What causes PCB failure?

Three reasons cover most failures:

PCB design problem

Environmental reasons

age

PCB design issues include various problems that can occur during the design and manufacturing process, such as:

Component placement – Incorrectly locates components

Too little space on board causing overheating

Parts quality issues, such as the use of sheet metal and counterfeit parts

Excessive heat, dust, moisture and electrostatic discharge during assembly are just some of the environmental factors that can lead to failure.

Stopping age-related failures is more difficult and comes down to preventive maintenance rather than repair. But if a part does fail, it is more cost-effective to replace the old part with a new one rather than throwing out the whole circuit board.

What should I do when PCB fails

PCB failure. It will happen. The best strategy is to avoid duplication at all costs.

Performing PCB fault analysis can identify the exact problem with the PCB and help prevent the same problem from plaguing other current boards or future boards. These tests can be broken down into smaller tests, including:

Microscopic section analysis

PCB weldability test

PCB contamination test

Optical/microscope SEM

X ray examination

Microscopic slice analysis

This method involves removing a circuit board to expose and isolate components and helps detect problems involving:

Defective parts

Shorts or shorts

Reflow welding leads to processing failure

Thermal mechanical failure

Raw material issues

Weldability test

This test is used to find problems caused by oxidation and misuse of solder film. The test replicates solder/material contact to assess solder joint reliability. It is useful for:

Evaluate solders and fluxes

Benchmarking

Quality control

PCB contamination test

This test detects contaminants that can cause degradation, corrosion, metallization and other problems in lead bonding interconnects.

Optical microscope/SEM

This method uses powerful microscopes to detect welding and assembly problems.

The process is both accurate and fast. When more powerful microscopes are needed, scanning electron microscopy can be used. It offers up to 120,000X magnification.

X-ray examination

The technology provides a non-invasive means of using film, real-time or 3D X-ray systems. It can find current or potential defects involving internal particles, seal cover voids, substrate integrity, etc.

How to avoid PCB failure

It’s great to do PCB fault analysis and fix PCB problems so they don’t happen again. It would be better to avoid breakdowns in the first place. There are several ways to avoid failure, including:

Conformal coating

Conformal coating is one of the main ways to protect a PCB from dust, dirt and moisture. These coatings range from acrylic to epoxy resins and can be coated in a number of ways:

brush

spray

impregnated

Selective coating

Pre-release testing

Before it is assembled or even left the manufacturer, it should be tested to ensure it does not fail once it is part of a larger device. Testing during assembly can take many forms:

In – line test (ICT) energizes the circuit board to activate each circuit. Use only when few product revisions are expected.

The flying pin test cannot power the board, but it is cheaper than ICT. For larger orders, it may be less cost-effective than ICT.

An automated optical inspection can take a picture of the PCB and compare the picture with the detailed schematic diagram, marking the circuit board that does not match the schematic diagram.

The aging test detects early failures and establishes load capacity.

The X-ray examination used for pre-release testing is the same as the X-ray examination used for failure analysis tests.

Functional tests verify that the board will start. Other functional tests include time domain reflectometry, peel test and solder float test, as well as solderability test previously described, PCB contamination test and microsection analysis.

After-sales Service (AMS)

After the product leaves the manufacturer, it is not always the end of the manufacturer’s service. Many quality electronic contract manufacturers offer after-sales service to monitor and repair their products, even those they did not initially produce. AMS helps in several important areas, including:

Clean, test and inspect to prevent equipment-related accidents and failures

Component-level troubleshooting to service electronics to the component-level

Recalibration, refurbishment and maintenance to refurbish old machinery, remanufacture special parts, provide field services and update and revise product software

Data analysis to study service history or failure analysis reports to determine next steps

Outdated management

Obsolescence management is part of AMS and is concerned with preventing component incompatibilities and age-related failures.

To ensure that your products have the longest life cycle, outdated management experts will ensure that high quality parts are supplied and conflict mineral laws are complied with.

Also, consider replacing the circuit card in the PCB every X years or returning X times. Your AMS service will be able to set a replacement schedule to ensure the smooth operation of electronics. It’s better to replace parts than wait for them to break!

How do you determine the right test

If your PCB fails, you now know what to do next and how to prevent it. However, if you want to minimize the risk of PCB failure, work with a quality electronics manufacturer with experience in testing and AMS.