PCB Delamination: Everything You Need To Know in PCBTok

PCB delamination is a problem that has been plaguing the electronics industry for decades. It can cause some serious issues, but it’s not something you have to live with.

If your board gets delaminated, it can mean thousands of dollars in rework and lost productivity time. So what exactly is PCB delamination? And how can you prevent it from happening to your boards?

PCB Delamination

PCB Delamination Explanation

This can happen when there is a misalignment between multiple layers of the PCB substrate due to damage, or when the solder mask layer is damaged.

Delamination occurs when the laminate layer that holds the copper foil and dielectric layers together begins to separate from itself and from the other layers of the PCB.

This can cause problems with connections between components, especially if they are very close together. It can also lead to electric shock if you touch something live while an exposed trace is still connected to a circuit or battery.

What Causes PCB Delamination?

It is caused by the failure of the solder mask, which is the layer that protects the copper traces from corrosion and damage. To understand why this happens, it’s helpful to know a little bit about how PCBs are made.

PCBs are generally made with a double-sided FR-4 substrate material. The substrate has a thin layer of epoxy resin on both sides. A top side layer of copper is applied to one side and then covered with a protective coating that prevents oxidation or corrosion during use.

The protective coating on one side of the board is called a solder mask because its purpose is to prevent solder from bonding to areas of copper where it shouldn’t be soldered. When these areas become exposed due to delamination, they can provide an entry point for water or other contaminants which can cause corrosion and eventually lead to failure over time.

Moisture on PCB

Moisture

This is the main cause of PCB delamination. Delamination occurs when moisture gets between the layers of a PCB, causing them to separate and peel apart. As the moisture evaporates, it can leave behind watermarks in the layers.

The most common cause of PCB delamination is excess humidity. The presence of humidity causes condensation and frosting, which can lead to thermal shock damage on your board. This type of damage can cause delamination over time or immediately after a power surge.

Thermal Stress on PCB

Thermal Stress

PCBs can be prone to thermal stress because they are manufactured using layers of copper and other materials, which are glued together with a heat-curing adhesive.

As the temperature changes, this adhesive can become less effective at holding boards together. The board may still be able to function normally when it is cold, but as it heats up, it will begin to separate.

PCB delamination may also happen when a manufacturer fails to follow proper procedures or use quality materials in their production process.

Poor Manufacturing Process

This can also cause PCB delamination. When a PCB is manufactured, it has to undergo several steps. These steps include etching, plating, and printing. The quality and cleanliness of these processes can affect the material’s integrity and durability.

When your PCB gets delaminated during assembly, it means that there was an issue with one or more of these phases in its manufacturing process. It could be due to lack of proper training or experience on behalf of your manufacturer, or maybe they didn’t use high-quality materials or equipment.

A good manufacturer will always make sure that their employees are properly trained and experienced in all aspects of the manufacturing process before they start working on your order. This way they can ensure that everything goes smoothly without any errors or issues along the way!

Low-Quality Materials

The problem of PCB delamination can be traced back to a few factors, the most prominent being low-quality materials. When the quality of your PCBs is low, there’s a higher likelihood that they’ll break down and begin to separate.

In addition to using lower-quality materials for your PCBs, you can also increase the likelihood of delamination by not utilizing proper techniques for handling them. If you don’t hold onto your PCBs properly when you’re moving them from place to place, or if you drop them on hard surfaces or subject them to extreme temperatures, this can cause damage that leads to delamination.

Incorrect Type of FR-4 Tg Materials

It’s important to use the correct type of FR-4 Tg materials when manufacturing PCBs. FR-4 Tg materials are a type of epoxy that is used in the construction of PCBs. It is important to choose the correct FR-4 Tg material for your final product because it can affect how well your PCBs hold up over time.

If you choose to use an incorrect type of FR-4 Tg material, it can cause your PCBs to delaminate and fall apart prematurely. This can cause problems with their reliability and longevity, which will lead to higher costs for you as a manufacturer.

Delamination vs Measling

Delamination vs Measling Difference

As discussed earlier, delamination is a separation of the layers of your PCB base materials, which creates gaps or bubbles that look like blisters. This occurs in the production process when unwanted heat or humidity are present in your printed circuit board.

Measling is an indication of the disintegration of pieces in the weave inside of the board. Measling can be minor and tolerable as long as it is not frequent or if it does not bridge conductors and soldering eyes. Stress during manufacturing might cause measling.

Types of Tests to Measure Delamination

There are several types of tests that can be used to measure delamination. The most common is scanning acoustic microscopy and thermomechanical analysis. These signs include bubbles, cracks, and other abnormalities in the coating layer.

