, and on-time delivery.