Tag: pcb failures

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PCB Blog

What is PCB OUTGASSING?

To ensure that defects are not created during production and use, PCB manufacturers outgassing printed circuit boards during production. Find out what can be done to prevent or reduce outgassing in this article.

What is PCB outgassing?

When outgassing occurs, the gases trapped in the PCB will release within the board in two common situations

During this process, any moisture near the through-hole is turned into vapour by the heat. When this gas escapes, it creates voids in the solder resist layer.

  • Use in ultra-high vacuum environments:

In applications involving ultra-high vacuum environments (such as outer space, laboratories or medical facilities), the vacuum can cause vapour to escape from the PCB, thus creating condensation in the rest of the device.

What are the consequences of PCB outgassing?

Both of these situations occur at different stages of the PCB lifecycle and so present a number of challenges to manufacturers, both of which can lead to defects in the PCB and therefore to a non-functional product.

When outgassing occurs during the soldering process, voids can form in the solder resist layer, which can lead to serious problems. During the deposition process, PCBs need to be drilled and copper plated, with a uniform layer of chemically plated copper acting as a conductor of electricity in the board. Outgassing of PCBs can lead to gaps in the copper plating, which can block the passage of current and cause defects and failures in the PCB.

The problem with outgassing in high vacuum environments depends on the equipment used. In space-related applications, outgassing forms condensate that can interfere with camera lenses or measuring tools, for example, causing problems with measurement results.

Medical facilities and scientific laboratories must have a sterile environment in order to use their equipment properly. Outgassing can contaminate equipment and the surrounding environment, posing a risk to patients or leading to inaccurate test results.

What are the available solutions?

Choosing the right materials

When choosing the materials that make up a PCB, plating made from gold, silver or tin may contain salts or organic substances which can generate gases when heated during the deposition process.

Correct manufacturing

To achieve a high quality PCB then the correct control of the manufacturing process is essential. When the chemical copper plating is too thin or the pre-heating process is incorrect, off-gassing usually occurs during the soldering process.

Even if the PCB has the right material and production method, it can still outgas in high vacuum applications. Baking PCBs for high vacuum systems during production is effective in reducing outgassing, especially when done in vacuum. The baking process removes any residual moisture before use.

Alternatively, when implementing PCBs, customers can design equipment to keep vapours away from critical components. Developing a path for the gas to escape through ventilation holes can prevent it from being trapped.

Choosing the right supplier ensures high quality PCBs

KingPCB is one of the leading PCB manufacturers in China and we have over 15 years of experience in manufacturing, assembly and sourcing of electronic components.

Choose to contact us for any assistance in finding the right PCB for you

 

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PCB Blog

How to Manage PCB Failures？

When a printed circuit board fails, you may face potentially catastrophic and costly consequences. Understanding and preventing PCB failures can minimize the cost of damage.

What causes a PCB failure?

There are three main causes of PCB failure: PCB design issues, environmental and ageing issues.

If there is a problem with the PCB design, it can lead to a variety of problems in subsequent manufacturing processes. For example.

– Inaccurate placement of components

– Overheating due to close spacing of components

Ambient temperature, dust, humidity, etc. during assembly or use can lead to PCB failure.

PCB ageing is inevitable, as everything has its expiry date.

How to fix PCB defeats?

What do you do when your PCB fails? The best way to find out the cause of a failure is to use a printed circuit board failure analysis. The main tests for these are

– Micro-section analysis

– PCB solderability testing

– PCB contamination testing

– Optical/microscopic scanning electron microscopy

– X-ray inspection

Microsection analysis

Microsection analysis of samples is a destructive test, using abrasive paper (or diamond sandpaper) for grinding and subsequent polishing to produce a clear sample profile, and is a rapid method of sample preparation. The use of microsection analysis helps to detect

– Defective components

– Short or open circuits

– Reflow failure

– raw materials

– Thermomechanical failures, etc.

PCB Solderability Testing

PCB solderability testing is used to assess the solderability of components, PCBs, PADs, solder and fluxes by the wetting balance method.

  • Solder and flux quality
  • Quality control
  • Solderability processes

PCB contamination testing

About 15% of PCBA failures are caused by contamination. Ion contamination can cause a variety of problems leading to PCB damage. Testing bare boards for ionic contamination prior to completion of assembly reduces the risk of defects caused by contaminants.

Optical/Microscopic SEM

This method is mainly used to detect PCB soldering and assembly problems.

X-ray inspection

This technique provides a non-invasive method using film, real time or 3D X-ray systems. It can detect current or potential defects, problems involving internal particles, seal cover voids, substrate integrity, etc.

What are the measures to avoid PCB failures?

Use conformal coating

Conformal coatings are one of the main methods of protecting PCBs from dust, dirt and moisture. These coatings range from acrylics to epoxies and are available in a variety of application methods.

  • Manual brush application
  • Spraying
  • Dipping
  • Selective coating

PCB quality testing

PCB manufacturers use a variety of testing methods to check the quality of PCBs during the manufacturing and assembly process.