Scanning Acoustic Microscopy

A non-destructive testing method that uses ultrasound waves to measure the thickness of materials. It’s particularly useful for detecting delamination, which is when two bonded surfaces separate.

This test uses a laser to scan the surface of the material. The laser can create a map of the topography of the sample, which allows researchers to determine whether there are any cracks or other defects. This is one of the most common methods for detecting delamination in composites.

Thermomechanical Analysis

This test measures how much energy is required to break a sample. A thermomechanical analyzer applies pressure to a sample and then measures how much force it takes to break it. If there is no delamination present, then this test should not reveal any changes in breaking force or energy.

It is used to determine the mechanical properties of a material, including its elasticity and strength. It is often used to measure the delamination of materials and can be used to determine the quality of adhesives, coatings, and other products.

Stress Testing Parameters

It is important to have clear, consistent parameters in order to get an accurately printed circuit board to withstand periods of high demand. These are the stress testing parameters to avoid PCB delamination:

Solder Float Test

This is an accelerated lifetime test that simulates the effects of a solder joint subjected to thermal cycling. The solder joint is subjected to six times the number of thermal cycles that it would experience in a normal application. This test is performed at 288°C, which is higher than the typical operating temperature of most electronic components.

N Passes in Reflow Simulation

A common test method is to simulate the high-temperature reflow process by heating up and cooling down the PCB multiple times. In this test, each time the PCB is heated and cooled, it’s called an “N-pass.” The number of passes in which you can see no delamination is your maximum allowable number of N-passes.

Interconnect Stress Test

Without proper testing the common mode is free to roam the entire board, often destroying trace and pad integrity or causing near failure. By performing an Interconnect Stress Test, an engineer can pull out common modes and thereby reduce these problems. This simple test can be performed to save millions of dollars of production costs by identifying prior to manufacture if the printed circuit boards are at risk.

A test that simulates the thermal cycling conditions an assembly will be subjected to during its lifetime. This test is performed by applying a static force to the PCB (6X @ 230℃). The static force is applied for 10 seconds and then released for 30 seconds. This cycle is repeated for one minute. The test duration is kept at one minute to ensure that all material properties are tested under the same conditions.

Time at 260℃ Must be Greater Than 10 Minutes

In order to ensure that your printed circuit board will not delaminate, you must make sure that the time at 260℃ is greater than 10 minutes.

The temperature of the PCB during testing depends on the type of epoxy used in its manufacture. Some epoxies are more heat-resistant than others and require less time at a higher temperature.

How to Prevent PCB Delamination

Preventing PCB delamination depends on knowing exactly what caused it in the first place. If you know what caused your PCB to delaminate, then you can take steps to prevent it from happening again. Here are some tips for preventing PCB delamination:

Keep Dry

PCB delamination is a common problem in circuit boards, which can occur when the board is exposed to moisture or humidity. If you’re storing your circuit board for a long period of time, it’s important to keep it dry.

The best way to do this is by keeping the board in an enclosed container with no holes or cracks that would let in moisture. You can also get a desiccant pack and store it inside the container with your PCB.

Oxide Layer

This is the first line of defense against delamination. It acts as a barrier between the board and the copper traces, preventing them from coming into contact with each other and causing short circuits.

As the board gets damaged and worn over time, this oxide layer can wear away and expose the copper traces. If you notice any exposed copper traces on your PCBs, you’ll need to take steps to prevent these issues from occurring in the future.

Baking of the Board

Baking of board prior to thermal processing is a common practice in the PCB industry. This step is required because moisture can be trapped between the copper and dielectric layers and cause delamination during the thermal process.

Delamination occurs when the copper layer separates from the dielectric and gives rise to an electrical short circuit. Baking of boards prior to thermal processing helps eliminate moisture and other contaminants from the board surface, thereby minimizing the risk of delamination during thermal processing.

Supplier Qualification

Preventing delamination starts with choosing a supplier that can meet your needs and pass all qualification tests. The supplier must be able to provide boards that are acceptable for your process and have passed any additional tests you may need. This article will discuss what you should look for in a supplier. This qualifies the suppliers, and how to test the boards they provide.

Conclusion

The truth is, delamination can happen to anyone. Whether you designed and manufactured your PCBs, or only handled assembly. You’re still responsible for catching potential flaws in the board’s construction. It all starts with proper design techniques and planning, but paying close attention during the production process is equally important. Hopefully, this article has given a better idea of how to spot the signs early on, before they turn into expensive problems later down the line.

PCB Delamination: What You Need To Know

Introduction