How to Prevent Common PCB Failure Modes: A Practical Guide

Jan 11,2021

A printed circuit board (PCB) is one essential and integral element of most electronic applications. They bring life to many electromechanical and electronic devices such as televisions, street lightings, cellphones, and many more. Thus, it can be extremely disruptive when they fail. There are several reasons for PCB failure. Anything ranging from the harsh weather to age can cause havoc on the circuit board, causing complete failure of the device. Therefore, it is important to understand the causes of PCB failures to prevent future occurrences. This post discusses the most common PCB failure causes and the dos and don’ts to avoid them.

What Are the Reasons for PCB Failure?

A well-designed and successfully manufactured circuit board that fulfills its performance objectives over its lifespan is always the expectation of any original equipment manufacturer (OEM). However, some crucial aspects may be overlooked by the PCB manufacturer at times. Undoubtedly, the circuit board design process can be tedious and time-consuming depending upon the complexity of the board, and each of which carries some degree of risk. The main reasons for the circuit board failure include an under-specified design, manufacturing defects, environmental factors, and so on. While a few factors can be mitigated in the circuit board design phase, proper planning during the design phase can help the board perform its best. The next section describes what failure modes can occur and be detected during circuit board assembly and operation.

A Brief Discussion on Most Common PCB Failure Causes

• Manufacturing Defects:

  This is one common reason for PCB failure. These defects are hard to detect and even more difficult to fix. Some of the manufacturing defects can be headed off in the design, while others should be fixed by the OEMs. Here are some common manufacturing defects:

• Layer Misalignment:

  The PCB stack-up alignment is done during fabrication and it is difficult to detect any alignment issue until the circuit board is being completely assembled. For instance, at the time of manual inspection, if opens, shorts, or crossed lines occur, then it will negatively affect the circuit board operation.

• Solder Bridging:

  This is another common defect that occurs when the solder forms an abnormal connection between two or more adjacent traces, pads, pads, and traces in close proximity.

• Component Shifting:

  The components are placed before soldering during assembly. If the component shifts even slightly during soldering, then a quality solder joint will not form. This may result in tombstoning.

• Board Breakage:

  The circuit board may fail due to mechanical or physical stress such as. vibrations or repeated shocks. Sometimes, the board can break if its bending capability ratings are exceeded.

• Component Functionality Deterioration:

  The failure of the component is another major problem. Components may fail due to poor or low quality, wrong selection, package breakage due to excessive heat, chemical interaction, and many more.

• Performance Degradation:

  This is one of the hardest failure modes to detect. The gradual degradation of performance may occur due to many reasons including trace degradation, oxidation, condensation, incorrect copper weight, and many more.

• Delamination:

  As the name implies, delamination occurs when the board lamination detaches from the dielectric material. The main cause is the use of material where the coefficient of thermal expansion (CTE) is low for the thermal requirement of the environment.

Above-mentioned failure modes that a board must survive to meet its lifecycle operation objective. Fortunately, these failures can be avoided with decisions that can be made while designing boards to improve the probability.

PCB Design Dos and Don’ts to Avoid Failure Modes

With the following dos and don’ts, it is possible to avoid PCB failure mode contingencies.

Design Dos to Avoid PCB Failure Modes

• One of the best ways to avoid PCB failures is to choose the best materials and quality components. The selection of material as well as a component should be optimized for the circuit board design while ensuring availability and quality.

• Another important consideration is who should build the circuit board? Selecting a quality fabrication and assembly services provider can make a significant difference in PCB development.

Design Don’ts to Avoid PCB Failure Modes

• Don’t assume thermal resistance for the circuit board. Instead, analyze it. It is one of the best ways to test whether the board can sustain the heating requirement of the assembly.

• Don’t assume reliability. Hence, the prudent and best approach is to conduct circuit board testing and ensure the board’s design and functioning.

With the above design guidelines, you will significantly reduce the probability of PCB failure modes during assembly. Are you interested to know more about PCB design guidelines? If yes, then you can contact industry-leading PCB manufacturers like Creative Hi-Tech. Their highly experienced experts will assist you throughout the process. 

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