In-circuit testing

Powering up the board and activating the individual circuits

Flying probe testing

Suitable for sample orders and small quantities

Automatic optical inspection

Photographs of PCBs are taken and compared with detailed schematics to detect boards with markings that do not match the schematic

Aging test

Detects early faults and determines load capacity

X-ray inspection

Function test

Verifies that the board is powered up. Other functional tests include time domain reflectometry, peel test and float test as well as the solderability test, PCB contamination test and micro-section analysis described earlier.

How do I decide on the right test?

Having understood the causes of PCB failures and how to take precautions, you now know what to do next. If you want to minimize PCB failures, choose to work with a PCB manufacturer with extensive experience.

To find out more about our PCB manufacturing capabilities, send us a message now!

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PCB Blog

How to Avoid PCB Tombstoning Defects？

A tombstone defect is a kind of PCB failture. Tombstoning defects occur frequently and are caused by surface mount passive components that are partially lifted from the pads and erected to look like tombstones. But it is not as deadly as a burned component and can be 100% avoided.

What is a tombstone defect in PCB?

Tombstone defects are also called Manhattan effect, Stonehenge effect, or drawbridge effect. It occurs due to torque imbalance caused by different wetting humidity. Wetting is when the solder reaches a fluid state in order to attach the component leads to the pads. Ideally, the solder adheres to both pads while the wetting process is uniform, but unbalanced soldering can result in a standing monument.

Tombstone printed circuit boards are not limited to passive devices; it can also occur on SMT devices.

What are the causes of PCB tombstone defects?

– Unsuitable solder pad design

– Incorrect component placement

– Inconsistent pad size

– Nitrogen

– Uneven reflow oven temperature

– Chip placement parallel to reflow oven

– Inconsistent heating capacity of PCB material

How to avoid tombstone defects in PCBs?

Like other common PCB soldering defects, tombstone defects can be prevented. Please consider the following points.

PCB pad size

Always need to check the pad size is correct, too big or too small can lead to tombstone defects.

PCB surface treatment process

For small size components such as 0201 or 0402, avoid using traditional hot air solder leveling (HASL), which can lead to uneven surfaces.

PCB component placement

In the case of small components encountered, ensure that the alignment widths of the connection pads are equal and they should also be connected in a similar orientation.

Solder resist layer thickness

Ensure that the thickness of the solder resist layer is appropriate to prevent oxidation while not restricting the movement of the solder.

Inner copper overlay

Uneven copper coverage can lead to uneven heating.

Stencil design

A proper stencil design should ensure that there is sufficient solder paste, and in addition, there should be proper component overlap with the paste.

PCB testing

Each component needs to be tested to avoid affecting the function of the PCB. Common PCB tests are

-In-line testing

–Flying probe test

–Automatic optical inspection

-Aging test

-Other functional tests

Trace wiring and power supply layer

The balance of PCB wiring is crucial.

To summarize

PCB soldering defects can lead to PCB failures, resulting in costly recalls and rework. To avoid possible PCB defects, it is important to choose an experienced PCB contract manufacturer. kingPCB provides one-stop PCB manufacturing services with professional wisdom, reliability testing and versatility.

If you have any questions, contact us now or by sales@kingpcb.com and we will respond immediately to any of your requests!

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PCB Blog

Six Reasons for PCB Failures

Just like the age of people, everything has its shelf life. PCB is the lifeblood of the electronic equipment we use, many devices rely on the circuit board, so we must pay attention to the board failure. PCB failure and many reasons, from production in the hands of the final customer use, any one of the links can go wrong. Through this article to understand the common causes of PCB failure, you can easily prevent possible future PCB failure problems.

PCB failure common 6 reasons

  1. PCB defects

Defects are the most common cause of PCB failure, usually generated during the PCB assembly process. Circuit boards are very sensitive to electrostatic discharge (ESD), static electricity generated by thousands of volts can easily damage the PCB components. Other potential defects are unaligned layers, short circuits, cross signals, etc. Reliable PCB manufacturers back to take a variety of preventive measures to eliminate electrostatic discharge on the production floor.

  1. Component problems

Component burn-in is a PCB defect, notably it is the main cause of PCB failure. This requires not only the replacement of parts, there is the possibility of repairing the entire board. Causes of component burn-in include extreme heat, components spaced too close together, the board is not properly connected, etc.

  1. Environment

Circuit boards are also sensitive to external factors. For example, hair, dust, liquids, fibers and other foreign objects in contact with the board can have an adverse effect on the product. In addition, excessive heat and humidity may cause the PCB to expand and thus warp and damage the solder joints.

  1. Solder problems

Solder connects components and circuit boards and is a key component in the PCB process. If the solder is contaminated, or contains too much moisture, it may cause the board to short circuit. There are several common solder defects.

-Open

-Excessive solder

-Component displacement

-Solder bridges

  1. Human error

During the production process, there may be some human errors that lead to PCB failures.

-Misreading the schematic

-Miss installation of components

-Bad soldering

  1. Equipment aging

Every device has its life cycle, after reaching the life cycle may begin to fail, it is a wise move to replace the PCB with a new one, or use a small part of the new one to repair the board.

 How to fix PCB failures?

Ultimately, replacing components and redesigning products is part of the PCB business. Having a partner that understands the details of PCB testing, assembly and remanufacturing can save you time and money.

Choose KingPCB as your PCB supplier, we have a professional team to assist you to better complete your PCB project, contact us now for more information about quotes!